THE THOMIST
A SPECULATIVE QUARTERLY REVIEW
OF THEOLOGY AND PHILOSOPHY
EDITORs:

THE DoMINICAN FATHERS oF THE PROVINCE oF ST. JosEPH

Publishers: Sheed & Ward, Inc., New York City
VoL. III

APRIL, 1941

No.2

SOME SUGGESTIONS ON THE RESPECTIVE
SPHERES OF SCIENCE AND PHILOSOPHY
I.

IN WHICH PHILOSOPHY

W

IS DECLARED

INDEPENDENT

oF SciENCE

ITH the rise of modern science a new problem has
arisen for philosophy. How is philosophy to be classified among the other forms of knowledge? To many
of our contemporaries, of course, this is no problem at all;
science is the only form of knowledge; therefore, there is no need
to classify philosophy. Accordingly, what for the philosopher
was originally a somewhat academic question of' classification
has now become a vital question involving the very existence
of philosophy itself. It is this vital question which we wish to
consider in this paper, our-purpose being to show not only that
philosophy is independent of science, but also in what sense it
is independent.
At the outset we might call attention to a distinction between
science and philosophy which has behind it something of the
authority of commonsense usage. The scientist, it is said, strives
for knowledge; the philosopher, for wisdom. Indeed, it is almost
a truism today that while we may know far more than the

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ancients, we are anything but far wiser than they. Our science
has made great strides in the last several centuries. Has our
philosophy progressed likewise?
For all of its plausibility this mere commonsense distinction
between wisdom and knowledge can hardly be regarded as
adequate evidence of the independence of philosophy from
science. After all, what is wisdom? It is surely knowledge of a
kind. Just how is that kind of knowledge which is wisdom to be
differentiated from that kind of knowledge which is science?
Perhaps we can differentiate them by saying that philosophical knowledge is rational, while scientific knowledge is
empirical. With the one are to be associated methods that are
a priori and deductive; 'with the other, methods that are a
posteriori and inductive. But this will not do. Philosophy
simply is not to be identified with Rationalism. This may have
been done in the seventeenth century, but since that time too
much water has gone under the bridge for us ever to try to do it
again. Besides, so far as science is concerned, it is no more exclusively empirical than philosophy is exclusively rational. To
be sure, science is empirical. Yet for all its empiricism, science
is not for that reason non-intellectual and non-rational. Quite
the contrary, the old superstition is now dispelled which says
that the task of the scientist is merely to observe with his senses.
In fact, if there should be found a scientist who still insists that
all he does is to observe, we might quickly silence him by
asking if that means that what he never does is to think. No,
mere sensory observation is inadequate and incomplete, for so
long as sense data are given but not understood, real knowledge has not been attained. Accordingly, it is one of the most
striking features of the history of science that empirical observation is always supplemented by attempts at intellectual explanation. Consider the classic example of Kepler. As a result
of his own and others' empirical observations, he established
the law that the planets move in elliptical orbits. Here was a
fact; it was simply so, and empirical observations proved it.
Yet physicists and astronomers were not content with it as
such. They insisted upon having an explanation of it; they

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wanted to know why planets should behave in this way.
Aristotle's physics could give no accounting of it. As for Kepler
himself he was hardly more successful, his suggestion being
that there was an angel attached to each planet which guided
the planet in its elliptical course. Indeed, it was not until Newton proposed his laws of motion that anything like a real
explanation was forthcoming.
In other words, it would seem that a scientist is not content
with the mere empirical knowledge that a thing is so; he
requires also a rational understanding of why it is so. Perhaps,
in the final analysis it is true that the scientist must be content
with the "how" and cannot hope to attain the "why" of things.
Nevertheless, up to a point and relatively, the scientist does
seek to explain and to understand or, in other words, to know
the "why" of things. Thus it is that hypotheses play the role
that they do in sciences. For it is through hypotheses that what
is empirically observed ·becomes rationally understood-at least
relatively. Einstein's hypothesis was designed to account for
the newly discovered data in the physical world, the evolutionary hypothesis for data of biology and geology, and so on
with all the other hypotheses that are the stock in trade of
every kind and variety of scientist.
Moreover, as regards the notion that the method of science
is purely inductive, that is easily disposed of. For one thing
such a relation as that existing between hypothesis and data is
by no means a merely inductive one. On the contrary, the
significance of the hypothesis lies in the fact that the data can
be regarded as following from it, or as being deducible from it.
Indeed, it is only to the extent that there is deduction from a
hypothesis that there is explanation by a hypothesis. And more
generally, a careful analysis of the factors involved in the
respective processes of induction and deduction certainly indicates that although there may be a real distinction between the
two, there certainly is no separation between them. In fact, it
may be taken as a reliable maxim that there is no deduction
without induction, and no induction without deduction.
With this the conclusion is inescapable: the empiricism of

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HENRY B. VEATCH

science cannot be considered as being a radical empiricism which
excludes all rational reflection and intellectual insight. Nor
must we forget our previous conclusion to the effect that the
rationalism of philosophy is not to be identified with that sort
of seventeenth century . Rationalism which vigorously denies .
any authority to empirical, a posteriori evidence. Unfortunately, if such be our conclusions, we would seem to be more
than ever baffied in our attempt to distinguish between the
kind of knowledge that is philosophical and the kind of knowledge that is scientific. After all, if neither science is exclusively
empirical nor philosophy exclusively rational, there would seem
to be no hope of enforcing upon the two disciplines a requirement of suum cuique. Instead, the methods of both would seem
to be pretty much the same.
Still we must not be overhasty. It may turn out that even
though both science and philosophy are empirical, it is to a
fundamentally different kind of experience that each appeals.
Not only that, but in the light of this possible difference in
method, we may further discover a fundamental difference in
object. At any rate, let us see if anything can be done towards
drawing a distinction between the kind of experience the
scientist appeals to and the kind the philosopher appeals to.
A quotation from Santayana will clarify the issue:
There is one point, indeed, in which I am truly sorry not to be
able to profit by the guidance of my contemporaries. There is now
a great ferment in natural and mathematical philosophy, and the
times seem ripe for a new system of nature, at once ingenious and
comprehensive, such as has not appeared since the earlier days of
Greece. But what exists today is so tentative, obscure and confused
by bad philosophy, that there is no knowing what parts may be
sound and what parts merely personal and scatter-brained. If I
were a mathematician I should no doubt regale myself, if not the
reader with an electric or logistic system of the universe expressed
in algebraic symbols. F'or good or ill, I am an ignorant man, almost
a poet, and I can only spread a feast of what everybody knows.
Fortunately exact science and the books of the learned are not
necessary to establish my essential doctrine, nor can any of them
claim a higher warrant than it has in itself; for it rests on public
experience. It needs, to prove it, only the stars, the
the

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swarm o£ animals, the spectacle o£ birth and death, o£ cities and
wars. My philosophy is justified, and has. been justified in all ages
and countries, by the £acts before every man's eyes; and no great
wit is required to discover it, only (what is rarer than wit) candour
and courage. Learning does not liberate men £rom superstition
when their souls are cowed or perplexed; and, without learning,
clear eyes and honest reflection can discern the hang o£ the world
and distinguish the edge o£ truth £rom the might o£ imagination.
In the past or in the future, my language and my borrowed knowledge would have been different, but under whatever sky I had been
born, since it is the same sky, I should have the same philosophy. 1

This passage from Santayana might well serve as philosophy's
declaration of independence from science. Moreover, of interest
in the quotation are not merely the reasons Santayana does
give for philosophy's right to independence, but also the reasons
he does not give. He does not maintain .that philosophy is
distinguishable from science because it finds its evidence in
pure reason rather than in experience. Quite the contrary, he
maintains that it is precisely in experience that the philosopher
does find his evidence. And yet the experience that the philosopher relies upon is not the same kind of experience that the
scientist relies upon. Instead, it is what Santayana calls a
public experience; it is an experience that has been common to
all men in all times and in all climes; it is the kind of experience
that makes possible the " spreading of a feast of what everybody
knows."
With such an experience contrast the sort of empirical evidence that the scientist bases his conclusions upon. It is not
evidence that all men are familiar with. Nor is it material for
a feast of what everybody knows. Rather it is the private
property of those who can use microscopes and telescopes, who
can handle charts and graphs, and who can find their way
around in laboratories and on field trips. Thus it is that on the
basis of Santayana's remarks we may state that the real
difference between philosophy and science lies in the fact that
1 George Santyana, Skepticism and Animal Faith (New York: 1923), pp. ix-x.
(With the permission of Charles Scribner's Sons.)

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HENRY B. VEATCH

the one uses a so-called common experience, while the other
uses a special experience. 2
No sooner have we laid down this distinction between science
and philosophy, than we have laid ourselves open to an obvious
criticism. We shall be reminded that however much the
distinction between common and special experience may serve
to differentiate philosophy froin science, it serves equally to
degrade philosophy by comparison with science. For common
experience is by definition an experience which is crude and
unrefined. Accordingly, it is argued that because common
experience is crude and unrefined, it is inadequate. Because it
is inadequate, science has long since discarded it in favour of a
source of material which is more inaccessible, to be sure, but
which is richer and more fruitful, none the less. Thus Dr. Franz
Alexander criticizes Professor Adler:
Mr. Adler reduces philosophy to reasoning about inadequate
(common sense) observations, science representing at the same time
reasoning about more adequate observations obtained by refined
and improved methods of investigation . . . . . If Adler's definition of philosophy is correct, philosophy should be discarded in the
proportion to which scientific knowledge progresses by the use of
steadily improving techniques of investigations. 8

Accordingly, if these criticisms of common experience are
sound, then the philosopher, whose distinction is that he relies
upon common experience, must face a most embarrassing
dilemma. Either he is hopelessly behind the times for the reason
that he is working on material that the scientist has long ago
exhausted and discarded; or he is hopelessly ahead of the times
for the reason that he is trying to solve problems which only the
scientist can solvet but which the present state of our data and
material does not yet permit us to solve.
There is however an answer to this criticism of common
experience. The answer is that the criticism contains a non• This distinction between common and special experience is, of course, the one that
Mr. Adler has so vigorously and persuasively argued for.
8 Mortimer J. Adler, What Man Has Made of Man (New York: 1937), preface
by Dr. Franz Alexander, p. xii. (With the permission of Longman's Green & Co.)

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188

sequitur. For how does the argument run? It says that the
trouble with common experience is that,. as experience, there
is not enough of it. It is unrefined, inadequate, and incomplete.
What is needed are more test tubes, microscopes, and precision
instruments. With these it will be possible to gather more
information. With this added information, light will be thrown
upon the various unsolved problems of existence which as yet
have been only toyed with in philosophical speculation, but
which must eventually be solved through scientific investigation.
Such an argument, however, is fallacious; the evidence as
stated is sound, but it is not evidence of the conclusion drawn.
Common experience is, from a certain point of view, experience
that is crude and insufficient; that is true enough. It is also
true that with the acquisition of more delicate instruments of
observation men will be able to gather more information. But
more information about what? Here is just where Dr. Alexander's criticism begs the question. He says that it will be more
information about these fundamental and yet unsolved problems of existence which have so long occupied the attention of
the philosophers. But we say that it will be more information
about no such thing at all. Such added information as the scientist acquires will be added information about the field of science,
but not at all about the field of philosophy. Likewise, the same
answer may be made to the charge that the philosopher bases
his speculations upon an experience that is crude and insufficient. Any philosopher must admit that his common experience
would certainly be crude and insufficient for puposes of science,
but this does not necessarily prove that it is crude and insufficient for purposes of philosophy. Accordingly, any criticisms
of philosophy on this score do little more than beg the question.
Moreover, there is something very interesting about this
defense of common experience as an adequate basis for philosophy. It is interesting because it incidentally brings to light
another ground of distinction between science and philosophy.
Not only do these two differ in method, but now we can perhaps
begin to see how they differ in object also. Thus we spoke of
the field of philosophy and the field of science, and we said that

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HENRY B. VEATCH

what may be very informative about the one, will not necessarily be informative about the other. This is like saying that
what is very important to know when you are building a house,
may well be of very little importance when you are making a
dress. In other words, the world of philosophy is as different
from the world of science as the world of housebuilding from the
world of dressmaking.
More particularly, when we say that the scientist is concerned
about one sort of thing and the philosopher about another sort
of thing, what sort of thing do we mean?
there is in the
history of philosophy the familiar distinction between the world
of phenomena and appearances on the one hand, and the world
of noumena and real existences on the other. Why may we not
appropriate this ancient distinction in order to make clear the
difference in object between science and philosophy? If we
want to know, then, why science requires such a quantity and
variety of data, it is because the field of science is the field of
sensory appearances. Similarly, if we want to know why
philosophy requires nothing like so extensive or so refined an
experience as science, it is because philosophy is not concerned
with the world of phenomena and empirically observable events.
Before we pursue any further this suggestion of a difference
in object between science and philosophy, let us return once
more to a consideration of the difference in method, and let
us trace some of its consequences. The most important consequence is that if common experience really does suffice for
purposes of philosophy, then philosophy is in no wise dependent
upon special experience. If it is not dependent upon special
experience, it is not dependent upon science. That is to say,
the philosopher simply does not have to fuss and fret about
keeping up with the Joneses of science. The reason for this
is that all the advances in science result from new discoveries;
and these new discoveries, by the very fact that they are new,
do not represent an experience that is common to all men in all
ages, but rather an experience that is peculiar to only a few
research workers and special investigators in our own age.
Moreover, there is a corollary to this. If philosophic truth, in

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order to be acquired, need not wait for progress in science, so
also it must be acknowledged that philosophic truth, once it is
acquired, need not fear that it will ever be upset by future
developments in science.
Apparently, then, philosophy must no longer be looked upon
as a mere poor relation hanging on the coattails of science·.
It is a distinct and independent personality with an object and
method of its own.

n. IN WHICH PHILosoPHY Is LIKENED To MATHEMATICs IN
ORDER TO BE CoNTRASTED WITH SciENCE

Such is philosophy's declaration of independence from science.
Unfortunately, in making the declaration, it may be thought
that we have asserted things that are both extreme and contradictory. As an example of our extreme statements may be cited
those assertions to the effect that the philosopher need pay no
heed to the results of science, and that once a philosophic
judgment is established, no possible scientific discovery can ever
upset it. This surely is so extreme as to reduce our position
almost to an absurdity. As an example of our contradictory
a.ssertions may be cited our statement to the effect that philosophy is concerned with the noumenal and intelligible world. Now
this is clearly incompatible with our earlier insistence that
philosophy is not to be identified with Rationalism, and that
the method of philosophy is undeniably empirical.
However, it will not be difficult both to lessen these extremities and to resolve the contradictions. The former we shall
attempt by showing that philosophic judgments are a priori
and, for this reason, immune to either confirmation or refutation
by future experience. The latter we shall attempt by showing
that although the propositions of philosophy are a priori, they
are not for that reason innate; consequently, there is a very
definite sense in which they may be said to be derived from
experience.
In order to accomplish these ends, we shall make a comparison
between philosophy and mathematics. The ground for the

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HENRY B. VEATCH

comparison lies in the fact that in both philosophy and mathematics the judgments are a priori. That is to say, they are
universal and necessary; they represent what must be so and
cannot be otherwise; they are such that their opposites are
inconceivable. For instance, let us consider a few illustrations
of such a priori propositions borrowed from mathematics and
]ogic. Thus we are told that it is inconceivable that a Euclidean
triangle should not have its angles equal to two right angles, or
that a and b should not be greater than a. Similarly, we know
that it is inconceivable that a conclusion should be drawn from
two negative premises, or that an attribute should both be
predicable of a subject and not predicable o£ that subject at one
and the same time and in the same respect. Here we have propositions that are truly
priori, truly universal and necessary.
Now with such propositions, contrast these: "There are
ninety-two elements in the atomic table." " In all living
organisms ontogeny recapitulates phylogeny." Here we have
propositions which perhaps are true, but which differ from those
which preceded in that they do not have the same kind, or at
least not the same degree, of universality and necessity. 0£ the
one sort of proposition the opposite is inconceivable; of the
other sort the opposite is perfectly conceivable, even though
that opposite may in £act be false. Thus there is nothing
inconceivable about there being either more or less than ninetytwo elements. So far as we know, there are in fact just ninetytwo o£ them, but the number, for all we can see, might have
been two or a hundred and two. Similarly, with the biological
principle, there is nothing about the nature of a living organism
as such that would seem to necessitate its having this peculiar
property o£ retracing in its own development the development
of the race. In this regard, the relation o£ a living organism to
its property o£ ontogeny recapitulating phylogeny, and the
relation o£ a Euclidean triangle to its property o£ having its
angles equal to two right angles are as different as day and
night.
Furthermore, we say that future experience is relevant to
such laws o£ chemistry and biology as we have just considered,

a

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but it is in no wise relevant to the mathematical and logical
principles just considered. Thus as regards the ninety-two
elements, there may well come a day when some additional
elements may be discovered, or when some of the ninety-two
already discovered may be reduced to others, thus lessening the
total number. Never will there come a day when some future
experience will reveal that in the realm of quantity a and b is
not greater than a. In other words, so far as the proppsitions
of mathematics and logic are concerned, they need neither hope
for confirmation nor dread of refutation by future experience.
It is in this sense that they are a priori.
Nevertheless, to be a priori does not mean to be innate,
whatever the Platonic, Augustinian, Cartesian tradition may
insist to the contrary. We are not born with any knowledge of
logic, mathematics, or metaphysics. Rather we learn of these
things, as we learn of all things, through experience. The child
comes to know that a straight line is the shortest distance
between two points as a result of many pleasant discoveries,
such as, how much shorter it is to cut across a lawn than to go
around it. As. for a and b being greater than a, it does not take
him long to realize this, considering how early he begins to
persuade his parents that to have both his toys and a piece
of candy is really much better than having just his toys. In
other words, no matter what the purity of our a prioriknowledge
may
it is still from experience that we derive it.
Nevertheless, the derivation is peculiar; it is psychological,
not logical. That is to say, the experience from which an a priori
principle is derived is in no sense evidence of the truth of the
principle; rather it is only a stimulus which provokes an insight
into the truth of the principle. In fact, it is like Newton and
the apple; the apple fell on Newton's head, and lo, the theory
of gravitation resulted. Now, had the apple not fallen, the
theory of gravitation might never have occurred to Newton.
That is hardly to be taken to mean that the falling of an apple
on the great man's head is a necessary step in the demonstration
of the theory of gravitation. Imagine opening the Principa
and reading: " First go out into an orchard and wait until

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HENRY B. VEATCH

an apple falls on your head." Such an axiom would doubtless
make the Newtonian theory
more understandable to
those of us who are mathematically ignorant; but, beyond this,
its advantages would, it seems, be negligible.
Now, what the falling apple was to the theory of graviation,
that experience is to a priori propositions; it is what makes us
think of them; it is not what convinces us of their truth and
validity. Accordingly, it is in this sense that we say that in
mathematics, logic, and philosophy, empirical observation is
psychologically rather than logically relevant. Also it is in this
sense that mathematical, logical, and philosophical knowledge
may be said to be a priori but not iu.nate.
Contrast knowledge in the natural sciences. Like mathematical, logical, and philosophical knowledge, it is not innate;
but unlike them, it is not and can never be a priori. Moreover,
because it can never become a priori knowledge, experience is
essential to it, not accidental; that is to say, empirical observations are logically relevant, not just psychologically relevant,
to the attainment of scientific knowledge. As evidence of this,
consider the examples which we have already given of scientific
judgments. " There are ninety-two elements." " In all living
organisms ontogeny recapitulates phylogeny." Of such propositions the opposites are in no wise inconceivable. There is
nothing in the nature of their subjects which would necessitate
their having such properties. This much has already been
shown. But if the properties and characteristics of things in the
natural world cannot be inferred from a consideration of the
nature of those things themselves, then what can they be
inferred from ? The answer is, " From experience."
Why there should be only ninety-two elements, we do not
know. That there are only ninety-two elements, we learn from
experience. Why in living organisms ontogeny should recapitulate phylogeny, we don't know. That it does so, however,
we are assured by experience. In other words, not being able to
understand the "why" of things in the natural order, experience
would seem to .be the next best thing in that it teaches us the
"how" of things. Since anything like a real understanding or

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insight into the processes o£ nature is denied us, it is experience
that is brought forward and used as a sort of stop-gap against
the floods of total ignorance. Thus, in natural science, experience, instead of being a mere stimulus to an a priori insight
into universal and necessary truths, is rather a substitute for
a knowledge of such truths. Moreover, it is as genuine evidence
and as an essential part of demonstration that experience
functions in the natural sciences; it is logically and not just
psychologically relevant to the attainment of truth.
Are we, then, to infer from this that in the natural sciences
sensation displaces reason ? After all, we have said that
empirical observation serves as a substitute for intellectual
insight. Is there not but one conclusion to be drawn from this?
Scientific evidence is empirical; hence any such thing as rational
evidence can be simply dispensed with in the investigations of
nature.
Such a conclusion, however, would be extreme. Indeed, it
would be in actual conflict with what we have already most
vigorously insisted upon. It was pointed out that just as
philosophy requires experience, so also science requires reason,
and yet this position demanded some qualification. In fact, we
have already qualified it so far as philosophy is concerned;
we have indicated in just what sense philosophy stands in need
of experience. Apparently, then, we must now indicate in just
what sense science stands in need for reason. That it does stand
in need of it is obvious. Consider even the simplest empirical
judgments: "This white thing before me is a sheet of paper " ;
"This green thing in my hand is a fountain pen." Already in
these apparently simple statements of fact the mere sense data
have been transcended. To use the old-fashioned expression,
they have been subsumed under a universal. To use a more
modern expression, they have been put into a certain context,
a context which makes possible their being linked and associated
with other possible data.
For example, if this really is a fountain pen in my hand,
then it will have a point that is sharp to the touch; its holder
will be round and smooth, except where it is threaded for the

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HENRY B. VEATCH

cap; it will have a certain hardness and yet will be hollow
inside. These and any number of other sensible properties will
attach to this object, if it is a fountain pen. In other words,
the purpose of subsuming a datum under a universal or of
putting it into a context is simply to fit it into the natural order
of things. It is just this fitting of a datum into its proper place
in the order of things that cannot be achieved by sensation
alone; it is a task which only the reason can accomplish. In
fact, were it not for the intellect and its power to generalize,
the mere sense data themselves would be meaningless and
insignificant.
This interdependence of reason and experience in science
can be illustrated in another way-in a way we have already
used. It may be remembered that once before when we sought
to show that the empiricism of science was not exclusive of the
use of reason and intellect, we pointed out how scientists are
constantly resorting to hypotheses. Thus it may often appear
to be established empirically that things happen in a certain
way (e. g., that the planets move in elliptical orbits). But this
does not satisfy the man of science. He seeks a hypothesis
that will explain their happening that way (e. g., Newton's
hypotheses in the form of laws of motion). In other words,
there would seem to be in the natural sciences a sort of upward
and downward path, upward from the data to the hypotheses
and downward from the hypotheses to the data again. These
two paths, however, are traced by reason, not by sensation.
Thus once more we find reason supplementing sense in such a
way as to make the mere brute data meaningful and significant.
Indeed, this business of subsuming a particular datum under
a universal concept and this business of explaining an empirical
correlation by means of a hypothesis are not radically distinct.
Instead, they both represent the construction of hypotheses in
order to account for something. Thus even the fitting of a
datum into its context represents the employment of a hypothesis for purposes of explanation, for the context itself is a sort
of hypothesis. Consider the data of greenness and smoothness
and rectangular shape; these do not necessarily and universally

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imply a fountain pen. Nevertheless, to say that theyt are a
fountain pen does explain them and make them intelligible.
Of course, there is always the possibility of error. It !pay be
that the greenness and smoothness and rectangular
are
those of a pencil rather than of a fountain pen. We were
deceived as a result of too hasty a glance, and it is through
further examination that the mistake becomes apparent. Yet,
right here we see the peculiar virtue of hypothesis. Even though
it may be a false one, still it enables us to get hold of our data
and manipulate them so as to set then in relation to other data.
In this way future observations become relevant either as
confirmations or as "infirmations " 4 of what we had supposed
the original data to be. Hypotheses are thus indispensable to a
knowledge of the empirical world; yet hypotheses are the creatures of reason, not of sense.
Now we are ready to summarize our arguments and draw
our conclusions as to the precise nature of the contrast between
science and philosophy. Neither is exclusively rational; neither
is exclusively empirical; and yet for all that, the two do not
follow identical methods of investigation. Thus philosophy
depends upon experience, and yet in a different way from the
way in which science does. So also science stands in need of the
activity of the intellect, and yet in a different way from the way
in which philosophy does. In fact, we might almost say that in
philosophy experience is but a means to the end of intellectual
insight, whereas in science the activity of the intellect serves
merely to set the stage for further empirical observations.
Thus, as we have seen, for the philosopher, as for the mathematician, experience serves only as a stimulus; it is but psychologically, not logically, relevant to an intellectual insight
into a priori truths. On the other hand, for the scientist the
intellect serves but to fashion hypotheses; and of these hypotheses the sole function is to point back to the world of
experience, and thus make possible new experiences. Consequently, whatever may be said of the importance of experience
• For this usage, see Eaton, General Logic, page 545.

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HENRY B. VEATCH

to philosophy and of reason to science, it stili remains true that
the ultimate arbiter and authority for philosophy is the intellect and for science the senses.
These latest conclusions we can now use to reinforce some of
our earlier ones. Consider, for instance, our earlier conclusion
that common experience is adequate for philosophy, whereas
only special experience suffices for science. ·We insisted that
this was so, and we answered objections stating that it was not
so. Yet we never stopped to explain why it was so. Why should
philosophy be able to get along on common experience, while
science requires special experience? The answer to this question
" why " is now clear from what we know of the nature of
scientific knowledge and the nature of philosophical knowledge.
For if observation is but a means to the end of intellectual
insight, then only so much observation is needed as will stimulate such insight. Once this is accomplished, the senses, having
rendered their services, may be paid off and discharged. On the
other hand, where empirical evidence is the end rather than
the means, sensory observation is never finished; it soon goes
beyond the confines of common, everyday experience and
plunges ever deeper and deeper into those perpetually new and
uncharted reaches of experience that are opened up through
refined and special techniques of experiment and investigation.
Moreover, there is another one of our earlier conclusions
which we are now in position to reinforce. It was the conclusion
that not only is the method of philosophy different from that of
science, but also it is towards entirely different kinds of objects
that the two activities are directed. Indeed, without this
difference in object, the difference in method could hardly be
sustained, for suppose we ask why common experience is
sufficient for the philosopher? We have already answered that
question: it is because for the philosopher experience is but a
means to the end of intellectual insight. Suppose we then go on
to ask why for philosophy intellectual insight is the end, whereas
for science the end is empirical observation? The only answer
is that philosophy, like mathematics, is concerned with the
intelligible world, while science deals with the· phenomenal

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world. Were this not so, all of our previous contentions would
become dubious. It would no longer be possible for the philosopher to rely on common experience which is so very crude
compared to the data and materials of the scientist. It would
be actually absurd for the philosopher to pretend to be in no
fear of future empirical discoveries upsetting his conclusions.
However, this latter ceases to be absurd and the former ceases
to be impossible, as soon as it is clearly recognized that the
philosopher is not seeking to know the structure of the sensible
world at all, but only of the intelligible world. That it is the
intelligible world, rather than the sensible world, with which
the philosopher is concerned becomes clear, as soon as the
likeness of philosophy to mathematics and the interest of
philosophy in the a priori are definitely established.

lli.

IN WHICH SOME EMPIRICAL

OBJECTIONS

ARE MET

AND ANSWERED

Philosophy has been classified with mathematics and differentiated from science. As a result, it has been possible to make
clear the different ways in which philosophy and science rely
upon experience, as well as the different worlds with which
these two disciplines are concerned. Yet no sooner have we
established these two points of difference, than we shall be told
that our second point of difference, namely, the differentiation
in object, is peculiarly suspect. For how can we blithely assert
that philosophy is one thing, since it deals with the noumenal
world, while science is another thing, since it deals with the
phenomenal world? After all, suppose we ask ourselves why it
is that so many of our contemporaries flatly refuse to grant
philosophy any sort of respectable status independent of science.
Is it not simply because the ancient myth of an intelligible world
is thought to have been thoroughly deflated and debunked?
What do we mean, then, trying to revive it in this post-Kantian
era of enlightenment?
In short, the issue, as presented to us by our empirically
minded contemporaries, would be simply this: how can we
2

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HENRY B. VEATCH

appeal to the existence of a noumenal world as the source of
philosophy's independence of science, when it was no less than
the denial of the existence of any such world that has been
responsible for the humiliation of philosophy and its reduction
to a state of subjection to science? What we have said about
the a priori character of mathematics, logic, and philosophy is
all very well for mathematics and logic, but it will not do for
philosophy. After all, mathematics and logic are not concerned
with existence or with the real world of nature. They represent
wholly arbitrary constructions of the mind. They are, as the
moderns would say, purely" postulational" or, as Kant would
say, purely analytic. Little wonder, then, that for them experience is only psychologically, and not logically, relevant.
Little wonder that they need not submit themselves either to
confirmation or refutation by experience. With philosophy it is
a different matter. Philosophy does make assertions about
existence, but assertions about existence can only be empirical.
They can neither arise antecedently to experience nor maintain
themselves independently of experience, once they have arisen.
Every item of real knowledge, in fact, is traceable to experience
and subject to revision by experience. Experience, in other
words, is the be-ali and end-all of knowledge-at least, such is
the contention.
Once more we are up against an entrenched empiricism which
simply denies any such thing as an intelligible world and bluntly
challenges reason's right to pronounce upon the nature of things.
Nor will it avail us to remind these empiricists that we are not
defending any such thing as the old-fashioned pure reason,
having explicitly rejected the Rationalist tenet of innate ideas.
No, even that qualified rationalism which we have advocated,
that rationalism which, though it insists that, ultimately,
principles can be reached whose validity is in no wise dependent
on sensation, nevertheless insists with equal vigor that all
knowledge must have its origin and root in the evidence of the
senses-even such rationalism would be rejected by our contemporary crop of empiricists. How, then, are they to be

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answered? How can it be shown that there is such a thing as
an intelligible world?
Unfortunately, we must begin our answering and our demonstrating by admitting that there is one group of empiricists
whom we cannot answer, and for whom we cannot demonstrate-at least not in this paper. That is the group which right
now would seem to be strutting and fretting its hour upon the
philosophical stage. Their favorite lines are replete with words
about meaningful and meaningless concepts, and when they
pronounce them, they strike an air of complete assurance.
They tell us that to talk about any thing that cannot be felt
or touched or in any way sensed is simply to talk nonsense.
Thus if you speak to them of an intelligible world, they blandly
reply that they have no idea what you mean. If you try to
explain, they will cut you short and say that you cannot possibly explain what you mean since you mean nothing. If you
insist that you do mean something and that you can prove that
you do, they will calmly assure you that you are talking
nonsense. If you then appeal to the authority of the great
philosophers and wise men of all ages and urge that these men
use substantially the same concepts and notions as yourself,
they will simply say that that is so much the worse for the
sages and the philosophers; they were talking nonsense too.
"It is no use to argue," they will say," we have set up certain
criteria of meaningfulness; now if anything fails to satisfy these
criteria, even if it makes good sense to us, we will still know
perfectly well that it is nonsense and will refuse to listen."
Obviously, it is no use to argue with these empiricists. They
will not be moved by either rhyme or reason, or, to use their
own jargon, by either emotive meaning or sense meaning.
It is not, then, to this brand of empiricist that we will address
our arguments; rather, it is to that more robust and old-fashioned
breed who might be quite willing to admit that the notion of
an intelligible world is understandable enough, but who would
be equally insistent that, however understandable it is, it
simply does not exist. As for there being such a thing as a real
order of nature, an order that is independent of our knowledge

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HENRY B. VEATCH

of it but that we nevertheless can know, at least partially, this
is all just part and parcel of what our good old-fashioned
empiricist takes for granted. In taking it for granted, he insists
that this same order is an empirical order and can be known
only through sensory experience. He will have none of this
a priori, intelligible world stuff; that is a fiction; when you start
talking about that sort of thing, you have ceased trying to
know and have started to manufacture, and to manufacture
mere cobwebs at that. No, if it is the real you want, the order
of independent, stubborn facts, then stick to your sensory
evidence and don't go wandering off into your a priori land
of nod.
Such is the counsel of our hardheaded, red-blooded man of
experience. Yet, let us look a little more closely at some of
these things that are part and parcel of what he takes for
granted. He says that there is a real order of nature, an order
which we do not create but which we know. What about this
judgment that there is a reality, that something is real? Is
this an empirical judgment in the ordinary sense t
Well, why not call it empirical, if we suppose that it is our
senses that bring us up against real, existing beings? We will
grant that it is they who jolt us out of a mere idle contemplation
of essences and into an honest confrontation of existences.
Very well, then, the content of this judgment which we are
considering certainly belongs to the order of facts and not to
the mere order of logic. For what is this judgment other than
the declaration that there is just such an order of facts; there
is an order of nature; there is reality, being, and existence?
':Ve have here, most assuredly, a judgment about existence,
an empirical judgment, if you like. Consider it for a moment.
Compare it with other characteristically empirical judgments:
" There are ninety-two elements." " There is evolution in
nature." " Ours is an Einsteinian universe." At once, we see
the difference. These latter judgments are in no sense inviolate.
They are subject to revision and rejection, according to what
future experience reveals, but not so the judgment that there
exists something, that there is a real existence. Now can one

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deny or challenge the existence of being ? How can one say
that nothing is? Is not one's very denial of reality based upon
a certain conception of reality? After all, one must ground
one's denial somehow; and what other possible ground can one
give than the very nature of things, the very order of reality
itself ? Any such appeal to the nature of things or to the order
of reality presupP:oses that there are things and that there is a
reality. Put abstractly the point is this: the denial that being
is must be based on a certain notion of what being is, but with
any notion of what being is there is the notion that being is.
In other words, even though it may be possible to doubt
whether reality is this or that, it is altogether impossible to
doubt whether reality is or is not.
What, then, are we to conclude from all this in regard to the
existence of an a priori and of an intelligible world? Well, even
if we admit that the judgment that there is being is not a priori
but empirical, still it must also be admitted by our empiricist
opponent that this same judgment does not have many of the
characteristics which are usually attributed to empirical judgments. There is nothing tentative or hypothetical about it.
On the contrary, it is certain, and its truth is known to be
absolutely immune to any sort of correction from future experience. This, however, would seem to answer precisely to the
description which we previously gave of such modified a priori,
intelligible principles as were to serve as a foundation for
philosophy. At least, then, we would seem to have found a truly
philosophical judgment, founded on common experience and
yet transcendent of experience, in the sense that once it is
established it has no need of submitting itself to further verification in experience.
Before we can gloat too much over having turned the tables
on the good old-fashioned empiricist, we must listen to the
defense prepared in his behalf. For it might be urged that
he of all people would not imagine that experience could ever
disclose the fact that there was no being and no existence.
On the contrary, his honest empiricist's doubts would not
extend to questioning the being of being, but only to questioning

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HENRY B. VEATCH

the essence of being. That being is, is a proposition he would
not challenge, but that being is this rather than that-or to put
it into language more familiar and pleasing to him, that the
order of nature is of this sort rather than that-is a proposition
that cannot be known a prim and antecedently to all experience. Not only that, but even after experience has intervened, there can be no hope that the matter will be settled once
and for all. Rather, the process of appealing to experience must
continue. Thus, once experience has suggested a theory as to
what the order of nature is, that theory must be verified and
possibly modified by further experience. Then these modifications in turn must be verified and still further modified, and
so on ad infinitum.
Such a defense, however, is not sound. For its foundation
it claims the distinction between the fact of existence and the
nature of existence. However, to draw such a distinction by no
means establishes the contention that it is for the philosopher
to discover only the fact of existence, while it is for the scientist
to pronounce upon the nature of existence. On the contrary,
we have already seen for ourselves how the philosophic judgment that there is being leads directly and immediately to other
philosophic judgments about the nature of being. For did we
not show that this very empirical judgment which asserts that
there is existence is different from other empirical judgments,
and that its difference lies primarily in the fact that it can never
be upset by future experience? What is it that makes it thus
inviolate? Must it not be the peculiar nature of its subject
matter? And what is it subject matter? Being. In other
words, no sooner did we discover that there is being and reality,
than we realized that being is of such a nature as to make this
proposition immune to any sort of refutation. A knowledge
of the " that " leads over at once into a knowledge of the
" what," and a knowledge of existence into a knowledge of
essence.
Nor would the empiricist be able to rejoin that for the
philosopher to ascertain only a single item in the essence of
being is not much of an achievement, particularly since all the

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remaining work of determining the nature of things lies within
the competence of the empirical scientist. Quite the contrary,
with the ascertainment of this one item in the nature of being,
any number of other items immediately come into view. What
about this very distinction between existence and essence?
Originally the empiricist himself appealed to it, and
quently we ourselves considered and discussed it. Is this
distinction a scientific one? Is it merely empirical? Hardly,
since, far from being a distinction which is simply a datum of
sense, it is rather a distinction which is presupposed in any
understanding of the data of sense. For how could one possibly
consider or talk about the materials gathered from empirical
observation without considering them under these two aspects
or moments: they are, and they are something? Nor is this
distinction between essence and existence comparable to
scientific judgments insofar as these latter are tentative and
subject to discard. Rather, it is absolutely necessary for us to
conceive of being under these two aspects of existence and
essence. If one supposes that it is not necessary, let him try
to conceive the opposite. By his very act of conception, he
refutes himself.
This sort of polarity of essence and existence is not the only
thing which is implied by the very notion of being itself. There
are also other assertions about the nature of being which the
philosopher can make witb. perfect legitimacy. Admitting that
something exists, can we help admitting at the same time that
whatever exists does exist, and that insofar as it exists and is
something, it does not not exist and is not nothing? Surely
these judgments cannot be denied, for, as Aristotle showed long
ago, in denying them one must presuppose them: each thing
is what it is, and insofar as it is what it is, it is not something
else. Once more we find ourselves in the presence of judgments
which have nothing to anticipate or dread in future experience.
Call them a priori if you like. The fact is that they are not
like scientific judgments; they are not merely tentative; they
do not depend upon the authority of empirical observation;

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HENRY B. VEATCH

in short, the only thing to be said about them is that they are
philosophical judgments.
All this would arouse in our old-fashioned empiricist nothing
but contempt. He would reply: " Once more you drag out the
old battered principles of identity and non-contradiction and
hold them up as exhibits A and B of philosophical knowledge.
Well, let us end the argument once and for all and admit that
these principles do represent philosophical knowledge. Admitting that, what does it prove ? It proves that philosophy is
capable of what everyone has always admitted it to be capable
of-a lot of cobweb spinning. For in virtue of the principles of
identity and non-contradiction, one can construct a whole
system of magnificently interwoven essences, and one can construct it all a priori too. Then when it is done, what does one
have? Nothing but what one started out with-a lot of essences
and no existence. No, if it is the real order of nature that you
want to find, then you won't find it by building a lot of air
castles on top of the principles of identity and non-contradiction.
Instead, you will find it only by the slow and tedious process of
gathering data, propounding hypotheses, and then going back
to the data again for verification. Nor will anything ever be
absolutely certain on the basis of such a method of procedure.
Rather, everything will be merely tentative, and subject to
revision by future experience."
Unfortunately, this reply evades the issue. Originally the
defense proposed for the empiricist was that however much it
might be within the philosopher's province to establish the
being of being, he still could not show a priori what the essence
of being must be. In reply to this, we suggested that it could be
known a priori that the distinction between being and essence
was relevant to the nature of being, and that the principles of
identity and non-contradiction were certainly of the very essence of being. Now we did not say that any more could be
known of the nature and character of being, but we did say
that this much could be. Nor has anything that the empiricist
said served to upset this contention.
Yet, if this is all that the philosopher can know of the essence

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of being, and if everything else about reality falls within the
province of the scientist to discover, then the philosopher's
task is neither a very significant nor a very important one.
However, this is not all that the philosopher can know. Nor
is his further knowledge confined to mere essences, i. e., to a
mere consideration of what might be as over against what
actually is. On the contrary, the philosopher is able to know
that certain essences are, that they exist. He knows, in other
words, not just about natures, but about the nature of things;
or, to put it still differently, he has knowledge not merely of
essence but also of the essence of being, i. e., of the existence
of essences.
To make this assertion carry conviction, let us return once
more to the consideration of those points which we suggested
were simply taken for granted by the ordinary empiricist. It
will be remembered that the admission which we attributed to
him was. that there is a real, natural order of things, an order
which men do not create but rather know. Involved in this
admission is the judgment that there is being, that something
really exists. Already we have shown how this judgment as to
the fact of being is not a scientific judgment at all; and we have
also shown how, close upon the heels of this judgment about
the fact of existence, there follows a whole crowd of judgments
regarding the nature and essence of being, which judgments
are likewise in no way scientific. But the judgment that there
is being is not the only judgment which is involved in the
initial admission of the empiricist. There is also the judgment
that there is knowledge. Besides, if one is going so far as to
adillit that there is a natural order of things, then one must
certainly accede to the judgments that there are things, that
these things are many, and that these many things are subject
to change and becoming.
Once more we have certain judgments of fact comparable
to the judgment that there is being. Suppose we ask what their
basis and origin are. Are they scientific judgments? Are they
a priori? Or just what is their nature? Certainly they cannot
be a priori, since there is nothing about the nature of reality

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HENRY B. VEATCH

considered abstractly, and as such, that would necessitate tJhe
existence of multiplicity, change, and knowledge. Yet there is
no doubt of their certainty. For how can one deny that there is
knowledge? To do so would be but to recommit the age-old
fallacy of the sceptic who professes to have knowledge that
there is no knowledge.
Similarly, would one be any more likely to challenge the
existence of multiplicity and change? Hardly; for, to borrow
Plato's phrase, we may confidently assert that our father,
Parmenides, has long since had violent hands laid upon him,
and to come to his defense now would be to involve oneself in
self-contradiction. For if there is no multiplicity, what of the
opinion that there is? Does this not imply a difference between
truth and illusion? Similarly, if there is no change, what may
be said of the change from an ignorance of this truth to a
knowledge of it ?
Thus once again, we find ourselves in the presence of truths
which, if not purely a priori, at least are not scientific judgments. For there is no tentativeness about them. There is no
chance of their being discredited. Consequently, they are not
like judgments to the effect that there are ninety-two elements
in the atomic table, or that there is a gravitation of bodies.
Not only that, but once these judgments of fact are laid down,
there follow upon them any number of necessary judgments
concerning the nature and essence of the things thus established. Thus no sooner is it established that there is knowledge, than further reflection proceeds to reveal something of
what knowledge is. Knowledge, we learn, necessarily involves
both the distinction and the identification of the knower and
the thing known. How can this be and in just what sense is it
so? These are questions that we learn the answers to only
through still further rational reflection concerning what it is
that knowledge is. Likewise, no sooner is it established that
there is change, than further reflection discloses something of
the nature of change. For example, we come to see how there
must be a something that undergoes the change as well as a
something that instigates and effects the change. In other

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words, any fact of change involves a "from," a "to," an "of,"
and a "by." Does anyone doubt this? How can one? There
is no way of characterizing change without being caught up by
the prepositions "from," "to," "of," and "by"; they are a
part of the very logic of the situation.
You will retort: " All these prepositions are but indicative
of the way we human beings use language and are in no sense
indicative of the way things are." To which the reply is:
" Human beings use language in that way because they think
in that way, and they think in that way because that is the way
things are. If one denies that thinking is thus in conformity
with the order and nature of things, then one is denying that
the order and nature of things can be known. But to profess
to know that there can be no knowledge is self-contradictory,
as we have already seen."
Once more we find ourselves in possession of judgments concerning the nature of things which are certainly not like scientific judgments. They are universal and necessary; they are
certain, not tentative; and they require nothing from future
experience, neither confirmation nor " infirmation." 5 In short,
they are philosophic judgments.
How does it happen that there can be such philosophic
judgments about the nature of knowledge, of essence, of existence, of change, etc.? That there are such judgments we have
just seen. As to how there can be such judgments we perhaps
do not yet see. However, is not the explanation to be found in
the fact that there exists not only a phenomenal world knowable by the scientist, but also an intelligible world knowable by
the philosopher? This is, indeed, an interesting conclusion, for
it was no less than this very question as to whether there is an
intelligible world or not that started us on the course of our
arduous argument. Let us review briefly the issue as it then
presented itself to us. What we had been trying to do for some
time was to differentiate science from philosophy in terms of
method. We had found that in general the methods of the two
• For this usage, see Eaton, General Logic, page 545.

HENRY B. VEATCH

were alike; both made use o£ empirical observation and intellectual investigation. Specifically, however, the methods were
different: in the one case, that of science, rational reflection
was used as a mere means to secure further empirical data; in
the other case, that of philosophy, empirical observation was
but a means to the end of intellectual insight.
Nevertheless, this difference in method between science and
philosophy was not enough; it did not seem to be self-sufficient;
it needed to be grounded upon a difference in object. What
was this difference in object? It was the difference between
the sensible world and the intelligible world, but no sooner
had we reached this point in our discussion than the whole o£
our effort seemed to be rendered useless by the simple consideration that there was no such thing as an intelligible world.
In fact, Kant denied the existence of any such thing, and most
of .our present-day empirically minded scientists would certainly
agree with him. Not only that, but they would go further and
would argue that since there could be no difference between the
object of philosophy and the object o£ science, there could
be no difference in method. If there could be no difference in
method, what possible difference could there be of any kind?
Presumably there could be none. But as soon as it becomes
impossible to differentiate philosophy from science, the fate of
philosophy is sealed, for in our day science is fixed and established. Accordingly, if philosophy cannot prove its independence, it might as well become reconciled to its own nonexistence.
Fortunately, however, philosophy need not become reconciled
to its own non-existence. It does exist and does have a valid
status independent of science. We have just proved it. For did
we not cite examples o£ philosophic judgments, the validity o£
which could not be challenged, and the distinction o£ which
from scientific judgments was apparent? Very well, then, just
as the denial of an intelligible world leads to a denial of philosophy, so also an affirmation o£ philosophy leads to an affirmation
of an intelligible world. For if there are real philosophic judgments that are in no wise scientific judgments, then the method

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of the philosopher must certainly be different from the method
of the scientist. If the method of the philosopher is really
different from that of the scientist, that can only mean that the
philosopher is investigating a different kind of thing from the
scientist, viz., an intelligible world as over against a sensible,
phenomenal world.

IV. IN WHICH PHILOSOPHY

IS LIKENED To SciENCE IN ORDER

TO BE DISTINGUISHED

FROM MATHEMATICS

No sooner have we apparently attained our goal of distinguishing philosophy from science, both as regards method and
as regards object, than we must l).eeds pause a moment to make
sure that we have not overshot our goal. There is something
suspect about this notion of an " intelligible world." Its
associations are all with innate ideas and pure a priori reasoning. This, however, is bad company for us, considering that we
have been at such pains to show how philosophic knowledge
must begin with the data of common experience. In fact, even
such judgments as those involving the law of identity and the
distinction between essence and existence would have no truth
Ol" relevance, unless there were a reality and an existence to
which this law and this distinction could pertain. So also with
the other judgments about the nature of knowledge, of change,
and of multiplicity; unless there were such things as knowledge,
change, and multiplicity, these judgments would have no bearing
or import. How do we know that there are such things? We
know it through common experience. In other words, however
much it may be within the competence of the intellect to
determine what and why things are, it is solely within the
competence of sensory experience to establish the fact that
they are.
Consider this last conclusion. If it is common experience
that assures us of the existence of those very objects which it
is the task of philosophy to reflect upon, what about our earlier
likening of philosophy to mathematics? Is mathematics the
kind of knowledge that must rely upon experience to supply it

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HENRY B. VEATCH

with the actual objects of its investigation? To answer these
questions, let us review our earlier conclusions. It may be
remembered that it was through the supposed similarity of
.philosophy to mathematics that we sought to distinguish
philosophy from science. Science, we suggested, is dependent
upon experience to a greater extent than, and in a different way
from, mathematics and philosophy. In the latter, experience is
only psychologically relevant to the knowledge that is finally
acquired; that is to say, it stimulates such knowledge and
provokes it, but is in no sense a part of it. In natural science,
on the other hand, experience provides the very materials of
scientific investigation; what the scientist knows about, in other
words, are those very objects which are presented to him in
sense experience. Let us take an example. In geometry we may
draw a circle on paper to illustrate some of the theorems which
we are trying to prove. Nevertheless, the geometer will insist
that what we have drawn is not what we are talking or thinking
about. The visible circle, that is to say, merely suggests the
ideal circle and must in no wise be identified with it. Contrast
the procedure in science. There the sense data which are
gathered through experiment are, to be sure, unintelligible
simply in themselves; for an understanding of them much
more is needed than the mere experiencing of them; still, the
understanding which the scientist is seeking is always an understanding of these same data and not of some ideal object merely
suggested by the data.
What of philosophy? Certainly it would seem to be much
more like science than mathematics. Those objects which the
philosopher meets with in common experience are the very same
objects which he considers and tries to determine the nature
of in later reflection. For example, it is through empirical
observation that we come into contact with being and change.
Yet that being which is characterized by the laws of identity
and non-contradiction, and that change which we say necessarily involves the presence of four causes, are not a different
being and a different change from that which we first came to
be aware of in
common experience. On the contrary,

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they are identical. Hence we must accept the conclusion that in
philosophy there is no such separation between the object
experienced and the object known, as there is in mathematics.
Not only that, but we can go further and can assert that,
far from there being in philosophy a separation of the object
known from the object experienced, it is rather through experience, and experience alone, that the philosopher assures
himself of the existence of those very objects whose nature he
is seeking to determine. That there is knowledge, that there is
being, that there is multiplicity, that there is change-these are
all judgments of experience. Of course, when it comes to
knowing what being is and_what knowledge is and what multiplicity is and what change is, the philosopher must learn
about these through intellectual reflection. Nevertheless, it
may be said that philosophy resembles science and differs from
mathematics precisely in its being concerned about existences
and not merely about essences. Thus the philosopher wants
to know, not simply what it is he is considering, but also that
it is. Accordingly, he turns to experience as being the one way
to existence. On the other hand, the mathematician seems
indifferent to existence and so turns away from experience.
For him it is sufficient to know the " what " without the
" that " ; it is sufficient to know merely how his terms are used,
and not whether things corresponding to them really exist or
not. Thus it is that so many modern mathematicians describe
their technique and procedure as being " postulational."
If perchance there should be a mathematician who does not
admit that his method is merely postulational, but who insists
that a mathematical, non-empirical method can and does lead
to existence, then inevitably he will fall into a sort of Cartesian
idealism. It is this sort of idealism of which Professor Gilson
has so brilliantly sketched the history and so tellingly exposed
the fallacy. It consists in trying to make reality conform to
our ideas rather than our ideas to reality. Thus Professor
Gilson says:
The primary consequence of Cartesian mathematicism, and that
from which all the others fiow, was the obligation which he imposed

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HENRY B. vEATCH

upon the philosopher of always going from thought to being and
even of always defining being in terms of thoughts. For the mathematician, the problem of essence always takes precedence over
that of existence; the true circle and the true triangle are the
definition of the circle and of the triangle, the figures empirically
given in sensible experience being only approximations of their
definitions. It is not by chance that geometry is the science of
sciences for Descartes as for Plato. In every respect a systematic
applicatien of the mathematical method to the real could have as
its immediate result nothing but the substitution for the concrete
complexity of things a certain number of clear and distinct ideas,
themselves conceived of as being the veritable reality. 6

Again, he says:
What is a circle, to the mind of a mathematician ? Is it this and
that circle, such as I can imperfectly draw on a piece of paper or on
a blackboard ? Obviously not-the real circle is the definition .of
a circle, and nothing else. It may be that no material figure ever
answered that definition in reality; what the mathematician is
interested in is something different: the essence or true nature of
the circle, as is to be found in its definition and only there. 7

Compare also this expose of the fallacies involved in confusing
the method of philosophy with that of mathematics:
Up to the time of Descartes, and particularly during the Middle
Ages, it had always been admitted that philosophy consists in a
conceptual transposition of reality. In this sense it is just to
characterize it as an abstract conceptualism; but it is not just to
accuse it of having reified its concepts; on the contrary, the constant
method of the scholastic is to go from things to concepts, so that he
needs several concepts to express the essence of a single thing,
according to the multiplicity of the points of view that he adopts
towards it, and also so that no one less than he is in danger of
taking what he abstracts from the real for reality. To convince
oneself of this, it suffices to consider the case of any substance
whatever. For the scholastic, it is always matter and form, that is
to say, two concepts; neither 'is the matter ·anything apart from
the form, nor the form apart from the matter. The person who
reified concepts is not St. Thomas but Descartes, and he could not
avoid doing it as soon as he elevated concepts to the rank of ideas.
• Gilson, Le Realisme Methodique, p. 54.
• Gilson, The Unity of Philosophical Expe:rience, p. 153.

THE RESPECTIVE SPHERES OF SCIENCE AND PHILOSOPHY

209

Abstracts of the real, he made of them models of which it is not
enough to say that the real must conform itself to them but rather
that they are the real itself. The distance which separates the two
philosophers on this point strikes one forcibly when one considers
that for Descartes every substance is known because it is reducible
to the content of his idea, while for a scholastic every substance is
unknown because it is a different thing from the sum of the concepts
which we derive from it. 8

Apparently, then, rather than allow ourselves to be lured
into the pitfalls of Cartesianism we had better shun all mathematical shortcuts to existence, and stick instead to the one and
only way to get from essence to being, namely by experience.
What now of our distinction between philosophy and science?
Is it any longer valid? From what we have just said, it would
appear that so far as its use of experience is concerned, philosophy resembles science and differs from mathematics. Yet from
what we formerly said, it is clear that the real way to demonstrate philosophy's independence of science is to liken it to
mathematics. In fact, all of the cardinal points of contrast
between philosophy and science derive their force and plausibility from the apparent analogy existing between the methods
and objects of investigation in philosophy, and the methods
and objects of investigation in mathematics. For example,
consider the contrast between philosophy and science which is
based on the fact that for the philosopher experience is but a
means to intellectual insight, whereas for the scientist the
intellect is but an instrument in the acquisition of new empirical
data. Obviously, this contrast cannot be even so much as understood, unless one appreciates the close resemblance between
philosophy and mathematics. It is to the mathematician that
one turns, if one wants a stock example of an investigator who
uses experience as but a means, and for whom sense data act
as mere stimuli to knowledge and not at all as materials for
knowledge. Accordingly, if the philosopher is going to insist
that in his case also experience is only psychologically, and not
logically, relevant, he can do so only by admitting the analogy
• Gilson, Le Realisma Methodique, p. 54-55.

3

no

HENRY B. VEATCH

between his method of knowledge and the mathematician's.
Moreover, the same thing is true of that other contrast which
we made between philosophy and science. It was the contrast
based upon the difference between relying upon common experience and relying upon special experience. Yet, surely it
would be to the example of mathematics that a philosopher
would appeal, if he wanted to illustrate how a systematic body
of knowledge could be erected on the foundations of mere
common experience. After all; even a child has enough experience to know the first principles about figure and quantity.
Similarly, in regard to the difference between the phenomenal
and the intelligible worlds, this mode of contrasting philosophy
with science is certainly to be understood after the pattern of
mathematics. That is precisely what the mathematician does;
he passes from the circle that is drawn on paper, the phenomenal,
empirical circle, to the idea of the circle, the intelligible circle.
In short, philosophy can be independent of science only by
identifying its cause with the cause of mathematics. Yet from
what we have said about philosophy's concern with existences,
as over against mere essences, it simply is not possible to make
an identification of philosophy's cause with that of mathematics. Does this mean, then, that philosophy cannot claim independence of science, after all? Hardly, for there is one point
of contrast between science and philosophy which has been
clearly brought to light in our previous discussions, and which,
if we now analyze it more carefully, will definitely settle this
question of independence. What we said was that conclusions
in science are ever subject to revision and refutation, while
conclusions in philosophy are immune to any correction by
future experience. In short, scientific knowledge is only hypothetical, while philosophical knowledge is certain.
Such is the contrast; but how it is to be explained? The
explanation is this: In any sort of experience we first become
aware that certain things are, and immediately thereafter we
want to know what they are-that is, what their nature and
essence are. Now philosophy actually succeeds in penetrating
to the nature and essence of certain things. Thus the philosopher

THE RESPECTIVE SPHERES OF SCIENCE AND PHILOSOPHY

211

not only discovers that being is; but he also discovers something
of the nature of being, for example, that it is subject to the laws
of identity and non-contradiction. Science is not so fortunate.
Thus the physicist discovers that there is physical, atomic being,
but not with absolute certainty. Nor can he know with absolute
certainty what the nature and structure of atomic being is.
To take another example, the philosopher knows that change
is, and he also knows what is essential to all change. The
biologist cannot know with absolute certainty that there is
evolutionary change in all living beings, or even what such
evolutionary change is, supposing that it is.
Here, then, we do have a real distinction between science
and philosophy. Moreover, it is a distinction through which all
of our proposed distinctions between science and philosophy can
be justified and explained. They can be justified and explained
in such a way as to make it no longer necessary to bring in the
analogy of mathematics. Take, for example, the contrast
between science, as being that which uses reason as a means of
attaining further empirical data, and philosophy, as being that
which uses the empirical data as a means to intellectual insight.
The ground for this lies simply in the fact that science never
sees the essence of the given which it investigates; it never
knows what it really is. Consequently, it must resort to hypotheses. What is hypothesis? A hypothesis is simply a kind of
guess as to what the given is, and it is a guess which is made for
want of a knowledge of what the given is. Of course, on the
basis of the evidence at hand and of what we do see of the
given, it may be highly probable that such a hypothesis does
reveal the nature and essence of the given. Yet we cannot be
certain that it does. As long as we cannot be certain about the
essence, we can be almost certain that what we have considered
to be the essence, i. e., our hypothesis, will some day have to be
either altered or destroyed. Thus it is that the scientist must
in all honesty seek out every scrap of evidence that would
either invalidate or substantiate his guess. For that reason,
the scientist's hypotheses are so constructed as to point to
future experience, and it is in this sense that the scientist may

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HENRY B. VEATCH

be said to use reason simply as a means to the attainment of
further empirical data.
On the other hand, the philosopher does succeed in seeing
the very essence of what is given in experience. He sees, in
other words, not merely that something is but also what it is.
This being so, there is no need of further experience. Certain
knowledge has been attained, and certain knowledge, unlike
hypothetical knowledge, is under no obligation to be referent
to future experience. To be sure, in future experience you may
find illustrations and examples of what you know with certainty,
but you will never find proof or disproof thereof. Such is the
sense, then, in which for the philosopher experience is but a
means to intellectual insight.
Similarly, as regards the distinction between a reliance upon
common experience and a reliance upon special experience, it
is clear how its basis is to be found in the distinction between
certain knowledge and hypothetical knowledge. Why is common experience adequate in philosophy ? Because in that which
is given universally and to all men, the philosopher actually
finds those natures and essences which he is looking for. They
are there; he sees them; and in seeing them, he acquires knowledge-knowledge that is certain and beyond refutation. Accordingly, having garnered from common experience enough
material for the attainment of truth, it is unnecessary for the
philosopher to
in more materials which could add nothing
but clutter and confusion. With the scientist, on the other hand,
it is quite different. In common experience he can never find
such a thing as an essence; instead, he finds only accidents. Accordingly, he gathers more data and his experience becomes
more specialized. For all his specialization, he never finds
anything but accidental features. For instance, he can succeed
very well in determining the quantitative aspect of a thing.
Moreover, as his experiments become ever more refined, his
knowledge of the size and shape and speed of the thing in
question becomes ever more accurate. Still, there is always
something lacking. There is lacking that intimate knowledge
of the thing's very nature which alone could make :possible an

THE RESPECTIVE

SPHERES OF SCIENCE AND PHILOSOPHY

213

understanding of just why there should be these particular
quantitative manifestations rather than certain others. Without
this understanding of why things must be the way they are, the
task of the scientist is not yet complete: he does not yet have
knowledge that is certain and beyond refutation. He must
therefore continue his search ever further and further, for,
after all, accidents are infinite in number, and to know all of
them requires a process ad infinitum. Nevertheless, it is just
this process which the scientist must carry on, because, so long
as a certain knowledge of essences is unattainable, an ever more
accurate and extensive knowledge of the accidents is in a sense
an approximation to, in a sense a substitute for, this desired
knowledge of essences.
Apparently, then, it is the certainty of philosophical knowledge in contrast to the tentativeness of scientific knowledge
that provides us with an infallible criterion of the distinction
between philosophy and science. Moreover we have seen how
this distinction maintains itself despite the many similarities
between science and philosophy, and despite the impossibility
of likening philosophy to mathematics in order to distinguish
it from science. Yet, no sooner do we seem to have established
our thesis of the independence of philosophy, than we find that
independence threatened again, this time by the mathematicians
rather than by the scientists. If certainty be the criterion of
philosophy's independence of science, it would appear to be
equally the criterion of philosophy's dependence upon mathematics. What is more characteristic of mathematical knowledge
than certainty? Where could there be found a better example
of certain knowledge than mathematics?
Once more our effort to differentiate philosophy from both
science and mathematics appears to be little more than an effort
to steer between Scylla and Charybdis. If we try to distinguish
philosophy from mathematics, we seem to be forced to liken it
to science; if we try to distinguish it from science, we seem to
be forced to liken it to mathematics. This seeining dilemma,
however, is one that must simply be taken boldly by the horns.
Suppose we adinit that the criterion of distinction between

HENRY B. VEATCH

science and philosophy is the certainty of the philosopher's
conclusions. Suppose we also admit that the distinguishing
feature of mathematics is the certainty of its conclusions. Still,
this does not force us into any embarrasing admission of an
essential similarity between philosophy and mathematics. The
reason is that the certainty achieved in mathematics is not the
same kind of certainty as that achieved in philosophy, for
although the mathematician does achieve certainty, it still is
not a certainty of existence. Rather, it is by means of a retreatfrom existence and reality that mathematics is able to bestow so
high a degree of certitude upon its conclusions. As Professor
Gilson has suggested, it is the ideal which is the standard in
mathematics, not the real. Consequently, the mathematician
pays heed only to the demands of his own definitions and
postulates, and blithely ignores the stubborn exigencies of the
data of sense. The philosopher, on the other hand, heeds only
the exigencies of the given and tries to ignore as completely as
possible whatever pertains merely to his own arbitrary definitions. In other words, the method of philosophy is a method of
description rather than of construction. The true philosopher,
shunning idealism, must never allow himself to confuse the task
of knowing with the task of making. His goal must be one of
submission to an independently real, not one of mastery over
a purely human artifact. To put it in other terms, we may say
that the true end for the philosopher is a knowledge of what
it is that is, and not of what it is that is thought. Similarly,
such certainty as he acquires may be said to be a certainty
about things and not about mere ideas.
Our thesis may now be considered as established: the philosophic quest is distinctive and unique; it is to be confused neither
with scientific nor with mathematical investigations. Nevertheless, since the argument of this section has been devious and
tangled, it might be well for us to summarize it. We began by
pointing out how misleading it was to differentiate philosophy
from science on the ground that philosophy examines an intelJ
Iigible world while science examines a merely phenomenal
world. Far from being a point of distinction, it was-shown how

THE RESPECTIVE

SPHERES OF SCIENCE .AND PHILOSOPHY

215

this is really a point of similarity between philosophy and
science; it is in this precise respect that these two resemble
each other and differ from mathematics. Both are concerned
to know the nature of the very world that is given in experience,
and neither is concerned about the nature of a world, which,
instead of being given in experience, is merely suggested by
experience. After this disclosure of the resemblance of philosophy to science, the question immediately presented itself as to
the independence of philosophy from science. Could this any
longer be maintained? That it could be, we tried to show by
pointing to the certainty of philosophical conclusions in contrast to the merely hypothetical character of results in science.
At the same time we were careful to distinguish the kind of
certainty found in philosophy from the kind of certainty there
is in mathematics: the latter is not a certainty about existence;
the former is.

V. SUMMARY .AND CoNCLUSION
Having thus summarized our final section, it might be well
for us to summarize our whole paper. In the first section,
we stated the case for philosophy's independence of science.
In philosophical inquiries a different method is used from that
in science; reliance is placed on common rather than on special
experience. Also in philosophical inquiries a different object
is investigated, namely the intelligible world, in contrast to
the phenomenal world. In the second section, we undertook to
explain and justify what we had been content simply to present
and affirm in the first section, namely philosophy's independence
of science. This was done by comparing philosophy to mathematics. By this means it was possible to show that philosophical
judgments were a priori, and hence independent of any conclusions that either had been or might be established as a result
of the special experience of the scientist. At the same time,
it was explained how, even though philosophic judgments were
a priori, they were not innate. As a result, the method of
philosophy was said to be an empirical method, having its
origin in common experience-and this, despite the fact that

216

HENRY B. VEATCH

the object of philosophy was the intelligible world. Having
reached this point, we were forced in the third section to consider certain empiricist objections which challenged the possibility of any a prioriknowledge of reality, as well as the existence
of any such thing as a;n intelligible world. In answer to these
attacks we simply presented various philosophical judgments,
which were clearly judgments about reality, and which at the
same time were clearly a priori in the sense of being neither
based on past scientific discoveries nor subject to correction by
future ones. In other words, it is simply a fact that there are
philosophical judgments, and that these judgments are not of
the character of scientific judgments. However, with this as
the conclusion of the third section, the questions still remained
open as to whether the object of philosophy was not after all
the intelligible world, and as to whether the method of philosophy was not essentially mathematical. In the fourth section
both these questions were answered in the negative. Philosophy
investigates the world of the empirically
just as does
science. Nor is the method of philosophy mathematical, the
aim of philosophy being not so much to construct as to describe.
Throughout the whole discussion our thesis has been that
philosophy represents a different kind of knowledge from that
of science. In the course of the paper we hope we have shown
in what sense the one kind of knowledge is different from the
other. There is still another question as to why there should
be these different knowledges. 10 That they are different, and
how they are different, we have seen. Why they are different is
a question that must wait for another time.
HENRY

B. VEATCH

Department of Philosophy,
Indiana University,
Bloomington, Indiana

9 This conclusion would doubtless have to be qualified in order to take account
of the rather special case of natural theology.
conversation Professor Gilson once remarked on how this now
1.o In a private
arcltaic usage was once in respectable currency, notably in Bacon.

THE DISTINCTIVE NATURE OF THE GIFT
OF UNDERSTANDING
A Commentary on the "Summa Theologica," II-II, Q. 8

T

I. THE GIFTS IN' GENERAL

HERE is nothing in the purely physical order of things
that affords a parallel to the action of the Holy Ghost
on the supernatural life of man. Although at first sight
symbiosis seems to be an apt concept to illustrate the relations
of this sweet and mysterious Guest to His living temple, closer
examination reveals so many awkward and misleading details
that the example becomes nearly worthless. The algae in a
lichen, or the intestinal protozoa in termites, contribute to their
partner's nourishment in a state which makes it easier to
assimilate, receiving in return food elements which unaided they
could not obtain, and the craven crab in return for the seaanemone's protection carries it to pastures ever new. But in all
this the most noticable point is the mutual aspect of the
partnership; the quid JYTO quo is strongly emphasized. The
indwelling of the Holy Ghost on the other hand is unilateral.
It would be closer to say, with certain reservations, that man
dwells in- the Holy Ghost, for while he contributes nothing to
the self-sufficient Divinity, he receives much, and receives it
all as a pure gift. Whence the Church on Pentecost sings of
the Holy Spirit as " Gift of the most high God."
The dependence of man on the Holy Ghost is manifold. His
every act as well as his very being depend on Him, " For in
Him we live and move and are." 1 He moves us to the particular good that we do, both in the physical and moral order,
and that too, sometimes, in an extraordinary manner, as when
the spirit of God " rushed " upon Balaam. 2 A fortiori, then,
1

Acts, xvii,

• Numbers, xxiv,

Yl17

218

JOSEPH IGNATIUS

MCGUINESS

He moves us in the supernatural order: " Likewise the Spirit
helpeth also our infirmity." 3 But in this order there are two
modes of action, human and divine. Under the influence of the
Holy Ghost the infused virtues elicit their proper operations.
These actions are from an intrinsic principle, are regulated
by reason, whence comes the human mode, and in a sense are
in our possession, for if, on the one hand, supernatural aid is
required, on the other, man himself must determine for himself
just what and how much he will do, so that in the words of
St. Paul, " Every man shall receive his own reward, according
to his own labor." 4 But, over, and above this, there is another
sort of motion in which man is more acted upon than acting
and is moved, in a manner entirely beyond his powers, to his
supernatural end: " But when they shall deliver you up, take
no thought as to what or how to speak ... for it is not you who
speak, but the spirit o£ your Father who speaketh in you." 5
Jesus was led into the desert; 6 the minds of the disciples
were opened. 7 These motions do not proceed from man according to the intrinsic principle of reason, after the human
mode, but from an extrinsic principle, the Holy Ghost, after
a manner that is superhuman and divine. They do not
proceed from any deliberation on our part, although they are
free, resulting from a particular impulse of the Holy Ghost
activating special supernatural habits to which, nowadays,
the.· word "gifts,; is reserved. 8
St. Thomas points out in the first article of question sixtyeight, where he is distinguishing the gifts from the virtues,
that we ought to follow the manner of speaking of Holy
Scripture which calls the gifts " spiritus," or breaths, " because they are in us by divine inspiration." ·a Father Gardeil
8 Romans, viii, 26.
'I Cor., iii, 8.
• Matthew, x. 19-20.
8 Matthew, iv, I; Mark, i, 12; Luke, iv, I.
• Luke, xxiv, 25.
8 G. M. Paris, 0. P., Dissertatio de Donis Spiritus Sancti in Genere (Turin:

Marietti, 1930), p. 10.

• Summa Theol.,

q. 68, a. I.

THE NATURE OF THE GIFT OF UNDERSTANDING

219

remarks the richly-laden signification of St. Thomas' words.
That " because "-secundum quod--in the mouth of a scholastic is the affirmation of an essence or the essential and
immediate property of an essence, and not mere consequence.10 Inspiration signifies some sort of motion from without. Hence the essential note of the gifts of the Holy Ghost
is that He is the mover, and not reason as in the virtues.
Holy Scripture also speaks of the Spirit resting within us,
for as St. John Chrysostom says: "Mter He comes, He remains, nor does He depart." Just as the moral virtues perfect
the appetitive faculties by rendering them obedient to the
commands of reason, so there are dispositions in the faculties
of the soul rendering them obedient to the motions of the Holy
Ghost. For to the degree that the moving principle is exalted,
by that much more is it fitting that the subject be disposed
to receive this motion so that there be a proportion between
the mover and the one moved. And so, where the mover is
most powerful, by His very motion almost He induces a
habit in the subject if He moves him as one dwelling within
him. 11 Of course, actual grace in sinners causes no habit to
be formed, but this is where a sinner and a person in the
state of grace differ. The just man has in himself habitual
principles needing the motion of grace, which principles also
habilitate him in the order of a well-disposed subject to every
impulse of the First Mover and the Leader of minds to eternal
life.12 So, as St. Thomas notes, because man is endowed with
free will, he himself acts even under the action of the Holy
Spirit, and requires a habit, a permanent disposition rendering
him prompt to follow the motion of the Holy Spirit. 18 This is
the narrowest and proper sense of " gift."
In the thought of St. Thomas, the seven gifts enumerated
by Isaias are distinguished among themselves according to
the powers of man which they perfect. Four gifts are seated in
Dictionnaire de Theologie Catkolique, Vol. 4, part
col. 1775.
Paris, op. cit., p. 51.
12 L. Billot, De Virtutibus Infusis
(Rome: 1905), I, 183.
18 Summa Tkeol., I-II, q. 68, a.
ad 2um.
10

11

JOSEPH IGNATIUS

MCGUINESS

reason: wisdom, understanding, knowledge, and counsel; and
the remaining three in the will: fortitude, piety, and fear of the
Lord. To further distinguish the intellectual gifts, St. Thomas
encountered some difficulty. In his first attempt, he uses as his
norms the distinction of the speculative and practica] reason,
and the difference between the two acts of the intellect, apprehension and judgment. Within this frame, he places understanding in the speculative apprehension, wisdom in the speculative judgment, knowledge in the practical fudgment and counsel
in the practical apprehension of truth. 14 Further thought led
him to modify, not the distinction of the gifts, btit the basis
for it, so that when he comes to the distinction of the gifts in
particular, we find he has enlarged the office of the gifts without
confusing the particular operation of each. "He wishes understanding to be penetrative of all, wisdom the judge of all
through the very highest cause, knowledge likewise the judge
through created or proper causes, and counsel likewise applicative of all to work; and follow this," says Cajetan, " because it is
of a more divine ingenuity." 15
Ingenious though it may be to Cajetan, it does not at first
glance offer a clear statement of the distinct office of each of the
various gifts. Only by a careful scrutiny of St. Thomas will
some light be shed on the difficulties. This paper proposes to
establish the distinctive nature of the gift of understanding
according to the mind of St. Thomas.

II. THE GIFT OF UNDERSTANDING
In treating of the gift of understanding, there are some
difficulties to be borne in Inind and, if possible, answered as we
go along. The first and foremost is that the operation of this
gift is found most perfectly in the mystical states and cannot be
well expressed in human language. As St. John of the Cross
says, "Keep in Inind that these matters are beyond all words.
The intelligence of pure truths requires for its proper explanation that God should hold the hand and wield the pen of the
u Ibid., q. 64, a. 4;

15

Comm. in I-II, q. 68, a. 4.

THE NATURE OF THE GIFT OF UNDERSTANDING

!il!ill

writer." 16 The same excess of light that caused St. Thomas to
leave the Summa unfinished leaves the operation of this gift
indescribable, except in halting and inept terms.
Further, it is necessary to distinguish understanding from
faith, a difficult task because it seems that an act of faith can
fill the office of the gift. To distinguish understanding from
other intellectual gifts, moreover, is difficult because it cannot
readily be shown just what act understanding exercises that the
others cannot exercise. And, finally, because it is not bound to
the state of the wayfarer, or of faith, we must explain what act
it exercises in heaven when it is found without faith, to the
aid of which, however, it was ordained in this life.17
The precise and detailed treatment of the gift of understanding is found in the eight articles of the eighth question of the
Secunda Secundae of the Summa Theologica. In the first
article, St. Thomas gives a purely nominal definition of what he
means by the gift of understanding, sketches the similarities
and differences between the natural and supernatural gift,
and indicates broadly the objects to which the gift will extend.
In developing these general notions, St. Thomas proceeds in the
orderly fashion so characteristic of him. " Since the gifts are
ordained to operation, it is fitting that they be distinguished
according to their object, in which acts are diversified according
to their species." 18 So in his following articles the principles
. enunciated in Part One of the Summa Theologica 19 are applied.
There are three ways to distinguish habits: by the active
principles which give rise to them, by the natures to which
they are ordained and in which they inhere, and by the operation to which they are ordained, that is, their formal object.
In the first and third ways, the gifts in general have been
distinguished from the virtues, and in the second way the
intellectual gifts from those in the appetitive faculties. Now
10
11

Ascent of Mt. Carmel, Bk. II, c. fl6.
Cf. John of St. Thomas, CurSUB Theologicus, I-II, disp. XVIII, a. 8 (Lyons:

1668).
18
10

III Sent., d. XXXIV, q. 1, a. 6.
Summa Theol., I, q. 18, a. 2; q. 54, a. 2.

JOSEPH IGNATIUS

MCGUINESS

it remains to employ the second and third ways to distinguish
understanding from the three others: wisdom, knowledge, and
counsel.
Because of the external order of the questions, the first thing
to notice is that understanding is linked in some way with the
theological virtue of faith. This relation is the subject of the
second article. Here is determined the relations of understanding and faith by delimiting their objects and therefore
their sphere of action. Here also are described the proper and
extended objects of the gift; so, in the third article the object
by extension is discussed and also the faculty in which understanding is found._
Speaking of the faculty in which it is found, St. Thomas,
in articles four and five, lays the psychological basis in the
supernatural order which demands the gift. In the fourth, we
find that charity is the raison d' etre of this gift, and in the
fifth the utter dependence of the gift on grace is emphasized
by a special discussion of unformed faith. Despite the fact that
the virtue of faith, which is the rule and reason of the gift,
remains in a truncated fashion without charity, yet understanding cannot remain to aid it.
Now that the nature of the gift is fairly well established
from its subject and object, it should be an easy matter, in
article six, to distinguish it from the other gifts. And, :finally,
according to his general plan in his special treatment of each
gift, St. Thomas, in the seventh article, tops off his consideration
of this gift with its corresponding beatitude and, in the eighth,
considers the corresponding fruits of the Holy Ghost. The
logical order of the whole discussion is evident and commends
itself to us as the guide to follow as we progress.
The gifts are all connected in charity and the Holy Ghost, 2{)
just as all the virtues are connected in prudence and reason.
This is perhaps the reason why St. Thomas finds it so hard to
keep the notions proper to wisdom and knowledge out of his
discussion of understanding. ·Terms like " regulate " and
Summa Theol., I-ll, q. 68, a. 5.

THE NATURE OF THE GIFT OF UNDERSTANDING

estimation " seem to savor of the gift of wisdom rather than
understanding, and we shall try to explain them when we come
to them.
For the existence of the gift of understanding, St. Thomas
is content to accept the authority of Holy Scripture. Although
the text which he cites in the Sed Contra of the first article
could cause some difficulty were it the sole foundation of the
doctrine of the gifts, there are many other places in Sacred
Scripture where the working of the Holy Ghost is indicated.
Joseph is described as a " man full of the Spirit of God,"
because he interpreted the dream of Pharaoh. 21 Those who
made the priestly vestments of Aaron were filled with the
" spirit of wisdom," 22 and Beseleel was filled " with the spirit
of God, with wisdom and understanding, and knowledge in all
manner of work." 23 The " spirit " that inspired Moses was
taken from him and given to seventy men, 24 and " when the
spirit had rested upon them they prophesied, nor did they
cease afterwards." 25 Many of the great figures of the Old
Testament are noted as being blessed with a special spirit:
" ... and Josue was filled with the spirit of wisdom ... "; 211
" ... and the spirit of the Lord was in him, (Othoniel) and he
judged Israel."; 127 ". • • the spirit of the Lord came upon
Gedeon ... "; 28 "the spirit of the Lord came upon Jepthe ... "; 29
". . . the spirit of the Lord began to be with him (Samson) ... "; 30 " ••• the spirit of the Lord came upon David
from that day forward . . . but the spirit of the Lord departed
from Saul." 31 The sapiential works and the Psalms are filled
with references to the gifts of wisdom and understanding: " I
will bless the Lord who hath given me understanding."; 32
"Give me understanding and I will search thy law .... "; 33
Genesis, xli, 38.
•• ExodUII, xxviii, 3.
•• Ibid., xxxi, 3.
•• Numbers, xi, 17.
21

•• Ibid.,
Deuteronomy, xxxiv, 9.
27 Judges, iii, 10.

28

·•• Ibid., vi, 34.
•• Ibid., xi,
•• Ibid., xiii,
31 I Kings, xvi, 3.
•• Ps., xv, 7.
•• Ibid., cxviii, 34.

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"By thy commandments I have had understanding.
The classic text is from Isaias:

"

84

And the spirit of the Lord shall rest upon him; the spirit of
wisdom and of understanding, the spirit of counsel and of fortitude,
the spirit of knowledge and of godliness. And he shall be filled with
the spirit of the fear of the Lord. He shall not judge according to
the sight of the eyes, nor reprove according to the hearing of the
ears.35
Isaias pictures a perfect judge who, thanks to the special
dignity and power that the spirit of the Lord will confer upon
him, will give special attention to those so often neglected in the
Orient. The effects that the permanent dwelling of the spirit
produces are the qualities of an ideal judge: wisdom to know
the true point of view; understanding, the gift of discernment,
of judgment, to comprehend the circumstances and the other
facts that can influence or determine the sentence; counsel,
the art of choosing the means most proper in a given case;
fortitude, making him superior to obstacles and respect of
persons; knowledge of the law; and in all his actions respect
for God, piety and fear of the Lord. 86
In most of these citations it is not clear either from the
text or the context that the gifts of the Holy Ghost in their
narrowest and strictest meaning are meant, but the whole
series shows the operation of the spirit of God, the Holy Spirit,
in a particular way. Isaias crystalizes the vague expressions of
his precursors into a powerful and moving picture of the messianic Judge, and this picture under the skillful interpretation
of the Fathers and Doctors, from Justin to Gregory, becomes
the basis for the doctrine of the gifts in St. Thomas and the
Church. As Pere Touzard remarks at the close of his article,
" From the last Father of the Church to the Angel of the
Schools is not far." 37 With this wealth of tradition as well as
•• Ibid .• 104.

Is., xi, 2-8.
J. Touzard, "Isaie, XI, 2-3a et Les Sept Dons du Saint Esprit," Revue
Biblique, VIII (1899), 250.
•• Ibid., p. 266.
35

38

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225

Scripture behind him, St. Thomas assumes the existence of
the gift. His first concern is not to establish its existence, but
to clarify the confusion involved in the term " intellectus "
The term is taken from intus and legere, to read within, the
intimate penetration of truth. 88
The word intellectus has many meanings in Scholastic
language. It sometimes means the essence of the soul itself,
because the soul may be denominated by its principal power.
In the III de Anima and in many places of the Summa, those
wonderful creatures we call angels are called I ntellectus or
lntelligentiae. Again the word sometimes means that potency
of the soul which enables it to know, as distinct from the will.
This intellective potency is further divided into the intellectus
agens and the intellectus possibilis. Very often it means a
natural habit, one of the intellectual virtues, the habit of first
principles. It may also designate one of the integral parts of
prudence, a knowledge of present matters and a just estimate
of some particular end in the light of ultimate principles which
are accepted asperse known. And, finally, it signifies, as a gift
of the Holy Ghost, a certain acute penetration of divine things.
Here, 89 it means neither an intellective potency, nor a habit
of first principles, but a habit divinely infused by which one so
penetrates the mysteries of the Christian religion that he sees
that the arguments which are opposed to them do not lessen
their truth, whether he can solve the arguments or not. 4n St.
Thomas gives various descriptions of what he means by the
gift of understanding: it is" a supernatural light," 41 a" certain
excellence of knowledge penetrating to the very core"; 42 it
"implies a certain penetration of truth"; 43 its function is "to
penetrate what is said." 44
A nominal definition joined to what he has taught on the
gifts in general would be enough to answer the question St.
Thomas poses in the first article, i. e., "Is understanding a gift
38 Summa Theol., IT-II, q. 8, a. I; q. 49, a. 5, ad Sum.
•• Ibid., II-II, q. 8, a. I.
•• Ibid., ad Sum.
•o Sylvius, Oomm. in II-II, q. 8.
•• Ibid., a. 5, ad Sum.
•• Ibid., a. 6, ad 2um.
" Summa Theol .• II-II, q. 8, a. I.

4

JOSEPH IGNATIUS

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of the Holy Ghost ? " 45 He goes further, however, and shows
something of the nature of the gift, its subject, and the objects
to which it extends; in the answer to the first objection he
expressly declares what he only implied in the body of the
article, that the gift is necessary for salvation.
By calling this gift a light, and comparing it with the natural
light which is better known to us, he not only gives us a glimpse
of its nature, but harmoniously blends the working of the
supernatural in us with the natural. The background against
which all this discussion must move is the fundamental principle
that man is ordered to a supernatural
Since man's
knowledge begins from the sense and from something external,
it is evident that his knowledge will penetrate to essences only
to the degree of power that the light of his intellect enjoys.
But the strength of this light is limited, and the depth of his
penetration is determined by nature. To ferret out those things
which though necessary because of his end, exceed his natural
powers, man needs assistance from the same order as his end.
This is the gift of understanding which is a supernatural light.
For St. Thomas, man may enjoy three different lights, not
always simultaneously, but varying with different individuals
in different states. The highest of these is called the light of
glory. This is found only in the just who are enjoying the
beatific vision. It is a supernatural habitual quality, an augmentation of the intellective power " after the manner in
which a potency is made more powerful to act through a habit
inhering in it." 47 To see God face to face is far above the
powers of any created faculty left to its own resources, and so
God strengthens it by infusing this new light into the soul,
not as a medium in which God is seen, but as an added perfection strenghtening the intellect to see God immediately.
This light of glory is the culmination of another light which
man can enjoy while on earth. Thomas calls it the light of grace. 48
It too is supernatural in origin, and a quality perfecting the soul
•• Ibid., a. 1.
•• Ibid., I-ll, q. 3, a. 8.

"Ibid., I, q. 12, a. 5, ad lum.
•• Ibid., I-ll, q. 109, a. 1.

THE NATURE OF THE GIFT OF UNDERSTANDING

227

to know, in this life, things that are beyond the limits of its
natural powers. There are at least two common forms that it
takes-the light of faith and the light of prophecy. The latter
is not a habitual perfection, but rather a vivid and fleeting
glimpse of things to be revealed which comes and goes as God
wills, in order that the things seen in its transient light may be
passed on to mankind by the prophet. Nor does it presuppose
charity in the soul. The light of faith is the result of a habit,
the virtue of faith joining us to God, and lasts as long as faith
remains. Not only does it extend the field of our knowledge by
putting us in contact with truths which we could not otherwise
know or assent to, but it contributes a new insight into the
things with which the natural power of the intellect is engaged.
This natural power of the intellect is also called a light,
the natural light of man, or the natural light of the active
intellect. We speak of intellectual light after the manner of
corporeal light. Now corporeal light is the medium by which
we see, and it serves vision in a twofold manner. On one hand,
through it a thing only potentially visible becomes actually so,
as while driving on a dark night, only that portion of the
potentially visible countryside which the headlights illumine
is actually seen. On the other, the power of sight itself is
strengthened to see. By analogy then, intellectual light can be
either the power of the intellect to understand, or also that by
which something becomes known to us. 49
The light of the gift of understanding should have a place
in this outline. It is not the light of glory despite the great
similarities between the two. The light of glory once attained
is inamissable, but since the gifts are founded in charity which
is lost by mortal sin:, they too can be lost. We know from faith
that while on earth, Christ enjoyed the beatific vision, and at
the same time all the gifts. A posteriori then, they are distinct.
And, finally, we have the famous dictum of St. Gregory, "No
one, as long as he lives in mortal flesh, so advances in the
strength of his contemplation, that the eye of his mind fixes
•• Q. D. de Ver., q. 9, a. I.

JOSEPH

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upon a ray of the uncircumscribed light; whatever is seen in
this manner is not God Himself, but under Him." 50 We shall
return to this question _later.
Since the light of understanding is a supernatural light, it
cannot be the light of reason, which leaves only the light of
grace. As a matter of fact, a sober and objective examination
of the first article will reveal that this is as far as St. Thomas
cares to proceed. His argument concludes no further than the
necessity for a supernatural light and is practically the same
as the argument advanced for the existence of a light of grace:
... and those things to which we cannot conclude from first principles exceed the natural light of the intellect. Of this sort are
matters of faith, future contingents, and the like, and therefore
a knowledge of these truths cannot be had without a light of grace
freely given, such as the light of faith or of prophecy or something
of the sort. 51
And in the Summa, in answer to the question of whether a
knowledge of truth is possible without grace, he says:
. . . the human understanding has a form, namely, intelligible
light, which of itself is sufficient for knowing certain intelligible
things, those, namely, which we can come to know through the
senses. Higher intelligible things the human intellect cannot know
unless it be perfected by a stronger light, the light of faith or
prophecy, which is called the light of grace inasmuch as it is added
to nature. 52
Here in answer to the question whether understanding is a gift
of the Holy Ghost, he replies:
. . . the natural light of our understanding is of finite power;
wherefore it can reach to a certain fixed point. Consequently man
needs a supernatural light in order to penetrate further still so as
to know what he cannot know by natural light; and this supernatural light given to man is called the gift of intellect ... 53
This is his general concept which St. Thomas, as he proceeds in
50 Homiliae XL in Ezeehielem, Lib. II, Hom. II, P. L. Vol. 76, col. 956.
"'II Sent., d. XXVIII, q. 1, a. 5.
•• Summa Theol., I-II, q. 109, a. 1, c.
•• Ibid., II-II, q. 8, a. 1.

THE NATURE OF THE GIFT OF UNDERSTANDING

229

his tract, trims, bends and polishes until the precise nature of
the gift is apparent.
There are three orders of being with unequal powers who
can illumine the human mind. Man can enlighten another man
in two ways. He can propose some object for consideration
and so lead another to a knowledge of it, as when a guide points
out some monument or inscription. But, as St. Thomas and
Cajetan observe, this is not, properly speaking, illumination,
but only locution. 54 For real illumination it is not sufficient
to merely offer a truth; it must be offered as illumined by the
mind of the one who presents it, as when a teacher illumines
the mind of a student. This familiar process is thus described
by Baiiez,
There are two things required for the knowledge of truth,apprehension and judgment. Some truth can be hidden from the
intellect either because the intellect is not strong enough to apprehend it since it is not proposed proportionately, or because it
cannot make a certain judgment about it on account of the
deficiency of light which is the proper principle of judgment.
Whence it follows that the manifestation of truth can be twofold,
either on the ;part of the apprehension, as when the master teaches
the student to form a proper concept of some conclusion, using
similar examples, distinctions, etc.; or on the part of the judgment,
as when the master proposes to the pupil principles and means
guided by which he can judge of the conclusion. 55
Referring to several pertinent passages from St. Thomas, 56
Baiiez continues:
The intelligible principle to which the conclusion is resolved has the
notion of intellectual light under which the intellect judges of the
truth of the conclusion, 56 •
Mention here of a passage from Cajetan will throw further
light on the matter:
There is in the teacher an active ordination of his proper concept
•• II Sent., d. IX, q. 1, a. and 4um; cf. Cajetan, Comm. in I, q. 106, a. 1.
•• Banez, Comm. in I, q. 106, a. 1.
•• Summa Theol., II-II, q. 15, a. 1; Q. D. de Ver., q. 9, a. 1, ad
••• Banez, loc. cit.

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illustrating and measuring to the student the thing conceived.
The student applies his intellect to the formation of a concept
corresponding to the concept of the same thing he has been shown,
and so he participates in the superior light of the professor.
Thus there comes to be, in some fashion, in the student a new light
because of this participation by which he is actually illuminated.
Thus the light of the student is intensified, because it becomes
more efficacious for understanding. 57

Baiiez, discussing the same magistral illumination, comes to
the same conclusion although he phrases it differently:
The principles on which a demonstration is based are the instruments of the natural light, inasmuch as the natural light of the
active intellect leads the possible intellect to assent to the conclusions under those principles by resolving the conclusion to those
first principles. Whence it follows that the master, by proposing
principles and means, properly strengthens the natural light of his
disciple, not, indeed, increasing it intensively but extensively, since
the natural light can now judge from the conjoined principles.
And so from the natural light, the principle and the mean, one
integral virtue is formed to judge of the conclusion. 58

This mode of illumination is of course impossible in the gift
of understanding, because we are not given any species by the
Holy Ghost to aid our understanding. But the whole process
of magistral illumination is important in order to understand
the next order.
The second order of beings, the angels, can illumine those
under them, whether angels or men, after the fashion of human
masters and also by directly strenghtening the intellectual
light of inferiors by uniting themselves with it. " Some say that
an angel in no way teaches like a person offering light, which
seems expressly against the words of Dionysius," 59 remarks
St. Thomas. 6 ° Cajetan seems to be among the " some," for he
describes and explains the angelic illumination after the manner
of teacher and pupil, in which " the light of the inferior is
intensified because more efficacious, although not properly
intensified." This magistral illumination, as we have seen, is
67 Oomm. in I, q. 106, a. 1.
•• Loc. cit.

•• De Ooelesti Hierarckia, c. X.
•• II Sent.. d. IX, q. l, a. 2, ad 4um.

THE NATURE OF THE GIFT OF UNDERSTANDING

281

only indirect illumination, inasmuch as there is no direct
tranfer of power or light but only a principle or a medium
which will excite the inferior to act. This is not sufficient for
Ba:iiez; according to him:
In the illumination of an inferior angel, his light is strengthened
not only by instruction but through an intellectual conjuction and
union by which the light of the inferior and superior are joined
together for one principle of knowledge of truth. 61

He is led to this by the teaching of St. Thomas-that the
teacher strengthens the intellect of the learner "not by an active
power as was said of the illumination of the angels ... 62
The mind of St. Thomas is, therefore, that the strengthening
of the light of the inferior angel is not only with respect to an
intelligible principle under which truth is manifested, but also
with respect to some action proceeding from the active virtue
of the superior into the inferior. St. Thomas teaches, moreover,
that illumination of an inferior angel depends on the superior
not only for reception but also for its conservation, just as the
knowledge of a conclusion depends on an actual knowledge of
the principles. 63 Therefore, there is required a natural influx
of the light of the superior into the illuminated; otherwise
knowledge of the inferior would be only in inception and not
in conservation, as the teaching of a master in the mind of his
student depends only in its inception on the master. The light
of the superior must stay with the inferior because the intelligible object by its very nature exceeds the light of the inferior.
Ba:iiez gives some examples of the union of diverse things
forming one principle of operation without losing their own
identity. The first is from color and light. Visible light does
not inhere in color, but the light in the air makes the color
in the wall actually visible, not only as the terminative object
of sight, but also the motive object. It is colored light that is
the unique integral principle · moving sight through visible
species, yet the light is not the color, for in vision there is a
natural subordination of color to light. There is another
81

Loc. cit.

u Summa Theol.• I, q. ll7, a. 1.

88

Ibid., q. 108, a. 7, ad 2um.

JOSEPH IGNATIUS

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example from goodness in the intellect and will. Apprehended
goodness, precisely as apprehended, is the formal motivating
force of the object of the will, and is the form and the act of the
will constituting with it one integral principle of volition, and
although it concurs to produce the volition, it does not really
inhere in the will, because of the natural subordination of the
will to the intellect. Finally, in any act of knowledge, the intelligible species is the result of the partnership of phantasm and
light of the active intellect, and yet the light does not inhere in
the phantasm nor cause anything in it. So, when a potency,
the intellect of an angel, is joined to a superior form, becoming
with it one principle, the potency can still vitally elicit its
proper operation with an increased power, intrinsically and
intensively.
The third order of beings who illumine man is God. God is
alone and unique in His power. He can swiftly and perfectly
enlighten man either permanently or for a time, not only by
the indirect methods of men and angels, but by directly increasing the intellective power of man. The light of man's
intellect in the first place is only a created participation, a
circumscribed ray of the uncircumscribed light of the supreme
!ntellect of God. 64 By the infusion of grace into the soul, man
is united to God, and as a result of this divine habit in the soul,
all its faculties are divinized and strengthened. As with all
things that only participate their perfection, the closer tJ.\ey
approach their source the stronger they become, and so the
intellect in approaching God becomes stronger. When the Holy
Ghost moves it, it seems to leave behind all the defects of
being joined to a body, and seems to become angelic in the
clarity of its intuitive judgments. Just as the inferior angel
under the illumination of the superior becomes able to understand objects that exceed its ordinary powers, so the intellect,
furnished with the light of the Holy Ghost in the gift of understanding, penetrates, grasps, and assents to supernatural truths
which would present an impenetrable front to its natural
•• Ibid., q. l!i!, a. !i!.

THE NATURE OF THE GIFT OF UNDERSTANDING

238

powers. Again, like an angel, this power remains in the intellect
only as long as the intellect is united to God by grace; once the
mover withdraws, man relapses into the obscurity of faith.
This in general is what is indicated to us by broadly comparing
the gift of understanding to light.
In the answers to the difficulties 65 St. Thomas starts to
distinguish this generic notion of supernatural light. From the
first, we gather only that it is superior to that by which we
know common principles, and from the second we gather its
intuitive super-rational and esssential character.
The natural light of the human intellect is of a quality or
a permanent form which makes it sufficient of itself to know
some proportionate object, but this is not man's only means
of natural knowledge. Joined to the light as instruments to a
craftsman are the first principles of knowledge. 66 They are the
first conceptions of the mind, known through and in their very
terms without any discursus or reasoning. With their help the
intellect is ready to apprehend and to penetrate its proper
object-essences. St. Thomas says:
There are different ways of apprehending essences. Sometimes the
essence is apprehended immediately and not through those things
which are wrapped around the essence; this is the mode of apprehension in separated substances, and so they are called intelligences. Sometimes again, the intimate core of a thing is not
penetrated except by the things around it as through some kind
of gateway; this is the mode of apprehension in men, who from
properties and effects proceed to the knowledge of an essence.
Because this process is discursive, the apprehension of man is
called reason, although it terminates at the understanding of a
thing, because its inquiry leads to the essence. Whence if there
are some things which are apprehended at once without the operation of reason, we say that these things are understood, and not
reasoned to; such, for example, are first principles which everyone
approves as soon as he, hears. In the first way, the intellect is a
potency, but taken in the second way, it is called a habit of first
principles. Just as the human mind, moreover, does not penetrate
to the essence of anything except through accidents, so also it does
•• Ibid., I-II, q. 8, a. I.

•• Q. D. de VeT.• q. 11, a. 8.

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not penetrate spiritual things except through corporeal things and
the likenesses of sensible things.
Whence it is that faith, which holds spiritual things seen as in
a dark glass, perfects the mind in a human mode and, therefore, it
is a virtue. If, however, the mind is so elevated by a supernatural
light that it is led to gaze upon spiritual things as they are in
themselves, this is beyond human power. This is what the gift
of understanding does; it so illustrates the mind concerning the
things of faith that like first principles, they are proved the minute
they are heard. This understanding is, of course, a gift. 67

Hence, when in answer to the second objection, 68 St. Thomas
says that the super-added light has the same relation to things
known supernaturally as natural light has to first principles,
he definitely indicates that the distinctive note of the light
of the gift of understanding will be the swift intuitive grasp
it offers of spiritual things, by the illumination of the Holy
Ghost without the burden of step-by-step reasoning.
By comparing the gift of understanding to the habit of first
principles in the natural order, St. Thomas does not mean to
institute a comparison of the instrumental relation so much
as to point out the nature of the act of the gift. The knowledge
of first principles is gained without inquisition and argumentation, in which point human knowledge touches that of the
angels although it does not equal it because we are still dependent on the senses.69
Indemonstrable principles are known at once, as soon as we hear the
terms, for as soon we know what a whole is and what a part is,
at once we know that every whole is greater than a part . . . and
so, the knowledge of principles which become clear as soon as the
words are known is conveniently called

It is easy to make a mistake here that will distort the whole
notion of the gift. Taking the words as they stand, it seems
that a simple apprehension of the terms of the first principles
is sufficient to generate the habit. Yet such is not the case.
•• III Sent., d. XXXV, q. 2, a. 2.
•• Summa Theol., I-II, q. 8, a. 1, ad 2um.
•• Q. D. de V er., q. 16, a. 1.
•• VI Ethic., lect. 5.

THE NATURE OF THE GIFT OF UNDERSTANDING

First principles do not consist in the mere apprehension of
terms, but in a composition of subject and predicate, an assent
and a judgment. The knowledge of " whole" and the knowledge of " part " is indeed a simple apprehension, but to say
that the whole is greater than its part is a judgment. This is
but an application of the general doctrine that truth is in the
judgment formally, and not elsewhere. 71 Like any other habit
in an active potency, there must be an act of assent before we
can acquire the habit of inclining us to do so.
Now, with the gift of understanding, all this is lifted into the
supernatural order. The light of this gift is not merely to
apprehend the terms in which supernatural truths are proposed,
but to apprehend correctly and then to compose and divide
and so arrive at the truth without, of course, any long process
of reasoning, which proceeds step by step until a conclusion is
reached. By the gift, the mind is perfected in the apprehension
of truth, not any apprehension, but that apprehension which
pertains to the way of invention. 72 Invention is not what we
understand by the term today, a novel application of the
principles of mechanics to some problem, but it
the name
applied to a process of finding truth. In this discovery of truth
we proceed in a human way from sense to memory, from memory
to experiment, from experiment to first principles which are known
immediately the terms are known; this process perfects the intellectual habit which is the habit of first principles. We proceed
further in the same mode by advancing from these principles to
conclusions. For this we are perfected in those things which are
under reason by another intellectual virtue which is called science;
in those, however, which are above reason, we have faith which is
the inspection of divine things seen, as in a dark glass. To grasp
what might be called the naked truth of spiritual things, is above
merely human powers, and requires the gift of understanding which
illumines the mind concerning those things heard through faith. 73

As John of St. Thomas says:
Invention does not concern the simple apprehension of terms, but
01 Summa, Theol., I, q. 16, a. 2.
n Ibid., 1-11, q. 68, a. 4.
•• Ill Sent., d. XXXIV, q. 1, a. i.

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inquires about some truth and the propositions that invention
attains; for some things we learn; some things we find and so attain
them, not learning them from others. What we learn are not simple
terms and the apprehension of them, but propositions and truths,
whether known from their terms or from argument; similarly,
therefore, what we attain by invention are not only simple terms,
but truths, and the propositions by which such truths are
enunciated. 74

From the answer to the second objection/ 5 where the process
of reason is contrasted with pure intellection, it is evident that
propositions-truths-are
meant, and not mere simple terms,
because in the process of reason we start from some proposition
that we understand and proceed by many steps to a conclusion,
another proposition, which is now known to us in the light of
the propositions we knew at first. By the light of first principles,
we understand not terms but propositions, truths known
through themselves, in which something is affirmed or denied
of something else, e. g., "Whatever is, is; a thing cannot be
and not be at the same time"; and the more subtle but still
self-evident truths like," there cannot be many gods." Equally,
then, by the light which is called the gift of understanding,
we can grasp with intuitive ease the supernatural meaning of
the objects of our knowledge. We shall now consider these
objects.
St. Thomas shows the objects to which the gift of understanding refers by analogy with the intuitions of the natural
faculty. There are six categories of hidden things which the gift
aids us to bring to light: the substance under its accidents;
the sense beneath the words; the truth behind the symbol;
the spiritual under its sensible appearances; the cause in its
effect; and the effect in its cause.
The first intuition is exemplified in the familiar story of
Blessed John Dominici and Antonino Pierozzi, known to the
world as St. Antoninus, Archbishop of Florence. What possessed the great Dominici, with his apostolic thirst for austerity
u Oursus Theologicus, I-IT, disp. XVITI, a. 8.
•• Summa Theol., I-IT, q. 8, a. 1, ad 2um.

THE NATURE OF THE GIFT OF UNDERSTANDING

237

and reform, to even compromise with the pale, sickly, motherless lad whom the doctors promised would soon die of consumption, and promise him admission to the Order of Preachers
should he commit to memory the Decretal of Gratian in a
year? He must have seen beneath that unprepossessing exterior
the stuff which properly handled would bring the glory of sainthood to the Order of the Church. Under the accidents he saw
the substance.
As for penetrating the sense of words and the spirit of the
letter, St. Thomas gives the example of the disciples at Emmaus
of whom St. Luke 76 says, " Then He opened their understanding, that they might understand the Scripture." Long
before he had said to His followers, " Are you yet also without
understanding ? " 77 This example of the disciples at Emmaus,
though traditionally cited by nearly all spiritual writers as an
operation of the gift of understanding, may lose something
of its force when we recall that St. Thomas also uses it in his
discussion of the gift of prophecy/ 8 where he calls it an example
of a charism pertaining to St. Paul's "understanding of instructions." If given as a transient vision by which certain
texts concerning Christ were momentarily illumined for the
good of the young Church, it is a charism, but if it is a habitual
quality remaining in the mind, then it is the gift. In the Acts,
mention is made of Lydia, the prototype of all those pious
souls " whose heart the Lord opened to attend to those things
which were said by Paul." \''9 Many of the saints found in the
highly symbolic language of the Old Testament the expression
of their hidden mystical joys and delights. St. Thomas confessed," Never have I read a book that the Holy Spirit has not
aided me to comprehend it, and to plumb the profundity of a
mystery." 80 St. Antoninus places his whole discussion of the
interpretation of Scripture under the title of this gift.
It is the gift of understanding that makes us see the spiritual
•• Luke, xxiv, 25.
•• Matthew, xv, 16.
•• Summa Theol., 11-11, q. 173, a. !il.

•• Acts, xvi, 14.
80

Tocco, vii, 40.

JOSEPH IGNATIUS

MCGUINESS

reality behind its sensible appearances. The villagers of
Nazareth saw only a poor young carpenter laboring in a shop,
but Mary, his Mother, saw not only the most perfect human
soul that ever lived; she saw her God. This " seeing " is not
through any medium, like a sign or a mirror or a footprint or
an image, which usually links the apprehensive power and the
thing signified; it is accomplished by the superabundant light
of the gift of understanding, just as the light of the sun joins
the power of sight and the thing seen.81
The world saw a common criminal dying between two of his
kind on Calvary, but His mother with the eyes of her soul
saw the redemption of the world depending on that sorrowful
passion, and so she held herself upright at the foot of the Cross,
and instead of sinking in the human grief of the holy women, she
stood and shared the redemption of the world. Indeed, in the
Blessed Virgin we :find this gift in a more perfect degree than in
any other creature. As soon as the Angel announced to her
the part she is to play in the redemption, she responded " How
shall this be?" This was not disbelief, but the gift seeking to
penetrate and to see the plan of God. Some writers attribute
the Magnificat to this gift, since her clear perception of her
prerogatives and her supernatural vocation so elevated her
heart that it could not contain its joy. St. Albert, however,
attributes the Magnificat to the gift of wisdom, because of his
notion of the gift of understanding. 182 This is how he describes
the gift in Mary:
The gift of understanding is to know God in His image. Between
knowing God in His image, without light, in the obscurity of faith,
and knowing the uncreated light by uncreated light, without an
image, there is a middle way to know in created light, without
an image. Just as one of the extremes is of pure wayfarers, and the
other of those in Heaven, so the middle pertains to the state in
which Our Blessed Mother was. She, therefore, had this gift more
perfectly than other creatures. 83
St. Antoninus, Summa moralis, IV, tit. 15, c. 18.
•• Comm. in Evang. Lucae, i, 46. Opera Omnia (Paris: 1890-1899), XXII,
•• Mariale, q. 64. Opera Omnia, XXXVIT, UO.
81

THE NATURE OF THE GIFT OF UNDERSTANDING

239

The saints too, knew how to see in every human creature the
soul made to the image and likeness of God, and very often the
Holy Spirit dwelling there. " Henceforth," says St. Paul, " we
know no man according to the flesh." 84 There is a remarkable
example of intuition in the life of St. Catherine of Sienna,
when she prepared Nicholas di Toldo for his execution and
accompanied him to the scaffold.
The knife fell and I receive his head into my hands. I fixed my
eyes on the Divine Goodness, and Lo ! I beheld as clearly as one
beholds the sun, Him who is God and man. He was there and He
received the blood . . . He received it and placed it in the open
wound of His side, in the treasury of His mercy . . . Oh how
lovingly He looked on that soul bathed in the blood made precious
by being united to His own! Then Father, Son and Holy Ghost
received him, and He was inundated with a joy that would have
ravished a thousand hearts . . . Then I felt a delicious peace,
and the perfume of that blood was so sweet to me, that I would not
suffer them to wash away what had fallen over me.85
In this blood united to Christ through grace, Catherine saw the
blood of the Lamb, and sought to plunge herself into the
Sacred Side. So many other examples of the operation of this
gift in an eminent degree are to be found in the life of this holy
daughter of St. Dominic that Fr. Antoine Gardeil attributes
this gift to her as her predominant characteristic: 86
By natural reason most men come to a knowledge of the
existence of God, but by the light of revelation we know that
God is one in three divine Persons. By the light of the gift of
understanding we go on to contemplate in the Holy Trinity
as far as we can in this life, what are the relations of Father,
Son and Holy Ghost, how they are three Persons, how they
are co-equal, co-eternal, how they differ only in their relations
to each other, and so on. As Cardinal Manning says," The one
phrase, ' the Word was made flesh,' contains the whole theology
•• II Cor., v, 16.
•• Letters, n. 97.
•• The Gifts of the Holy Ghost in Dominican Saints, Trans. by A. Townsend,
O.P. (Milwaukee:

Bruce, 1987), p. 88.

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JOSEPH IGNATIDS

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"Of the Incarnation in all its treatises." 87 We see it expanded
in the course of time-in the phrases of the Nicene creed:
"God of God; . . . consubstantial with the Father"; in the
Athanasian creed, with its more precise terms-the two natures,
two substances, one Person, perfect humanity; and in the third
part of the Summa and all the later theologians. Yet many a
humble soul knows just as much as the theologians without all
this study and science, like the monk Anthony of whom St.
Augustine speaks.
It is in the light of this gift that the poor and untutored
solve the apparent difficulties of belief. To those who judge
by the letter, or by outward facts, the sorrows and the miseries
of the world seem to obscure its witness to the goodness if not
the existence of God; the sorrow and miseries of the Church
likewise seem to deny it is the kingdom of an all-powerful God;
the evergrowing conquests of natural science are bent by some
against the truth of revelation. How find the unifying thread
of truth in all the advancements of our age unless by the superhuman light of the Holy Ghost? To penetrate all these chaotic
and disturbing elements and find at their core the calm and
majestic plan of God requires more than mere reason, handicapped as it is with distractions and imperfections. It requires
the additional light of the gift of understanding to pierce the
rind and find the sweetness of the fruit, to crack the shell and
find the kernel of truth. 88 Whence it is evident why spiritual
writers call this the gift par excellence of preachers and doctors
in the Church.

III.

THE GIFT AND FAITH

God has presented man with a sheaf of supernatural truths
which he must know and act upon in order to reach his final
end, and yet which exceed his natural powers of understanding.
By faith, man accepts these truths and holds them firmly, yet
it is an exterior adhesion in which the will bears all the expense,
87

H. E. Manning, The Internal Mission of the Holy Ghost (New York: Kenedy,

1904), p. 272.
88

Cf. M.-J. Friaque, 0. P., Le Saint-Esprit, Part ill, c. 7 (Paris: 1886).

THE NATURE OF THE GIFT OF UNDERSTANDING

241

the intellect remaining dissatisfied. Then, under the impulse
of the Holy Spirit, the man with the gift. of understanding finds
himself able to face these notions of revelation as easily as first
principles in the natural order. He has found a new light
enabling his mind to penetrate and to seize them quite clearly.
How reconcile the shadows of the faith with the luminous
evidence of the gift of understanding ? With the operation of
the gift, is the faith going to disappear ?
The reply is, of course, in the negative. By distinguishing the
formal aspects of the objects of the virtue and the gift, we see
how they can work side by side in the same subject without
interfering with each other in this life. Faith has three formal
objects. Its primary one is the revealed mysteries to which it
clings and about which no positive intuition is possible in this
life.89 The secondary object of faith is all the species of truths
concerning creatures as ordained to God, and here the more light
the better for the faith. Faith is said to have a third object
only by extension, that is, inasmuch as it operates through
charity in all moral acts. 90
As Father Garrigou-Lagrange writes,
Faith makes us know God in a way which is still too abstract, too
exterior, in speculo et in aenigmate, by excessively narrow formulas
that must be multiplied. Hope and charity directed by faith share
in the imperfection of faith. These two virtues of the will lack
vitality and keep too much of the human manner as long as they
are directed only by reason illumined by faith.
With only the virtues, even though supernatural, man is like an
apprentice who knows fairly well what he must do, but who has
not the skill to do it in a suitable manner. Consequently the master
who is teaching him must come from time to time, take his hand
and direct it so that the work may be presentable.
As we always remain apprentices the Holy Ghost must intervene
habitually in our works that they may be perfect. That is why,
unlike purely gratuitous graces, the gifts which make us amenable
to divine inspirations as the virtues do to the directions of reason,
should be permanent in us. (Summa Theol., I-II, q. 68, a. 3.)
••
Theol., IT-IT, q. l, a. 1.
•• Cf. Dictionnaire de Theologie Oatholique, Vol. 4, part

5

col. 1748.

JOSEPH IGNATIUS

MCGUINESS

A soul can advance by the exercises of the virtues. In this it is
active. Or by the inspiration of the Holy Ghost who breathes where
and when He wills. Here the soul is docile, acting less than it is
acted upon.91
St. Thomas says:
The gifts are given in aid of the virtues by which the potencies
of the soul are perfected to acts proportioned to a human mode,
like faith which sees but only cryptically in a mirror .. ;92
The defects in a virtue are twofold. There are accidental
defects, springing from some indisposition on the part of the
virtue, which are remedied by augmenting the virtue. The more
serious defects are the ones essential to the habit. This defect
is remedied by a higher habit which is called a gift because
given by God and exceeding the manner of human operation,
like understanding which brings it to pass that we see in some
way the things of faith clearly and limpidly. The defects of
the faith come from the very constitution of man;
His knowledge of faith has its origin in the sense, inasmuch as he
knows the meaning of words proposed by the senses, but these fail in
the representation of Him about Whom faith is primarily concerned. Faith, therefore, has not perfect knowledge.113
To faith pertain properly those things whose vision we shall
enjoy in eternal life and through which we are led therc. 114 The
only way we can attain them in this life is be believing, i. e.,
by having the will, on the authority of God, force the intellect
to assent. " The argument from divine authority does not make
the thing evident in itself." 95
The believer, who by the very fact that he believes does not
see, is liable to confuse the sensible element with the spiritual,
and fall a prey to illusions and errors. What knowledge he has,
moreover, is bound to be superficial and fragmentary. He must
01 Christian Perfet:tion and Contemplation, Trans. by Sr. M. Timothea
Doyle,
0. P. (St. Louis: Herder, 1987), pp. 281 fi'.
•• In Isaiam, xi, 2.
•• Ill Sent., d. XXIV, q. 1, a. 2, qt. 8, ad 8 um.
•• Summa Tkeol., II-II, q. 1, a. 7.
•• Ibid., q. 4, a. 1, ad -5um.

THE NATURE OF THE GIFT OF UNDERSTANDING

248

search around and reason about the formulas which contain
supernatural truth, unlike the angel who with a glance penetrates to the interior of things. Nor is the mind at rest,
satisfied in this knowledge. "The perfection of assent is caused
by the simple light of faith, but since this light is not perfectly
participated, the imperfection of the intellect remains, and so it
remains unquiet." 96 Finally, our love of God must partake
of the imperfections of our faith; it is easier to love what we
see than what we do not see.
The gift, because of its superhuman mode of action is free
from these defects, and when found in the same subject can
supply for the deficiencies. With regard to the confusion of the
spiritual with the sensible, St. Thomas says:
There are two sorts of cleanness, one dispositive and a preamble
to the vision of God, which is the purification of the affection from
inordinate affections, and this is carried out by the virtues and the
gifts in the appetitive faculties; the other cleanness of the heart is
complementary, as it were, to vision, and this is the cleansing of
the mind from phantasms and errors, in order that those things
which are proposed of God be not taken after the manner of
corporeal phantasms nor according to the perversion of heretics,
and this cleanness is the work of the gift of understanding. Therefore, under the aspect of merit, the sixth beatitude, " Blessed are
the clean of heart, for they shall see God," pertains to this Gift. 97
ll"'rom what we have said of the nature of this gift as a light,
this is easy to see. The mind under the impulse of the Holy
Spirit is helped over and past the obstacles of imagery to reach
the truth at the heart of the propositions.
The superficial and fragmentary nature of the knowledge of
faith is assisted by the instinctive and clairvoyant flashes of
the gift, with this reservation:
We can understand a thing in two ways: in one, perfectly, when
we attain to a knowledge of the essence of the thing understood
and the truth of the statement understood (enuntiabilis intellecti)
according as it is in itself; in another way, something happens to be
•• Q. D. d6 Ver., q. 14, a. 1, ad 5um.
•• Summa Theol., II-IT, q. 8, a. 7.

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JOSEPH IGNATIUS

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understood imperfectly when the very essence or the truth of a
proposition is not known as to what or how it is, but nevertheless
it is known that those things which appear externally are not contrary to the truth, inasmuch as man understands that he must not
recede from the things of faith, because of what appears extrinsically ."98
The precise role of the gift of understanding then will be to
aid the virtue of faith to overcome this defect without destroying its essential characteristic of blind assent. " Faith
implies only an assent to propositions, but understandng implies
a certain penetration of the truth." '99 This is seen by applying
this distinction to what we have said above concerning the
objects of faith. The gift .does not give a perfect and positive
insight into the principles and primary object of faith, but only
a negative and imperfect one, attacking the external impediments and obstacles that, by the very fact that we are still in
the state of wayfarers, separate us from God. Yet even here,
St. Thomas does not hesitate to say, " Even in this life, God can
in some way be seen, the eye [of the mind] being cleansed by
the gift of understanding." 100 Between God and ourselves are
interposed the sensible formulas of revelation. But illumined
by the light of the Holy Ghost in this gift, they become as it
were transparent. As St. John of the Cross writes in the twelfth
canticle:
Then
the soul call the faith crystalline because it makes the
soul to see through the now transparent veils, the Saviour of men,
because it is pure, clean of errors, empty of corporeal images,
strong in divine truth.
With Thy light Thou dost illumine me so that I may know all
Thy truth; Thou art that Light above all light, which illuminates
supernaturally the eye of my intellect, clarifying the light of faith
so abundantly and so perfectly that I see that my soul is alive,
and in this light receives Thee the true light. 101
•• Ibid., q. 8, a. S.
•• Ibid., a. 5, ad Sum.
100 Ibid., 1-11, q. 69, a. 2,. ad Sum.
101 Dialogues, Trans. by A. Thorold
(New York: Benziger, 1907), c. 167.

THE NATURE OF THE GIFT OF UNDERSTANDING

As to the substance of the mysteries, we can perceive sometimes the motives of them, connections one with another,
analogies, and their many harmonies. 1 {)2 Further than this we
cannot go concerning the essence of God and the mysteries
concerning Him directly.
Even the imperfect knowledge that the gift offers is a great
aid to faith, for by it, the little ones of the flock see that all the
apparent difficulties are invalid. Even when one does not always
know how to reply to objections, one knows that in spite
of the multiple and complicated claims of error, the truth
is there in its simplicity and its certitude. While heresies
and negations based on scientific formulas try in vain to take
the citadel of the fervent soul by assault, the soul intuitively
clings to Catholic dogma. This is the explanation of the not
infrequent phenomenon of the remarkable insight and appreciation of spiritual things found in unlettered and dullwitted men and simple women in whom however faith and
charity flourish in a high degree. To these simple souls, neither
the speculations of theologians nor the divine reasons are
explicitly known; but by the gift of understanding they are so
convinced of divine truths and so strengthened in the faith,
that they are not in the least perturbed by the sophisms of
heretics, the threats of tyrants, or the insidious snares of malignant spirits. Here, too, we see these rustic saints and humble
women spending long periods in divine contemplation, scarcely
able to interrupt most sweet colloquies of internal prayer and
quiet; we see them able to deliver sound and integral judgments
in doubtful matters because their appetites are correct; we see
them savor eternal things and spurn the temporal. They rightly
appreciate divine things, because their minds are crammed
with the consideration of divine truths hidden from the wise
and prudent and revealed to the little ones, for, as Christ and
the Holy Ghost tell us, the conversation of God is with the
simple-hearted. 1 {) 8
Billot, op. cit., p. 185.
Cf. V. Contenson, 0. P .., Theologia Mentis et Cordis, Lib. VIII, Diss. II, c.
Spec. 2 and 3 (Paris: Vives, 1875), ill, 526 fl'.
10 •

108

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As for the secondary objects of the faith, " the effects of the
Divinity through which man is helped to tend to divine fruition,
Holy Scripture, for example, and all it contains," 104 access to
such truths as these lies open through study, or through the
teaching of other men, but, in a higher and easier and more
salubrious mode, through the instinct of the Holy Ghost 105 " I am he that in an instant elevates a humble Inind to understand more reasons of the eternal truth than could be acquired
by ten years' study in the schools." 106
The assent of the intellect to truth is of two kinds: in one
the intellect is moved by the object whether it be known in
itself, as in first principles; or in the light of other principles and
The object, in other words, is really seen by the
intellect, because it itself moves the faculty to knowledge. In
the other way, it is moved not by intrinsic evidence on the part
of the object, but by the will.107 The intellect cannot be deterInined either by the simple inspection of the terms of a credible
proposition as by principles, nor from the light of other principles as in demonstrative conclusions. The will, however,
chooses to determine the intellect, because of something sufficient to move the will but not the intellect. This is to believe.
One believes the words of some man because it seems proper
or useful, or, especially, when a reward of eternal life is
proinised.
The act of belief is unique among the acts of the mind. In
the mere apprehension of things there is no assent, because the
truth is not grasped as such, and assent is only the truth. In
one who doubts, there is no real assent, nor is one who has only
an opinion. The man with the habit of first principles assents
to them, but without collation and therefore without a sort of
reiterated intellectual activity called cogitation. The man with
the habit of conclusions has both cogitation and assent, but the
cogitation is the cause of the assent, inasmuch as from the
Summa Theol .• II-II, q. 1, a. 1.
Cf. Billot, loc. cit.
106 Imitation
of Christ. Bk. III, c. 43, n. 3.
101 Summa Theol .• II-II, q. 1, a. 4.

10 •

105

THE NATURE OF THE GIFT OF UNDERSTANDING

collation of principles and conclusions, he resolved his conclusion into its principles, and now his intellect rests. In science
the motion of reason begins with the habit of principles and
ends in them.
Cogitation and assent are not equal because cogitation leads
to the assent and stops satisfied. In faith alone are cogitation
and assent equal. Assent is not from the cogitation at all but
from the will, but because the intellect is not in this manner
terminated to one part of a contradiction as to its proper termthe vision of something intelligible-it remains unquiet. Its
motion has no term and it still has a cogitation and an inquisition
about what it believes. Whence it is that the intellect of a
believer is said to be captive 108 because it is bound by another's
terms as another's, and not as its own. Whence it is that there
can arise contrary motions to that which it believes, unlike the
states of understanding and science.109
The gift of understanding is a light added to the natural
power of the intellect, enabling it to penetrate the truths of
faith. Its formal characteristic is to apprehend and to know,
whether perfectly or imperfectly. To understand, as distinguished from to believe, is always with some intrinsic evidence,
whether positive or negative. The fact that in this life we do
not attain perfect vision is not due to any defect in the gift
viewed from its proper formal aspect, but because the matter
is not duly disposed so that it be seen in itself, " for we walk by
faith and not by sight." 110 Since the gift moves the mind,
according to the illustration of the Holy Ghost, to rightly
penetrate and understand things proposed to it, it demands
evidence of itself and from its formal note, and takes it as far
as it can from the matter proposed to it, positive and perfect
in heaven, imperfect and cryptic in life under the shadows of
faith. 111
II Cor., x, 5.
Q. D. de Ver., q. 14, a. 1.
110 II Co-r., v, 7.
111 Cf. T. A. Vallgornera, 0. P., Mystica Tkeologia (Turin: Marietti,
89!!, n. 559.
108

109

I,

JOSEPH IGNATIUS

MCGUINESS

Now, this evidence is just what the intellect lacks in faith.
The gift penetrates the very terms from which the truths of
faith are constituted and discerns between truth and falsehood,
between spiritual and corporeal things. It understands that
spiritual things are not such as we gather from our phantasms
and that, consequently, we must estimate them much higher
than we see and know them to be. The gift of understanding,
therefore, brings a certitude or a quietude in matters of faith.
For this reason the faith which is a fruit of the Holy Ghost
corresponds to the gift of understanding; the habit or theological
virtue of faith is not the fruit of the gift, but a certitude of mind
and a rest in the faith is this fruit. To the gift, therefore,
pertains not a mere judgment of faith and assent, but a discernment of spiritual from material, supernatural from natural,
truth from error, which it can achieve evidently, by at least
negative evidence. " The gift of understanding is born to
perfect every intellectual perception regarding faith, whether
it precedes or follows the gift." 112
The fact that the object of faith remains obscure shows that
the idea of light and illumination of the gift must be modified
to some degree. It is not a light in the sense of glory, or even
of faith's obscure light, but a limited capacity for the illuminating instincts of the Holy Ghost. The reason for its limitation,
however, is not intrinsic to it; the motion of the gift is to see
and penetrate under the instinct of the Holy Spirit. The fact
that only when we have received the light of glory will we see
God is what limits the lengths to which the Holy Spirit can
impel us. The gift of understanding precisely as understanding
implies vision, perfection, clarity. It is on the part of the object
and the subject while the state of faith endures that the limitation comes.
We must recall here what St. Thomas has written on the
relation of the gifts to the virtues. He readily admits the
superiority of the gifts over the intellectual and the infused
moral virtues, because of the superiority of the motive power
u• Cajetan, Comm. in II-II, q. 8, a. 7.

THE NATURE OF THE GIFT OF UNDERSTANDING

fl49

in the former. But in comparing the theological virtues with
the gifts, the latter must cede their place of eminence because
it is more noble to be united directly to God by the virtues
than to be moved obediently to that end by God, just as a man
who already has his million is richer than another still working
and saving for it. Faith is a regulative principle which even
the Holy Ghost respects, and the obscurity of faith is the check
on the illumination of the gift of understanding.
Given an object not too sublime for its powers, however, the
gift can do a perfect job. This object is, as we have seen, the
secondary objects of faith, that is, all the truths concerning
creatures as directed to the first truth. Holy Scripture and the
history of the church are full of truths which we can understand
perfectly. Examples are not wanting among the saints. St.
Augustine tells us of how he sometimes received an instinctive
and clear knowledge of a passage of scripture he had read many
times before without perceiving there anything special. St.
Teresa in her life naively tells of how much that she wrote
seemed to be coming from someone else who understood it
much better than she, 118 and that often, without knowing how,
she understood the most profound verses of the Psalms while
saying office. Many souls ignorant of human science find in the
Scriptures meanings which escape the laborious investigations
of exegetes and theologians. The writings of St. Catherine of
Sienna, of St. Teresa, and in our day the pious and profound
reflections of Sr. Elizabeth of the Holy Trinity, a Carmelite of
Dijon, on the writings of St. Paul show that these matters may
be understood. We have already seen other examples of the
intuitions of this gift.
To summarize: The gift of understanding has the same
cause as the virtue of faith, God and grace; the same objects
to penetrate as the faith to believe, the divine truths; the same
medium of knowledge, the formulas of revelation. It differs
from faith in its mode of knowledge which is divine in the gift
and human in the virtue, and in its proper and specifying act
118

Life. c. 14..

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which is to assent on the authority of God in the virtue and
to apprehend and to judge on evidence of truth and falsity in
the gift.
" Faith works through love," says the Apostle/ 14 and throws
the whole field of human actions into the lap of faith. Besides
its material and formal object, faith extends to the whole field
of Christian practice, regulating it and drawing from the
formulas of revelations luminous rules for the conduct of life
which can be found nowhere else. The intratrinitarian relations,
for example, provoked the saints to realize in themselves the
virtues of which the relations are the exemplars. In other words
they sought to make practical, workable, operable, the abstract
and conceptual expressions of the faith. 115
0 Holy Trinity I have known in Thy light, which Thou hast
given me with the light of Holy Faith, the many and wonderful
things Thou hast declared to me, explaining to me the path of
supreme perfection, so that I may no longer serve Thee in darkness,
but with light, and that I may be the mirror of a good and holy life,
and arise from my miserable sins, for through them I have hitherto
served Thee in darkness. 116

Wherever the faith extends, so must the Holy Ghost assist
with his gift of understanding.
The gift of understanding extends also to certain actions, not as
though these were its principal object, but insofar as the rule of our
actions is the eternal law.117

We must be careful here not merely to note the argument and
conclusion and pass on, because such a course will lead to a
confusion of the gifts later on. The reason for the apologetic
tone in extending the gift to operations is that it stretches the
nature of the gift beyond intuitive inspection and judgment
of matters of faith. To say that the gift extends itself is only
a manner of speaking because understanding no less than the
Gal., v, 6.
Diet. Thea. Oath., art. cit., col. 1743.
118 Dialogues, loc. cit.
117 Summa Theol., ·II-II, q. 8, a. 3.
114
115

THE NATURE OF THE GIFT OF UNDERSTANDING

251

other gifts is primarily a passive habit, a disposition to follow
promptly the instinct of the Holy Ghost. Just what particular
gift prompts us to follow this motion depends upon the term
to which we are moved.
It appears that even St. Thomas had difficulty in determining
the distinctive role of each of the intellective gifts, so closely
are they joined in charity. In his consideration of understanding
he revises what he had written on the gifts in general, and yet
seems to confuse wisdom and understanding, judgment and
perception. 118 There is only one phase of ou:r moral actions
where the gift of understanding as we know it can operate.
This operation consists in penetrating and grasping the provisions of the eternal law, which exceeds our natural reason,
and in discovering in our human acts those regulations. 119
Once these principles are known, it is the office of wisdom to
apply and to order them to our actions. This is his express
teaching when he comes to treat ex p7ofesso of the gift of
wisdom. In answer to the question whether wisdom is solely
speculative or also practical, he answers:
. . . the superior reason is deputed to wisdom, the inferior to
science. The superior .... looks to supernal, that is, divine,
reasons both by considering and by counseling, considering indeed
according as it contemplates divine things in themselves, counseling
moreover according as through divine things it judges of human
acts, directing hu'11ULn acts by divine rules. Thus therefore wisdom
as it is a gift from the Holy Ghost is not only speculative but
practical.

And in the answer to the third objection:
.. to wisdom pertains :first a contemplation of divine matters
which is a vision of the principle; and afterwards to direct human
acts according to divine reasons. 126

St. Thomas had a special difficulty in this whole question.
It is the first of his particular considerations of the gifts, and
he had nothing except general notions to use. As he progressed,
118

Ibid.

119

Ibicl., ad Sum.

120

lbicl., q. 45, a. 8.

JOSEPH IGNATIUS

MCGUINESS

he could use what he had written previously on other gifts for
comparison and contrast, but here some confusion is inevitable. He insists however that the gift of understanding is
primarily speculative, that is, ordained to the apprehension of
truth, for the sake of truth and nothing more. For the rest,
we can interpret him to mean that the gift of understanding can
enter into the regulation of moral actions insofar as the knowledge of the meaning of the principles- of such actions can be,
but not necessarily always is, due to the gift of understanding,
while the actual regulation, and so forth, is left to the other
gifts and virtues.
Another source of possible confusion is the fact that the
faculty which the gift of understanding perfects is the superior
reason, a faculty perfected also by the gift of wisdom. But
St. Thomas notes that there are two acts in the intellect, perception and judgment. 121 The former is perfected by understanding
and the latter by wisdom and science.
A good idea of the exalted role of this gift in our life can be
gathered from considering just what faculty of the mind it
perfects. The superior reason is, for St. Thomas, and before
him for Augustine and Dionysius, that part of the intellect
which contemplates the things of God. It is not that the
intellect, being a simple, immaterial faculty, has parts, but that
it has different relations to various objects giving it different
acts which only appear to proceed from different faculties.
The superior and inferior reason are distinguished thus:
There are certain natures superior to a rational soul, others inferior.
Since, moreover, everything understood is after the manner of the
one understanding, the knowledge of superior things in the soul is
inferior to the things themselves; but of inferior things, the knowledge of them is superior because in being known they have a more
noble state of being than in themselves; and so there is a different
relationship to both, and different offices. For according as it looks
to superior natures, either contemplating their truth and nature
absolutely, or drawing from them a reason and a quasi-exemplar
of action, the reason is called superior reason; according as it looks
111

Ibid., a. !il, ad Sum.

THE NATURE OF THE GIFT OF UNDERSTANDING

to inferior things either to be scrutinized in contemplation or to
be disposed through action, it is called inferior reason. Each
object, superior and inferior, however, is apprehended by the human
soul according to the common note of intelligibility; the superior,
as it is immaterial in itself, the inferior according as it is stripped
from matter by the act of the active intellect. 122
And to show its dignity:
. . among creatures such is the order that first are the angels
and secondly the rational soul. Because the rational soul is joined
to a body, the knowledge due it according to its own proper order
is a knowledge which proceeds from sensible to intelligible things,
and does not arrive at a knowledge of truth, except by a previous
inquisition. Its knowledge, therefore, is called rational, but because
the angel is purely incorporeal, not united to a body, the knowledge
due his nature is truth apprehended without inquisition. Because
of this he is called an intellectual nature. It is fitting, moreover,
that in the human soul which is configured to the angels in the
order of creatures, there be some sort of participation of intellectual
power by which it apprehend some truth without inquisition, just
as naturally known first principles are apprehended in speculative
and practical matters . . . This power is conveniently called the
spark for as a spark is a bit of light flying up from a fire, so this
power is some small participation of intellectuality, in comparison
to the intellectuality of the angels. 128
From the supreme part of rational nature, St. Thomas turns
next to the supreme part of super-nature, grace and charity.

IV. THE GIFT AND GRACE
St. Thomas now comes to consider the relation of sanctifying
grace and the light of understanding. He treats the questions
from two angles, deciding in the fourth article that all who are
in the state of grace have the gift of understanding, and then in
the :fifth 124 because of the fact that faith is in those without
grace, he further determines that only those in grace have the

gift.
Q. D. de Ver., q. 15,
II Sent., d. XXXIX, q. 3, a. 1.
12 • Summa Theol., IT-IT, q. 8, a. 4 et 5.

122
123

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JOSEPH IGNATIDS

MCGUINESS

By the infusion of sanctifying grace into the soul, the human
will is rightly directed to the good. But because of the subordination of the will to the intellect, to be rightly directed to
anything the will must first know it, or at least, of it. Therefore,
the presence of grace requires some knowledge of the end, but
as Cajetan, commenting on this article, immediately asks, why
is not faith sufficient to supply that knowledge ? It is because
of its imperfection which affects charity, as St. Thomas insinuates by bringing charity into the question in the very next line.
If you ask why cannot faith informed by charity furnish enough
knowledge, in answer Cajetan cites faith's imperfect participation in the divine lightSince an inferior participates to a lesser degree what is found in a
superior, the light of faith, in bringing about the proper estimation
of things in an intellect moved by a perfect will, is, as it were,
intensified by the intensified light of the gift. A sign of this is that
informed faith differs from formless faith, not on the part of the
intellect, but on the part of the will. Since, then, formless faith lack
the proper estimation of things which is found with informed
faith, and this proper estimation belongs to the intellect, it is
evident that this other light, that is of the gift of understanding,
is added to the light of faith. 125

Whence it becomes apparent that charity is of great importance
in this question. It is the medium of the demonstration that
properly concerns the gift, for as St. Thomas says:
Just as the Holy Ghost through the gift of charity orders the will
of man in order that it be directly moved to some supernatural
good, so also He illumines the mind of man that he might know
some supernatural truth, to which the right will should tend.
Therefore, just as charity is in all in the state of grace, so too is
the

The gifts are all infused into the soul at the same time as
sanctifying grace, as St. Thomas will later teach. 127 Besides, as
Maritain says:
125

126

Cajetan, Comm. in II-II, q. 8, a. 4.
Summa Theol., II-II, q. 8, a. 4.
Ibid., ill, q. 62, a. 2; q. 69, a. 4.

THE NATURE OF THE GIFT OF UNDERSTANDING

255

Grace confers on us supernaturally the radical power of grasping
the Infinite as object of our intellect; it gives us a new source of
spiritual activity which has for its proper and specific object the
Divine Essence seen in itself. By the vision to which grace proportions us radically, the creature becomes true God Himself, not
substantially, but in the sense that it achieves that immaterial
union which comes of the act of understanding. 128
By grace and the theological virtues God is rendered personally present to the soul. Even with the virtues of faith, hope,
and charity, man is still a defective and at times impotent
agent in this new order, and so God comes personally to elevate
and direct him to his proper place. God's suave and harmonious
way of doing things has placed in man qualities which dispose
him to receive and to correspond with His motion, and which
are proportionate to the virtues which rendered God present
to the soul and, as it were, gave Him the opportunity for
working it it. These are the gifts of the Holy Ghost. 129
Our charity renders us desirous of knowing God as He is,
but this insistent curiosity is unable to tear aside the veils which
prevent us from knowing Him immediately. Charity to be
perfect, to be efficacious for salvation, requires knowledge,
because the will is so constituted that if it is to wish well and
correctly its object must be clearly seen and so presented to it.
But it is not the nature of faith to know clearly. The knowledge
that comes to us from the Church, Holy Scripture, the Fathers
and Doctors of the Church is inadequate to translate to us the
life of an Infinite Being with transcendent and ineffable perfections. Our intelligence, far from pentrating at first sight the
affirmations of the faith, falls back in incomprehension. To
think of God and to represent to ourselves what He is in Himself, we must try with great effort to transpose to Him the
perfections of created realities and, as we have seen, we are
prone to fall into material, temporal, and human notions. 130
128 Quoted by B. L., "Philosophie et experience mystique," in La Vie Spirituelle,
Mai, 1926 (Suppl.), p. 167.
uo T. Pegues, 0. P., Commootaire de la Somme Tkeologique (Toulouse: 1907-81),
IX, 844.
uo H. 0. Noble, 0. P., "Les dons du Saint-Esprit auxiliaires des vertus morales,"
in La Vie Spirituelle, XVI (1927), it6.

JOSEPH IGNATIUS

MCGUINESS

The Holy Ghost, already in us by charity, supplies for the
deficiencies of our knowledge, and fills our need for more knowledge by elevating our minds to new discernments and new
judgments in the intellectual gifts. Hence it is the demands of
charity, but imperfectly met by faith, that are the raison d'etre
of the intellectual gifts. This is the meaning of St. Thomas here
and accords with his teaching that the gifts are so joined together in charity, that no one can have charity without them
and no one without charity can have them. 181 So, in a special
sense, understanding is a light super-added by grace.
The presence and operations of the gifts seem to be closely
connected with foreknowledge and predestination, sufficient
and efficacious grace. At the time when sanctifying grace is
infused into the soul, the seven gifts of the Holy Ghost are also
infused to constitute a perfect super-natural organism ready
to be moved by the Holy Ghost in a manner beyond all human
consideration. The Holy Ghost working freely activates His
gifts in some souls and leaves them dormant in others," for the
Spirit breatheth where He will," as our Lord said. 132 His
instinct causes in us an action which is at once free, and therefore meritorious and infallible. That is to say, under His
impulse we shall elicit acts which lead to salvation, and so the
predestined are infallibly led to their goal. Faith, though it is
a light making us see what we are to believe and uniting us to
God in knowledge, is, nevertheless, in a deficient human faculty.
The cogitation of which we spoke is unsatisfied, and its contrary
motions may elude the rule of the will, so causing even the will
to falter in its adhesion to God in love. Once the will is shaken,
the other obstacles which are always present in man can gain
strength and overthrow the subordination of man to God; sin
with the loss of grace is the result.
Hence, to heal the deficiencies in the union of the mind to
God in faith, and in a sense, to insure that the actions of this
mind will procure its salvation, the Holy Ghost must operate
in that soul by the light of understanding, or it is lost. "Hence,"
181

Summa Theol., 1-11, q. 66, a. 8.

18 "

John, iii, 8.

THE NATURE OF THE GIFT OF UNDERSTANDING

257

as St. Thomas says, " the gift never withdraws from the saints
in things necessary to salvation." 133 As Billot pithily puts it:
... from the fact that habitual grace is not only necessary that
man in the present state avoid sin, but also sufficient that he operate
meritoriously, it does not in the least follow that it is sufficient to
avoid sin and to persevere in justice once attained through the whole
time of this laborious way . . . and the principal reason is that
integrity of nature is not restored by habitual grace . . . Therefore
as the Angelic doctor teaches a man in grace needs the aid of actual
grace that he be moved by God to act rightly, because of the
condition of the state of human nature. There remains a certain
obscurity of ignorance in the intellect; we cannot fully know that
which is expedient for us, "for the thoughts of mortal men are
fearful, and our counsels uncertain." Therefore it is necessary that
we be directed and protected by God who knows all and can do
all things, which aid is not added to each and every act leading to
salvation, but consists in divine instincts by which the mind is
illustrated according to inborn needs and the various opportunities
or circumstances. 18 '
The fifth article 135 is closely connected with this doctrine
and might be said to be, next to the first, the most important
article in the whole question. We have seen that the gift of
q.nderstanding is an habitual disposition to receive the illumination of the Holy Ghost; that it is an aid to faith, giving negative
evidence about the primary object and positive perfect evidence
about secondary objects; that it extends its light to the principles of the moral sphere; that it is in all those in sanctifying
grace; and now we have indicated the most profound and
essential quality of the gift, its proper act in the strictest sense,
which distinguishes it from all other illuminations, inspirations
and instincts of the Holy Ghost.
Unless the human intellect be moved to this that it have a right
estimation of the end, it has not yet received the gift of understanding however much of the preambles it may know from the
illumination of the Holy Ghost. 186
Summa Theol., 11-11, q. 8, a. 4, ad Sum.
Billot, op. cit., p. 177.
185 Summa Theol., 11-11, q. 8, a. 5.

188
134

186Jbid.

6

258

JOSEPH

IGNATIUS

MCGUINESS

Because of the pecularity of faith that makes it independent
of charity and grace to the extent that it can be present without
them, though in an imperfect manner, 137 the question naturally
arises whether the gift of understanding can remain without
them too. Since its object, the propositions of faith, remains
in the graceless soul, why cannot the gift remain too. Just
because all who have grace have the gift, it does not follow
precisely that aU who have the gift have grace.
The principle which is used to establish the negative answer
is the one we have just quoted, that is, unless man have a right
estimation of his end, he has not the gift, nor sanctifying grace
either; therefore without grace there is no gift. The argument is
somewhat involved, and the conclusion is the result of two
different sets of reasoning.
It is the office of the gift to perfect the soul by rendering it
well disposed and easily moveable under the motions of the
Holy Spirit; the light of grace which renders the soul movable
to know is called the gift of understanding. But when this
potentiality to motion is actually moved, just any motion is not
sufficient; it must have a particular term to which it is directed.
Its final cause is the apprehension of truth; its efficient cause,
the Holy Ghost, moves it according to its formal cause, illumination, towards a term which will best serve grace and charity
and perfect the soul, and this term is a right apprehension of
truth which results in a right estimation of the end, i. e.,
beatitude with God. It is only a notion which proceeds according to all these causes that can be properly called the
operation of the gift of understanding. A right estimation,
therefore, is that to which the Holy Ghost most properly moves
us in this gift.
The perfection of the soul is also the work of sanctifying
grace, inasmuch as grace places man in an order in which he can
attain the end in which his ultimate perfection consists, the
vision of God. In the natural order, our faculties are only
proportionable to our last end, but by grace they are propor1 "7

Cone. Trid., sess. 6, can. 28.

THE NATURE OF THE GIFT OF UNDERSTANDING

259

tioned to it. Grace so perfects man that while he has it he
cannot err concerning his true end; he always has a right
estimation of it. Once he errs, he loses grace, and so this right
estimation is only in those who are in grace. St. Thomas, joining
these ideas by means of this right estimation of the end which
both demand, shows that without sanctifying grace, the gift is
lacking.
The objections m contain applications of the distinctive
note of understanding found in the article. The nature of the
specific action of the Holy Ghost in this gift leads almost
inevitably to a comparison of the illumination which is the gift
of understanding and the illumination which is prophecy. St.
Thomas declares briefly that the illumination in prophecy is
directed to the matters which were revealed to the prophet,
while in the gift of understanding it is directed to a right
estimation of the end. Prophecy is not a habit, but a light
given in a transient manner to the prophet who acts on principles he does not see and, therefore, he does not need a firm and
permanent habit to grasp them. He intends to form a vision
either intellectual or imaginary, with certitude, although he has
not in himself as clearly seen, the principle whence these visions
are derived. Therefore it is :fitting that there be communicated
to him from the outside a light by which the things he is to
prophesy are manifested outside their principle. 189
The gift, however, and the motion of the Holy Ghost are
not given to form some vision whether intellectual or imaginary
about the things of faith, but to apprehend and to judge of the
credibility and convenience of propositions which are in us
habitually through faith. We know that these mysteries are
worthy of belief and that any reason for denying them is
erroneous, according to the right estimation of our end to which
the Holy Ghost moves us. Prophecy is not regulated by faith
and is found in infidels and those not in grace; 140 the gift is
regulated by principles known under faith, although excited,
188
18

Summa Theol., II-II, q. 8, a. 5, ad Sum.

° Cf. John of St. Thomas, op. cit., disp. XVIII, a. 2.

100

Summa Theol., II-II, q. 172, a. 4.

JOSEPH IGNATIUS

MCGUINESS

known, and disposed by a special instinct, and is necessary to
salvation; therefore it is habitually and permanently given,
just as is faith and charity.
In the answer to the third objection, 141 we have the final
word on the distinction between faith and the gift of understanding. To faith it pertains to assent solely to principles, to
the gift to penetrate them. This is most formal in the two,
because pure and precise assent without any discussion, or
investigation, or understanding of the intrinsic notes of the
object pertains to faith. All the interior things of the object
remain so hidden to it that only by reason of extrinsic testimony
does it adhere or assent to the proposition of truth, and so it
rests in assent. The gift tries to enter into, to penetrate to
the interior of a thing, as when the Blessed Virgin asked the
angel, " How shall this thing be ? " 142 There is no hestitation
or doubt here, but the gift is striving for a fuller interior knowledge of mystery, to the extent possible in this life. Therefore,
since they proceed from distinct motives and formal reasons,
there are distinct habits of faith and understanding.
V. THE EssENCE OF THE GIFT OF UNDERSTANDING
The phrase right estimation in all this discussion is liable to
confuse a casual reader. In the first place, estimation implies
not only judgment, but also a series of judgments wherein one
thing is weighed against another, prices compared and finally
a price put upon something; for example, it is the essence of
charity to estimate its object as of great price. 143 We have
denied any sort of judgment to the gift beyond a simple assent
to truth. How then is this estimation attained ? Here is the
whole point of not only the gift of understanding but of the
other gifts as well. The man in whom the gifts are operating
acts upon knowledge that is not attained by study, or by
reasoning, or by any human operation. It is knowledge due
141

Ibid., II-II, q. 8, a. 5, ad Sum.

1 ..

Luke, i, 84.

tu Summa Theol., I-II, q.

a. 8.

THE NATURE OF THE GIFT OF UNDERSTANDING

261

entirely to the Holy Ghost who moves man to attain this true
estimate of his end with the simplicity with which natural
reason attains first principles. Man is moved to apprehend the
truth concerning his end; he sees the terms in which it is
expressed.
It is one thing to say that one cannot have a right estimation
without the gift of understanding and another to say that one
cannot have the gift of understanding without right estimation.
The first statement places the gift as a necessary companion
of right estimation, even though it does not immediately appear
that the gift is the sole cause of the right estimation, unless by
further explanation. The second statement places the estimation before the gift, as if to say that the gift is the result of
the estimation. Many have so interpreted the way St. Thomas
expresses their relation. But there is no more necessary connection between understanding and estimation in the second
statement than there is in the first. The words only say that
in any subject where the gift is found there will also be a right
estimation. The connection between them is not therein expressed. St. Thomas does however give an explanation further
on. The motion of the Holy Ghost aids man to apprehend
the truth about his end. Therefore, unless the mind be so
illumined in apprehending truth that, as a result, it is moved
to have a right estimation of the end, it is not precisely the
gift of understanding. In other words, understanding, whenever
present, produces this effect, right estimation, as well as others
like the clear knowledge of particular truths.
It is by accepting the statement, " no gift without right
estimation," to mean that the estimation is the cause of the gift,
and by joining it with the close relationship to charity that
many theologians explain the act of the gift. Vallgornera,
for instance, says:
The gift of understanding does not sharpen nor perfect the mind
as a result of study and disputation, and, as it were, metaphysically,
but from a certain connaturality and union with divine things
through charity. There are two ways we can have a knowledge
of and judge of a thing; one way through investigation and study,

JOSEPH IGNATIUS

MCGUINESS

the other through experience and a connaturality with it. Just as
a philosopher judges of charity in one way from his study of ethics
and a discussion of the virtues, while a temperate man judges otherwise, that is from its connaturality to his continence and chastity,
in like manner we can have a knowledge and judgment of supernatural and spiritual things either from study and discussion about
those things, namely the precise illustration of the truth, or from a
certain connaturality and affection, or experience of divine things,
as Dionysius said of Hierotheus that he was not only learning but
experiencing divine things. One experiences divine things when his
affection is moved by the Holy Ghost in such a way that is above
that which human modes and rules can measure; for the fact that
someone operates from obedience and subjection to the motion of
another makes him a patient or a recipient because he is obedient
and subject. This is the doctrine of St. Thomas when he says that
unless the human intellect be moved by the Holy Ghost to this,
that it have a right estimation of the end, it has not yet acquired
the gift of understanding, however much it understands the preambles to the faith from the illumination of the Holy Spirit.
(Summa Theol., II-II, q. 8, a. 5.). Only the one who does not err
about the end has a right estimation of it; he clings to it as the best
possible good. This estimation is in only those having sanctifying
grace, just as in moral matters a man has a right estimation of the
end through the habit of virtue. Therefore the gifts which pertain
to the intellect perfect it mystically, that is, affectively and by
reason of a certain experimental knowledge and judgment of divine
things; this experimental knowledge cannot stand without affection
and taste by which divine things are united to us and quasiconnaturalized. The reason is that we cannot philosophize about
these gifts except as is given in Scripture, which founds these gifts
in some sort of affection and taste, as "Taste and see." (Ps.,
xxxiii, 9); "A new name written, which no man knoweth but he
that receiveth it." (Apoc., ii, 17); "A good to all that do it." (Ps.,
ex, 10); and" ... the spirit of the Lord will rest upon him." (Is.,
xi, 2) . Therefore these cognitions, those of the gifts, are founded
in the spirit of affection, not in any way whatever, but resting
upon and united with us .... 144

This is the substance of all that John of St. Thomas says
with much more fire and rhetoric, and following him, most of
1u Vallgornera, op. cit., n. 560.

THE NATURE OF THE GIFT OF UNDERSTANDING

the French theologians,
Thomas says,

especially

Gardeil. 145

268

John of St.

Faith alone and naked leaves us in obscurity, and men therefore
become bored and cannot persevere in contemplation of faith alone;
they wander, they fall asleep, are bored because faith alone does
not contemplate but blindly assents, and the heavens seem more
overcast than opened . . . . From this we gather that it is necessary for the soul to break forth from the foggy mist of faith, and run
to meet God through the illumination of the gifts of the Holy
Spirit by which the mind, as if in golden vestments, is girt about
with various colors, i. e., a multitude of spiritual sensations, and
multiple knowledge of divine things. But because in this life faith
cannot be illumined and shine on the part of the object, since it is
always based on testimony . . . it remains for the soul captive in
the bonds of faith to be illuminated by the flames of love. Therefore
it is fitting that the gifts of wisdom, understanding, and knowledge
proceed from love, be based on it, that they might dissolve the
mists of faith. 146
He proceeds then to apply to understanding what St. Thomas
expressly teaches of wisdom, and repeatedly says of understanding-that:
the mind is illumined about divine things according as they are
sensed within us and according to a connaturality and a certain
affective union pertaining to the experience of divine things. 147
It is a very beautiful and makes excellent reading. It is
based in part on the sound teaching of St. Thomas on the
connection of the gifts and the nature of the gift of wisdom,
but a doubt arises: is it the mind of St. Thomas on the gift
of understanding? We are reminded of a remark of Father
Ramirez," One must watch to see whether everything in John
of St. Thomas is of St. Thomas, or whether there is not also
something only of John." 148
To say that the gift of understanding penetrates divine
146 Cf. art. cit., in Diet. Theo. Catk. Also: La
de l'OifTI,e et l'expirience
mystique (Paris:. 1927)' n, 221.
1 •• John of St. Thomas, op. cit., a. 1.
101 Ibid., a. 8.
148 "i.Que es un Tomista?"
in Ciencia Tomista, XXVII (1928), 188.

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MCGUINESS

truths from a savory taste for them that is connatural seems to
contravene the Aristotelian-Thomistic principle: nothing can be
willed which is not first known. Further, it is not expressly
taught by St. Thomas; indeed, it does violence to what he
teaches not only here in the fourth and fifth articles but in the
first article and in the Sentences. Finally, not only it is unsupported by his manner of speaking-always applying light
and illumination to understanding, and to understanding alone
among the gifts-but it contradicts what he expressly said in
the Sentences.
The relation of will to intellect, of love to knowledge is one
of the corner-stones of the whole edifice of St. Thomas' teaching.
Absolutely speaking, the will is inferior to and subject to the
intellect because "the object of the intellect is the very reason
of the appetible good; appetible good whose ratio is in the
intellect, is the object of the will." 149 It is only in a particular
consideration where the object of the intellect and will is of a
higher order than they, that in willing the object the will becomes ennobled, while the intellect in knowing remains the
same, whence the love of God is better than knowledge of Himr
in this life. But the fact remains that were God not presented
to the will by the intellect as a desirable good, He would not be
loved. To say therefore that the love which already possesses
a thing moves the intellect in some way to know it, is to invert
the natural order of the two faculties. To say that we apprehend divine truths from an innate taste which comes from their
possession by love is an implausible paradox. To apprehend
something in the sense in which it is applied to the gift of
understanding is to progress from a state of privation of truth
to the state of possession. Just as no one gives what he has not,
so no one receives what he already has. If divine truth is
already present and sensed, it cannot be acquired by that sense.
It is of course quite otherwise with the gift of wisdom whose
acts are the application of knowledge already acquired to other
things. Its knowledge is affective and not acquired by any
uo Summa

Theol., I, q. S!l, a. 8.

THE NATURE OF THE GIFT OF UNDERSTANDING

265

study or reasoning, and the Holy Ghost moves it to apply this
knowledge to divine and by extension to human things.
If it is objected that faith supplies a sufficient knowledge for
charity to start, and that charity outstrips faith in attaining
union with God, whence it commands the gifts to search further,
the doctrine of the fourth article seems vitiated. The whole argument rested on the one point that because charity needed knowledge with a more perfect light than faith, the gift of understanding was infused to feed charity, not as a consequent to charity,
but in the words of St. Thomas, ". . . the will cannot be rightly
ordained to good, unless there preexist some knowledge of the
truth." The Holy Spirit " illustrates the mind to know supernatural truth to which the right will should tend." This can
hardly be interpreted to mean that the will ordains the intellect
to know the truth which it possesses.
It would denote a grave defect in the order of his work, if
St. Thomas were to treat of the formal aspect of a gift-as this
connatural taste is for John of St. Thomas- 15 not where he is
treating specifically of that gift, but thirty-five questions later,
under the heading of another gift and expressly applied to that
other gift.
1)

Wisdom denotes a certain rectitude of judgment according to the
eternal law. Now rectitude of judgment is twofold: first, on
account of perfect use of reason, secondly, on account of a certain
connaturality with the matter about which one has to judge. Thus,
about matters of chastity, a man after inquiring with his reason
forms a right judgment, if he has learnt the science of morals, while
he who has the habit of chastity judges of such matters by a kind
of connaturality.
Accordingly it belongs to the wisdom which is an intellectual
virtue to pronounce right judgment about divine things after
reason has made its inquiry, but it belongs to wisdom as a gift of the
Holy Ghost to judge aright about them on account of connaturality
with them: thus Dionysius says that Hierotheus is perfect in divine
things for he not only learns, but is patient of divine things.
Now this sympathy or connaturality for divine things is the result
of charity, which unites us to God, according to " He who is joined
160

Gardeil, La SfJructure de l'ame, II, 9!21.

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JOSEPH IGNATIUS

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to the Lord, is one spirit." (I Cor., vi, 17.) Consequently wisdom
which is the gift, has its cause in the will, which cause is charity,
but it has its essence in the intellect, whose act is to judge aright. 151
Are not these the very words which John of St. Thomas,
without any warrant, applies to the gift of understanding?
Even if this connaturality were common to both gifts, it seems
more logical to speak of it in connection with the first, and then
refer back to it, if necessary. Yet the only thing in common
which St. Thomas mentions each time in its proper order, is
charity, applying his general doctrine to each gift.
This notion of affective union is to the notion of the gift of
wisdom what the notion of light and illumination is to the gift
of understanding. In the first article of this question the general
notion of what this gift is like is laid down, and likewise in the
forty-fifth question. Then, in the second article of both questions, this general notion is developed and limited by comparing
it with the virtue to which it is attached, faith and understanding, charity and wisdom. Just as faith rules and measures the
light of understanding, so charity rules and measures wisdom
by giving it the experience for divine things through which it
judges. Is it too much to expect that if this divine experience
were also the foundation of understanding there would be some
mention of the fact, even parenthetically, in either tract? The
only mention of understanding is in one of the objections which
tries to show that wisdom is superfluous. The answer is that
they have different acts, that is, understanding perceives and
wisdom judges-again that contrast between motion toward
knowledge and motion away from knowledge already gained
and toward other things.
St. Thomas consistently speaks of wisdom as a judgment,
the application of something known to something else, but he
always speaks of understanding as a light, the Holy Spirit
illuminating the mind. Nor does he ever interchange the terms.
Now here in the tract on the gift of wisdom is there any mention
of illumination except in relation to understanding and nowhere
161

Summa Theol.• ll-ll. q. 45, a. !!.

THE NATURE OF THE GIFT OF UNDERSTANDING

267

in the tract of the gift of understanding is there a mention of
connatural experimental taste. Light, illumination, illustration,
are the terms always applied to understanding-'" supernatural
light, ... the light superadded is to supernatural things, as the
natural light to first principles." 152 " Understanding illumines
the mind concerning things learned"; 153 "so also the Holy
Ghost illumines the mind .... 154 " Intellectual light of grace is
called the gift of understanding ... not yet attained the gift,
no matter how much from the illumination of the Holy
Ghost ... ; ... it is not illustration of the mind concerning a
right estimation." 155
We have in the commentary on the Sentences certain expressions which reveal that here at least St. Thomas did not agree
that taste enters into the gift of understanding. Because of the
order of the master of the Sentences, wisdom is treated first
and is followed by understanding. Note that his doctrine on
wisdom has not been changed in the Summa.
. . . the gift of wisdom has an eminence of knowledge through a
certain union with divine things with which we are not united
except through love, as he who adheres to God is one spirit with
Him. . . . Wisdom presupposes dilection (the act of charity) as a
principle and so is in the affection, but as to its essence it is in
knowledge; whence its act here and hereafter seems to be to
contemplate divine things, and then through them to judge of
others, not only in speculative, but also in practical matters, in
which judgment is taken from the end, and therefore against
wisdom is folly which implies an error about the end. 156
Thus is, briefly and beautifully expressed, the nature of the
gift of wisdom. Now, the next question is to consider understanding, and he says, as we have seen, that it is the gift which
illumines the mind about things heard after the manner of
first principles. Then the objection is raised that wisdom experiences delight about divine things, but so does understanding; therefore they are not distinct. He answers that
Ibid., q. 8, a. 1.
Ibid., a. 2.
154 Ibid., a. 4.
162

163

Ibid., a. 5.
••• III Sent., d. XXXV, q. S, a. 2, qt. 3.

155

JOSEPH IGNATIUS

MCGUINESS

any delight in understanding is a natural one caused by the
congruity of the operation to the faculty operating; not however
from a love of those things concerning which the operation is,
as in wisdom.
His general comparison of the two is this:
Understanding names a simple apprehension; but wisdom is a sort
of fullness of certitude to judge about what is apprehended, and
therefore understanding pertains to the way of invention and
wisdom to the way of judgment. But because judgment cannot be
concerning things apprehended except through supreme causes, to
which the wise man is united in mind, which union to divine things
is through love; therefore, wisdom is principally concerned with
divine things and has in them a delight caused by dilection.
Understanding on the other hand is indifferent concerning all apprehended spiritual things, and in itself it implies, no delight from
the love of the things apprehended. 157
For St. Thomas, then, however much the gift of wisdom may
involve an experimental taste of the divine, the gift of understanding has none of it, except perhaps as a secondary effect of
its operation. Understanding is, rather, a disposition by which
man, under the illumination of the Holy Ghost, penetrates the
propositions of faith and judges of their truth.
It is interesting to note what St. Albert taught on this matter
of the essential characteristic of understanding. Even though
he was St. Thomas' best loved teacher, it would be folly to
argue that since he taught Thomas and his doctrine is thus
and so, therefore it is that of St. Thomas too. We know of too
many divergencies in their thought to permit so groundless an
argument. In this case, St. Thomas seems to agree with the
simple forceful language of his saintly master. St. Albert, after
exposing the nature of the gifts, raises the objection that on
the authority of St. Augustine it seems that the office of the
gift is to know God and to love and embrace Him, and therefore it is no different from wisdom. The answer is that
although it has charity as a mover inasmuch as charity is the
general mover in every good, nevertheless, it differs from wisdom,
167

Ibid.

THE NATURE OF THE GIFT OF UNDERSTANDING

269

because wisdom is in the taste (gustus) of goodness, as is often said,
but understanding is in the contemplation of truth alone. 158

In his Compendium of Theology, he says,
Wisdom and understanding differ because . . . by understanding
God is known through illumination of things heard in Holy Scripture; by wisdom He is known by experiment. Likewise, through
understanding we know God; by wisdom we taste his sweetness ... 1119

The two great masters then, are agreed on this, at least, that
the knowledge of the gift of understanding is not affective but
directly caused by the illumination of the Holy Ghost.

VI. UNDERSTANDING

DISTINCT FROM OTHER GIFTS

Enough has been said about the objects and acts of the gift
of understanding to permit a discussion of its distinction from
the other gifts of the Holy Ghost. Briefly the gifts are seven in
number: wisdom, a right judgment of divine things according
to a certain connaturality with them; 160 understanding, a penetration and a grasp of the things to be believed; 161 knowledge,
a certain judgment about revealed truths; 162 counsel, the immediate direction of God about those acts which lead to salvation; 168 fortitude, a firmness to overcome all obstacles and
dangers in finishing the work we have begun; 164 piety, the filial
affection for God; 165 and fear of the Lord, a reverence and
subjection to God. 166 These are the seven habits which perfect
all the faculties of the soul by making them sensitive and docile
to the special inspirations of the Holy Ghost. Let us recall what
was said in the introduction about St. Thomas' norms for
distinguishing habits. There are three ways: by their active
Ill Sent., d. XXXV, a. 10, ad 4um. Opera Omnia, XXVIII, 656.
Compendium Theologicae Veritatis, lib. V, c. 46. This work has been attributed
to Hugh of Strassburg, a disciple of Albert.
160 Summa Theol., 11-II, q. 45, aa. 3 and 4.
'"'Ibid., q. 8, a. 2, Sed Contra; a. 6.
'"'Ibid., q. 139, a. 1.
165 Ibid., q. U1, a. I.
••• Ibid., q. 9, a. 1.
100 Ibid., q. 19, a. 9.
163 Ibid., q. 52, a. 1.
158

169

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JOSEPH IGNATIUS

MCGUINESS

principles, by the subjects of inherence, and by their formal
objects. 167
Now, obviously, the active principle is the same in all the
gifts-the Holy Ghost. So, only the two remaining ways will
avail us here. St. Thomas proceeds to apply the second rule and
so separates understanding from fortitude, piety, and fear of
the Lord, because they by definition pertain to the appetitive
faculties of our nature. In view of the difficulty to come, he
cannot resist a human remark. This is manifest, says he, " but
the difference of this gift from the other three which perfect the
cognoscitive power is not so manifest." 168
There were some who sought to further distinguish the intellectual gifts according as they perfected the speculative or the
practical part of man's intellect, and among them, St. Thomas
himself was to be found for a time. 1il 9 But, meditation on the
extensive part that faith plays in our lives led him to change his
teaching so as to permit understanding to be practical 170 in a
sense, and knowledge to be speculative. 171
The basis then for the correct distinction of the intellectual
gifts, will be, not their subject, but their formal objects which
are found in the supernatural knowledge of faith. Faith is, after
all, the ordinary means of knowing God in this life. Special
revelations and divine touches are not for all, but only for
those whom God chooses to lead in this extraordinary way. The
gifts are common to all the just, and so according as they assist
and perfect different aspects of faith will the gifts be distinguished.
St. Thomas recapitulates the essentials of faith: that it is an
assent to things not seen, but heard; 172 that it is principally
concerned with God as first Truth; 173 secondarily with certain
creatures; 174 and finally, that it extends to the direction of
human works 175 according to the Apostle's " Faith worketh by
charity." 176
Ibid., I-II, q. 54, a.
q. 18, a.
Ibid., II-II. q. 8, a. 5.
169 Ibid., I-II, q. 68, a. 4.
170 Ibid., II-II,
q. 8, a. 8.
171 Ibid., q. 9, a. 8.

Ibid., q. 1, a. 4.
Ibid., a. 1.
1 .. Ibid.
175 Ibid., q. 4, a.
ad Sum.
176 Gal., v, 6.

167

1 ..

168

178

THE NATURE OF THE GIFT OF UNDERSTANDING

271

On the part of the things proposed to faith for belief, two things
are required from us; :first, that these things be penetrated or
grasped by the intellect, and this pertains to the gift of understanding; secondly, it is necessary that man should judge these
things aright, that he should consider these things to be embraced
and their opposites avoided. This judgment, when it concerns
divine things, belongs to the gift of wisdom; if concerned with
created things, it pertains to the gift of knowledge; :finally,if applied
to individual actions, it comes under the gift of counsel.177
Therefore to each essential point of faith, there is attached a
special gift.
Had we not noted and discussed them, the problems raised
by having understanding direct human affairs and produce a
right estimation would make the distinction of the gifts here
not so manifest. But, to repeat, understanding extends only
secondarily to human affairs, inasmuch as it furnishes a grasp
of the supernatural principles and laws governing them, the
actual regulation of which is left to wisdom and counsel. Understanding produces a right estimation, as Cajetan says:
because this estimation, and any other judgment, as regards perception, looks to the gift of understanding; as regards judgment it
looks to wisdom or knowledge or counsel, just as assent looks to
faith. 178
In the answer to the first objection, St. Thomas gives another
way of distinguishing the gifts among themselves which was
very common in his time-according to the vices which they
opposed. This is the method of St. Gregory, and after him of
some of the early Scholastics. The vice which is opposed to
understanding is dullness, the opposite of sharpness. An intellect
is said to be sharp when it is able to penetrate to the heart of
things proposed to it. This is another similitude drawn from the
sensible order. The eye is said to be sharp when it sees its
object at a distance or is able to penetrate the smallest details.
So it is with the intellect. Its object is, in a way, distant from it;
it must know essences· through the medium of properties, and
causes through their effects.
177

Summa Tkeol., 11-11, q. 8, a. 6.

••• Comm. in II-II, q. 8, a. 6.

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Consequently, a man is said to have an acute sense in connection
with his understanding if, as soon as he apprehends a property or
effect of a thing, he understands the nature of the thing itself, and
if he can succeed in perceiving its slightest details; whereas a man
is said to have a dull sense ... if he cannot arrive at knowing
the truth about a thing without many explanations; in which case,
he is unable to obtain a perfect perception of everything pertaining
to thct nature of that thing. 179
Folly is a perverse judgment about the common goal of life,
and is opposed to wisdom. Ignorance is a particular defect, and
is opposed to knowledge. Precipitancy is action without sufficient deliberation, and is opposed to counsel. Here we have the
natures of the various gifts well marked out by contrast, and
the penetration of understanding emphasized.
A difficulty crops up again concerning faith. In the natural
order, the one habit of intellect suffices to apprehend first
principles and to assent to them, therefore in the supernatural
order, since the articles of faith are its first principles no faith
alone is sufficient to penetrate and assent, and therefore the
-habit is superfluous. We deny the parity. The habit of intellect
is a perfect participation of the natural iight of reason, and is
able to do both, but faith is an imperfect participation of divine
light, and cannot do both without divine aid. 181 It belongs to
faith to assent to that knowledge conferred by grace, but it
belongs to understanding to pierce in a supra-human way, the
things that are to be believed.
If the gift of understanding is both speculative and practical,
it seems common to all the gifts, and therefore is not really
distinct from them. The answer is that, while it is related to
both speculative and practical knowledge, it formally looks to
apprehension in them and not to judgment. But, we have already said that there is also a judgment in understanding, and
so the difficulty stands. The judgment in understanding, however, is a discerning judgment which penetrates truth by separating it from error and falsehood, but the judgment in the
100

Summa Theol., II-11, q. 15, a. 2.

Ibid., q. I, a. 7.
181 Cf. Sylvius, Oo:mm. in 11-11, q. 8.

180

THE NATURE OF THE GIFT OF UNDERSTANDING

other gifts is an analytic sort of thing resolving things by their
causes, and it is this analytic judgment that St. Thomas denies
to understanding.
In judging things, we can proceed in two ways; first, by a
resolutive or analytic judgment, when we judge of things
through their causes or their effects, by resolving and reasoning
upon them; the other way, by a simple discretive judgment, by
which we judge that this is not that, or is not as that is, but
has a different relation to that, which can be done through some
comparison or reflection as does the intellect, or in a simple way
as the senses, discern sounds and colors, etc. The gift of wisdom
has a judgment concerning spiritual and supernatural things in
a resolutive and analytical fashion through their highest causes,
i.e., through an intimate union with God; knowledge, moreover,
through inferior causes or effects, inasmuch as it considers
creatures-faith judges an assent neither through causes or
effects, but from the naked testimony of the teller.
The gift of understanding judges neither by resolving nor by
reasoning about supernatural truths from causes and by causes,
but from a certain illumination of the Holy Spirit it discerns
spiritual from corporeal things, at least in a negative way, and
it separates from error things to be believed as true. For this
judgment the evidence of argument is not required, because it
does not proceed through causes or effects;. nor is there required
a resolution of conclusions into their principles, because the gift
like the habit of first principles is concerned with principles. It
forms this judgment from the better and more acute penetration of the terms from which these truths are composed and
their convenience among themselves and the inconvenience of
errors. In natural things there are certain principles known to
all and others known only to the wise because their terms are
not easily penetrated by all, but only by the more acute, as,
e. g., that spiritual substances are not in place, and that there
are not many gods, because the perception and penetration of
these terms depends on a comparison and collation with their
opposites. Yet, nevertheless, the judgment of these principles
is not made through collation and arguments, but from a pene7

JOSEPH IGNATIUS

MCGUINESS

tration of the terms brought about by comparison and collation.
In like manner, by the impulse and illustration of the Holy
Spirit the gift sharpens and elevates the mind to seize and
penetrate the terms by which supernatural truths of faith are
proposed, and from such penetration judges those truths to be
believed, and rests in them.
To the objection which is made from the words of St.
Thomas 182 according to which wisdom and knowledge exclude
argument, and therefore the gift of understanding cannot differ
from them according as it is discretive and they discursive, John
of St. Thomas replies,
Admitted that the gifts of wisdom and knowledge are not discursive, there remains a djfl'erence between wisdom and understanding, because understanding is discursive neither on the part of
the thing known nor on the part of the way of knowing, i. e., the
knower, because it proceeds about principles by penetrating and apprehending them from a knowledge of the terms, and so the things
known are not subject to argument, from the manner of knowledge
it does not proceed fu a resolving manner, but by a simple judgment
apprehends the truth. But wisdom.and knowledge proceed in aresolving manner at least on the part of the things known, because they
proceed from causes, giving an account of the truth they know;
although on the part of the knower they proceed without arguments-just as the angels have resolutive knowledge, inasmuch as
on the part of the object they know things through their causes,
although on the part of the knower they do not form arguments
from many acts but by one act know cause and e:ffect.188

So, the gift of understanding remains distinct from all the
others because it apprehends, grasps, and judges of divine
truths, after the manner of first
Speaking of the vices opposed to the gift/ 84 St. Thomas also
mentions blindness of mind, and indicates there the dispositions
and, indirectly, the circumstances which are most propitious for
the operation of this gift. Blindness of mind is a privation of
the principle of intellectual vision which is threefold: the light
Summa Tkeol., 11-11, q. 8, a. I, ad lum.
John of St. Thomas, op. cit., dis. XVIII, a. 4.
1 "' Summa Tkeol., 11-11, q. 15.

18 "

188

THE NATURE OF THE GIFT OF UNDERSTANDING

275

of reason, the light of grace, and intelligible princples through
which a man understands other things. The first is never forfeited by the soul; the second is, sometimes, but its privation
is a punishment rather than a sin; it is in the loss of the third
that sin enters. Blindness of mind is opposed to the gift, and
St. Thomas asked if is it a sin. This is the answer:
That man does not attend to an intelligible principle whence other
things are known happens in two ways. Sometimes it is due to the
fact that a man's will is deliberately turned away from the consideration of that principle ... whereas sometimes it is due to
the mind being more busy about things which it loves more, so as
to be hindered thereby from considering this principle. In either
of these ways, blindness of mind is a sin. 185

In a further article, he shows how this vice, and that of dullness, arises from carnal sins of lust and gluttony. 186 Hence, the
dispositions for the operation of this gift on the part of man are
abstinence and, above all, chastity. Further, from his consideration of conversion and aversion of the mind to some intelligible
principle-some article of faith perhaps-it is evident that without such conversion, the Holy Ghost will not activate the gift.
He accommodates Himself to the order of nature, and takes
occasion to act in us from some external circumstances which
turn our thoughts to things of God, from the reasonings we
form in meditation, from hearing the word of God preached,
from spiritual reading, from all actions which affect us well or
ill, and above all in prayer .187

VII. THE GIFT IN HEAVEN
One question remains to be considered before we can apply
ourselves to summarizing St. Thomas' doctrine on the essential
nature of the gift of understanding. He does not consider it
here expressly, but the principles of a satisfactory solution can
be gathered from other places in his writings. The question as
already stated is what act, if any, does the gift exercise in
heaven where it is found without faith.
185

Ibid., a. 1.

186

Ibid., a. 8.

167

Billot, op. cit., p. 188.

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MCGUINESS

St. Thomas seems to teach that the gift of understanding
becomes the light of glory, because he attributes the perfect
vision of God in heaven to the gift.
Vision is twofold: one is perfect whereby God's essence is seen; the
other imperfect. . . . Each of these visions of God pertains to
the gift of understanding; the first to the gift in its state of perfection as possessed in heaven, the second to the gift in its beginnings
as it is possesssed by wayfarers. 188
He expressly speaks of vision whereby we see the essence of
God as pertaining to the gift, but only the light of glory can
elicit the vision of God; therefore the gift and the light of glory
seem to be the same. Again he says:
the gift of understanding whose office it is to apprehend spiritual
things in heaven, stretches to the essence of God, by intuiting
Him.lsa
Is it not the light of glory which alone touches the essence of
God by intuiting Him?
Those gifts which have an object which in common with a virtue
will remain in heaven will not remain distinct from those virtues
from which they are distinguished only in imperfection and perfection of mode of operation, as is evident in faith and understanding,
because the vision which succeeds faith pertains to the perfect
gift.1'90
In other words, the gift in heaven is no different from the habit
which effects the divine union, i. e., the light of glory.
In spite of all this, we must say that in heaven the gift
remains distinct from the light of glory, although it is regulated
by it and the beatific vision. In this life, as we have seen, the
gift is regulated and measured by faith, because by faith we are
joined to truth, moved to believe by divine testimony, and
illumined by the Holy Ghost to penetrate what we believe and
to discern it from error. In heaven vision succeeds faith and
therefore the gift will then be regulated by vision. In this life,
understanding does not elicit the act of belief; in the next it
will not elicit the vision. It presupposes the mind united to
Summa Theol., II-II, q. 8, a. 7.
III Sent., d. XXXIV, q. 1, a. 4.
190 Ibid .• d. XXXII, q. 1, a. 8, ad 6um.
188

189

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277

God in some way, that the Holy Ghost may find it docile to be
moved to understand the mysteries concerning Him.
The gifts are compared to the theological virtues through which
man is united to the Holy Spirit who moves him (in the gifts)
as the moral virtues are compared to the intellectual virtues through
which is perfected reason, the mover in morals.191
The gift, in its formal aspect, abstracts from faith or vision;
it remains a disposition to be moved by the Holy Ghost to
penetrate truth.
St. Thomas has a special article on whether the gifts will
remain in heaven/u 2 and answers that according to their essence
they will be most perfect in heaven, because they perfect the
mind to follow the instincts of the Holy Ghost, and in heaven
man will be totally subject to God. Hence in heaven the gift
will be regulated by the Vision. According to the matters in
which they operated, they will not be found in heaven. Answering an objection, he remarks that the illumination of the mind
will remain as the gift of understanding. However, the vision of
God is not that by which we follow the instincts of the Holy
Ghost, but rather that by which we possess, and are united to,
Him. Therefore the gift and the light of glory are distinct.
Moreover, in Christ we find all the gifts, and the light of
glory as well, and so, obviously, the light of glory and the gift
are distinct. It cannot be objected that the gift and the light
of glory are distinct in Christ only because he was at the same
time wayfarer and comprehender, but in ordinary wayfarers
there are seven gifts and in comprehenders the light of understanding becomes the light of glory. The gift of understanding
was either an obscure light repugnant to one in glory, or an
evident and clear light. If obscure, it could not be found in
Christ, as neither faith nor any imperfection in knowledge can
be ascribed to Him. If clear and evident, there is no reason why
the gift could not remain even after He ceased to be a wayfarer
just as His infused knowledge remains, because it is perfect in
itself and not repugnant to the light of glory.
191

Summa Theol., I-11, q. 68, a. 8.

,.•• Ibid., a. 6.

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As for the expressions cited by some from St. Thomas, to
show that the light of understanding becomes the light of glory,
we understand them in the light of what St. Thomas has taught
on the subjection of the gifts to the theological virtues. The
perfect vision of God's essence belongs to the gift, not that the
operation of the gift is the cause of the vision, but inasmuch as,
after the vision is obtained, the gift can operate in all its
perfection, no longer hindered by faith, but now regulated only
by the clear vision of Infinite Truth which succeeded faith. The
other two texts are to be understood in the same way, not
formally but as consequences of the very vision itself. For St.
Thomas says:
The gifts which perfect us ill the contemplative life, [wisdom and
understanding] will remain as to the acts which they had about
their proper matter, but they will be perfected as to their mode,
because no matter how much they were elevated in this life, they
could not attain the heavenly mode. 193
So, just as with the gift of understanding, the Holy Ghost
moves us to penetrate the mysteries of faith in an imperfect
manner in this life, so in the contemplation of the essences of
God as He is, the Holy Ghost will move us to see at last
perfectly those things which escaped us here. " Now this is
eternal life, that they may know Thee, the only true God." 194
Conclusion: The gift of understanding is a habit which
renders us prompt to follow the impulse of the Holy Ghost.
It is found in all who are in the state of sanctifying grace, and
in them only. The essential notion of this gift is that in it the
Holy Ghost illumines us by his light to penetrate and to judge
with a simple assent the primary objects of faith imperfectly,
the secondary object perfectly; not by any connatural taste but
by directly strengthening our intellectual light; and by this it
is distinguished from all other gifts.
JosEPH IGNATIUS McGUINESS,

Dominican House of Studies,
W askington, D. C.
198

III Sent., d. XXXIV, q. I, a. 8.

:1.u

John, xvii, 8.

O.P.

SOLUTION OF THE PROBLEM OF SPECIES *
I.

INTRODUCTION

1. In the opening pages of Problems for Thomists: The Problem
of Species/ I distinguished two senses in which philosophers use the
word "problem": either "to signify an open question, an issue or
dilemma not yet demonstratively resolved," or " to mean a question
to which several contrary answers have been given, among which we
are able to discriminate the true from the false." 2 Strictly speaking,
the latter is a solved problem, and as solved it is no longer a problem
for purely philosophical inquiry. It may, however, remain a problem
for the philosopher in his role as historian of thought. There is both
philosophical and historical interest in trying to account for the
origin and persistence of theories we know to be false. But in the
case of the unsolved problem, the primary aim is philosophical: it is
to resolve an issue constituted by conflicting theories, each of which
is possible, and neither of which is known to be true.
I proposed the problem of species as a problem for philosophical
inquiry because I thought I had found an unresolved opposition
between two theories about the number and order of species, as
discussed in the philosophy of nature. Let me
these matters
report at once the formulation which I made of this issue. With
respect to the number of species (the number of specific distinctions
among corporeal substances), the issue was between a first theory
which supposed a small and definitely known number (more than
three and less than ten), and a second theory which supposed a
larger and not definitely known number. With respect to the order
of species, the issue was between a first theory which affirmed a
perfect hierarchical ordering but denied, in doing so, the presence in
two proximately related specific natures of a common generic element; and a second theory ·which denied a perfect hierarchical
ordering but affirmed the presence of a common generic nature in
diverse species. 8
*An analytical outline of this article will be found on pages 878-9.
For brevity, I shall hereafter refer to the book as The Problem of Species. I
shall also have to assume that the reader of this article is somewhat familiar with
matters under discussion in the book (New York, 1940), or in the series of articles
published in THE THOMIST (Vol. I, Nos. 1, 2, 8; Vol. II, Nos. 1, 2) .
• Op. cit., p. 1; THE THOMIST, I, 80.
• This summary of the issue is, of course, too brief to be adequate. For a full
summary, vd. op. cit., Chap. VI; THE THOl\U:ST, I, 481 ff. It must suffice here to
point out that there is a connection between what each theory holds about the
1

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MORTIMER J. ADLER

The problem which I proposed as philosophical no longer seems
to me to be a problem of that sort, because I now think that the
issue between the two theories can be completely resolved. To state
my present view more accurately, I should say that the questions
about the number and order of specific natures can be demonstratively answered. This is more accurate because the issue cannot be
resolved in favor of either theory as previously formulated. I might
describe the situation as I now see it in either of two ways: (I) by
saying that there is a third theory which is able to combine the
truths contained in the first and the second theory a,nd, at the same
time, excludes their errors-a sort of Hegelian synthesis of the halftruths contained in thesis and antithesis; (2) by saying that the
first theory contained an accidental error, the rectification of which
permits it to be proved, whereas the second theory is essentially
erroneous and can, therefore, be completely disproved. Only the
second of these two statements is really accurate, and therefore I
must describe the situation in that way. The reader will see this to
be the case when, later, he sees that the error made in the formulation of the first position is appropriate, but not essential, to its
disagreement with the second position, so that when the first position is rectified by the removal of this error, it still differs from
the second position on critical grounds. In contrast, the error
in the second position is essential to its disagreement with the
first position; hence, should that error be removed, the second position would be reduced to the first, in which case, of course, the
problem would be solved, for there would no longer be an opposition
of conflicting theories, but only one true account of the matters
under consideration. 4
number of species and how it views their order. This is made plain in the exposition of the two theories in Chapters IV and V respectively. One other point needs
to be made explicit: the second theory does not deny hierarchy in every sense, but
only that perfect hierarchical order in which each member is specifically distinct
from its proximate inferior or superior; thus, if oyster and cow are species of a
generic brute nature, and along with other species of brute differ generically from
man, the hierarchy of species is imperfect, even if all the species of brute are perfectly ordered inter se, for the highest of the infra-human animals would not differ
specifically from man, but only generically.
For brevity, I shall hereafter refer to the " first theory" and the " second
theory," or the " first position" and the " second position," assuming that the
reader will remember the essential points of opposition thus being indicated.
•1n the book I considered the possibility of a third theory, combining the answer
given by the first theory with regard to the ordering of specific natures, with the
answer given by the second theory with respect to their number. Vd. fn. 167, p.
142; THE THOMIST, I, 440, fn. 167. But I now see that a third theory, so conceived, is impossible. The number of species which can be affirmed is limited by
the principle of a perfect hierarchical ordering, which is the chief principle of the
first theory.

SOLUTION OF THE PROBLEM OF SPECIES

fl81

It is also true to say that the issue, as I stated it, between the
first theory unrectified and the second theory is a false issue. It is
not surprising, therefore, that this false issue should have appeared
to be irresolvable. It was ir.resolvable because it was false. If a man
propounds a false problem, he cannot hope to solve it. It does not
follow, of course, that every true issue is resolvable, for there may
be some genuine problems which we cannot solve. But, fortunately
for the philosophy of nature, the problem of species does not belong
with the mysteries. When the true issue is stated, as between the
second theory and the first theory rectified, that issue can be completely resolved in favor of the correctly formulated first position.
Though the issue between the rectified first theory and the erroneous second is a true issue, in the sense that there is always an issue
between truth and error, the problem of species is no longer a
genuine problem for the philosopher of nature as such. All that
remains of the problem now belongs to historical research in philosophy, for it is still worth while to explain, if we can, the origin and
persistence of the false notions constituting the second position.
Such historical explanations have philosophical value in so far as
they help the philosopher to understand the truth better by knowing the causes of error.

2. It is not often that one achieves a clarification of intellectual
difficulties so speedily and so completely. In so far as, in formulating
the first position, I made the error which generated a false issue, I
am, of course, responsible for some of those difficulties; but may I
say, in partial extenuation, that I made this error in the course of
working toward a true issue? H I had not been working in this
direction, I might not have made the error; but then I also might
not have discovered the true theory, made evident by a demonstrative resolution of the true issue. In short, there are real difficulties,
not of my making, in the second theory of species-a theory of
ancient origin, as well as currently prevalent. In one sense, there
was no problem for Thomists in these questions about the number
and order of species, because the true answers to these questions
constitute a thoroughly Thomistic theory; but, until the true
answers be demonstrated and the errors in the second position
uncovered, there was and is a problem here for any Thomist who
adheres to the second theory, because the difficulties intrinsic to
that theory arise from its conflict with fundamental Thomistic
truths.
I can take the blame for having made an error, but I cannot take
credit for its discovery. I owe, and wish to record, a debt of gratitude to those critics who, through really trying to understand the

MORTIMER J. ADLER

problem as I saw it, helped me to discover the error, thus enabling
me to correct it and to reach the clarification and solution I am
now about to present. Viewed objectively, it would have been
better not to have made an error, but viewed subjectively, making
this error became the occasion for a surer realization of the truth of
the first position. And this course of events may be fruitful, not only
for me, but for others who will learn from this adventure in thinking
and discovery something about the constraining and regulative
beneficence of basic Thomistic principles. There is no better sign of
the objectivity of truth in a philosophy than the common obligations it imposes upon everyone who works under its aegis.e
3. Let me name the error at once. It consisted in denying a
common generic element in two specific natures, proximately related as higher and lower; it consisted, furthermore, in regarding
this denial as essential to the principle of a perfect hierarchical
ordering of specific natures. As I originally formulated it, the first
position contained this error. This error was called to my attention
by the critic who asked how animal could be predicated of both man
and brute, or of both man and cow. If I tried to answer this question
in a manner quite consistent with my erroneous formulation of the
first position, I would have to say that animal is predicated of man
as genus, and of cow as species, for according to the first position,
as unrectified, the sensitive nature, which is the generic element in
human nature, is indifferently conceived by animal or brute; and
since cow is merely a race or sub-species (an accidental concretion,
not an essence) of brute, animal or brute, indifferently, signifies
the whole specific nature of cow. My critic could then reply that if
this account of the predication of animal be essential to the first
position, then that position must be essentially erroneous, because
it is impossible for one concept to be predicated of two others, both
its inferiors, in the one case as genus, and in the other as species.6
• If I had not violated a Thomistic principle, I would not have made the error
which prevented me from seeing the unblemished truth at once. Since I made the
error willingly, I
at fault, even though I may try to excuse the willful blindness by the excessive zeal with which I tried to adhere to a new truth I had just
begun to see. I might almost say that what blinded me was the brightness of
the new light. Though it in no way exonerates me, it is necessary to add that
those who adhere to the second theory are guilty of the same fault-a violation of
Thomistic principles. I hope that they, on their side, will also be able to profit from
the insights consequent upon the rectification of my error.
• This critic was Professor Anton Pegis of Fordham University. In conversations
which we had, he insisted that he was raising not merely another objection to
Position I, to be added to the seven others which I myself had raised, and five of
which I showed to be completely answerable. Vd. op. cit., Ch. VIII; THE

SOLUTION OF THE PROBLEM OF SPECIES

288

A second error followed; or, perhaps, we can regard the mistake
I am now going to report as part of one and the same error. I
t.hought that the first position had to deny a common generic
nature, in order to hold to a strict hierarchy of specific natures; but
I also realized that the logician's account of predication and of the
ordering of concepts required the notion of a common genus. The
logical account of species and genera seemed to me to be one which
the first position had to acccept, as well as the second. Hence I was
led to the false conclusion that whereas the second position could
affirm a common genus in logical analysis and a common generic
nature in the philosophy of nature, the first position could only
affirm a common genus in logical analysis. I made this an essential
point of difference between the two theories; and I formulated this
difference by saying that, according to the first position, there was
no " parallelism " between logic (concerned with the ordering of
concepts) and ontology (concerned with the order of natures) .1
This obliged me to distinguish between two types of hierarchy: the
"logical hierarchy " of concepts, in which there were common
genera; the " ontological hierarchy " of natures, in which there were
II, 106. Failure to meet this objection did not merely make the first
position less likely to be true (which was the way I regarded the failure to meet
the sixth and seventh objection against the first position) ; rather, he insisted,
failure here was tantamount to the complete untenability of the first position. I
now know that he was quite right, although at the time the difficulty he raised
about the predicability of animal seemed to me to be necessitated by the most
important point in the first theory-the very point in which the first theory
seemed to adhere to a truth which tlie second theory violated, namely, that
between man and the proximately inferior specific nature, whatever it be, only
one essential perfection exist& as the basis of the specific difference. I shall subsequently show how this truth can be preserved without committing the error Prof.
Pegis detected.
I must add that in the course o£ writing the book, I was somewhat aware of the
difficulty which Prof. Pegis later discovered. Vd. op. cit., fn. 153a, p. 128; and
fn. 189, p. 218; THE THoMisT, I, 421; II, 189. I realized that I was departing
from tradition in trying to use the word " brute " to- name the generic nature of
man; and I realized that, however I might justify such verbal usage, I could
never regard the concept brute as a genus predicable of mam., for rational brute
is a false definition by self-contradiction. Yet, at the same time, I was unable
to find a real distinction between what was intended by the concept animal, and
what was intended by the concept brute, in terms compatible with the principle of
a perfect hierarchy. Hence, in adhering to that principle, I felt I had to accept the
difficulty of not being able to explain the facts of predication.
• It will be seen at once how this mistake flows as a consequence from the
initial error of denying a common generic nature. I made it obviously as a result
of trying to adhere at once to two inconsistent principles: the principle of predication, on the one hand, and the principle of perfect hierarchy erroneously con-ceived, on the other. · Cf. fn. 6 11111pra.
THOMIST,

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MORTIMER J. ADLER

no common generic elements. 8 These mistakes were called to my
attention by the critic who charged me with violating some fundamental Thomistic canons about the relation of ens naturae and ens
rationis within the analogy of being, such as verum sequitur esse
rerum, or that the modes of predication follow the modes.of being.
As made, the charge was inaccurate on only one point: what should
have been said was that the first theory, as I conceived it, was guilty
of these violations, and hence could not be at all tenable within the
framework of Thomistic philosophy. All that the critic need have
said was that the sharp discrepancy between a logical and an
ontological hierarchy, apparently demanded by the first position,
showed that the theory was impossible for a Thomist. 9
I have now stated the error, the correction of which has such
fruitful results. 10 It might be thought that the force of the criticisms
I have just mentioned would destroy the first position and leave the
second in undisputed possession of the field; or it might be thought
that the correction of the error indicated by these criticisms would
reduce the first position to the second, thus comirig to the same
8 All of these errors, or parts of the same error, will be found explicitly enunciated
in the summary of the main points of the first position as contrasted with the main
points of the second. Vd. op. cit., Ch. VI; THE THOMIST, I, 381 ff.
9 This critic was Father Gerard Smith of Marquette University.
In a review of
my book, which appeared in Thought (Dec., 1940: XV, 59, pp.
he
obviously intended the criticism I have reported in the text; but I must confess
that I did not get the real point of his review until after many letters had passed
between us; in full truth, I should say that I did not get Father Smith's point until
I was able to see it in the light of Prof. Pegis's criticism. Just as the several
mistakes I have mentioned are parts of one error, so the points Father Smith and
Prof. Pegis made separately are really parts of one and the same fundamental
criticism. The inadequacy of my understanding of Father Smith's criticism-at
a time when I had not yet perceived the error in my formulation of the first
theory-is plainly revealed in a note I wrote on Ontology and Logic, in reply to
Father Smith. Vd. Thought, March, 1941; XVI, 60 pp. 200-4.
10 I may have made other errors than this one, but so far as I can now see this
is the only one which is relevant to the issue between two theories, in the philosophy
of nature. about the number and order of substantial species. It was this one error
which made the issue as I stated it a false issue; it is the correction of this one
error which makes the issue not only true but resolvable. The question about the
constitution of the essences of composite substances-which really is concerned
with the precise way in which the notion of " common matter " must be interpreted, when it is said that common matter enters into the composition of such
essences--is not relevant in the same sense, i. e., as determining a correct formulation of the issue, or its resolution. I think I have sufficiently shown why this
is so (Vd., op. cit., pp. 14-17, and 168-176, esp. fn. 174; THE THOMIST, II, pp.
108-116, esp. fn. 173, p. 110); and M. Maritain agrees that the fact that I have
postponed this question for later discussion is not a relevant point of criticism with
regard to the issue about species (vd. " Concerning a ' Critical Review' " in THE
THOMIST, III, p. 49).

SOLUTION

OF THE PROBLEM OF SPECIES

285

result-namely, a solution of the problem in terms of accepting the
second theory as true. But neither of these two " possibilities " is
in fact the case, precisely because the error is not essential to the
formulation of the first position, especially not with respect to the
very points on which its essential disagreement with the second
position is based. On the contrary, far from destroying the first
position, these criticisms have led to the correction of an accidental
error; and far from this reducing the first position to the second, the
correction rectifies the first theory in the line of its own essential
truth, confirms it in its opposition to the second position, and
resolves the issue by showing why the second theory must be rejected, and the first accepted.
4. Though I shall postpone until later an argumentatively adequate statement of the resolution, let me say at once how the correction came to be made, and how it is to be understood. Merely
seeing the difficulties in my formulation of the first theory was,
by itself, not enough. The criticisms which pointed out these difficulties could never, by themselves, have made me regard the
difficulties as errors, for three reasons: in the first place, I saw an
element of truth in the first theory which I could not surrender; in
the second place, I saw that this element of truth was incompatible
with points in the second theory; in the third place, I saw difficulties
in the second theory which seemed to me as insuperable as any which
attached to the first theory, if not more so. In this state of mind,
I could not give up the first theory in spite of its difficulties, nor
could I accept the second, because it had difficulties of its own. My
criterion of judgment was simply this: until all the difficulties
attaching to one theory could be removed, and until those attaching
. to the other could be shown to be incurable errors, no resolution of
the issue would be possible.
In this state of mind, I entered into a series of conversations with
M. Maritain while he was lecturing at the University of Chicago
in January. As anxious as I to clarify matters which had become
somewhat muddled by recent discussion, M. Maritain made two
points: first, that he thought both theories must concur in affirming
a common generic nature (in ontology) as well as a common genus
(in logic); second, that he thought the second theory had to agree
with the first theory's view of a perfect hierarchy of specific natures,
in which each member is, in essential grade of being, higher or lower
than a proximate inferior or superior, and in which no two specific
natures are of coordinate grade in any respect except that in which
all corporeal substances are of the same grade, namely, as corporeal

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MORTIMER J. ADLER

(i. e., as falling within the same natural genus, signified by the
presence of prime matter in their substantial composition) . At once
I found it difficult to see how the notion of a common generic
nature could be compatible with a strict view of the hierarchical
order of specific natures. This difficulty was removed when M.
Maritain and I were able to formulate a conception of the genus
as being doubly determinable even though the two species, resulting from the two determinations to which the genus was
susceptible, had only one positive difference between them. This
conception of the genus departs from the usual view which makes
it determinable by two or '11Wre positive differences, such that each
of the species within the same genus is constituted by the possession
of a perfection diverse from the perfections possessed by the other
species. In this new conception of the genus, there can be only two
species dividing it, and they divide it according as one possesses a
perfection which the other rejects; the genus is indeterminate with
respect to this one perfection, but in two ways-both as to its
possession and as to its rejection, and hence it can be common to the
two species, even though they differ, inter se, with respect to only
one perfection.U
These two points which M. Maritain made had for me more
drastic consequences than he himself, perhaps, envisaged. 12 The
source of all these consequences was the insights which occurred as
soon as we had succeeded in conceiving the genus in a way that was
completely compatible with the principle of a perfect hierarchy. I
realized then, first, that if the second theory had to agree to the first
theory's principle of hierarchy, it could no longer hold on to the
usual notion of common genus which was incompatible with strict
11 This brief indication of the new point, by which the error in the first theory
was corrected, must suffice here. An adequate analysis of the point will be given
later. Vd. Part III infra. It will be noted, furthermore, that although the point
is here stated in logical terms, it holds as well for the ontological account of generic
and specific natures, since once the error in the first theory is corrected there is no
longer any discrepancy between the logical ordering of concepts (as genua, species,
etc.) and the ontological order of natures (as generic, specific).
10 At the time he proposed them, M. Maritain
suggested that, in the light of
these points, each of the two opposing theories might be regarded as possible;
for if it admitted a common genus, the first theory was no longer intrinsically
impossible on Thomistic grounds; and even if it admitted the first theory's view
of hierarchy, the second theory might still disagree with the first about the actual
number of specific natures in the corporeal world. Hence, in M. Maritain's view,
the issue between the two theories now largely turned on the question of the
number of species-an issue which might be resolved some day by empirical evidences, or might never be resolved because of intrinsic limitations in human knowledge. In the latter case, the two possible theories would remain perennially in
opposition in the philosophy of nature.

SOLUTION

OF THE PROBLEM OF SPECIES

287

hierarchy; hence, that if the second theory could not differ from the
first with respect to the order of specific natures, it could not differ
with respect to their number; in short, that once the two theories
concurred in the principle of hierarchy, the second could not differ
from the first on any essential point, without being intrinsically and
incurably false. And, in the second place, I saw that as soon as the
first theory's denial of a common genus had been corrected by
conceiving a common genus in every way compatible with perfect
hierarchy, then the first theory became completely devoid of
difficulties: not only were the difficulties which my critics had raised
no longer present in any way; 13 but, what was even more impres·sive, the objections which I myself had raised to the first theory
(especially objection seven 14 ) could now be completely answered,
whereas before they seemed completely unanswerable. By my own
criterion of judgment, I was compelled, therefore, to conclude that
the problem of species could be resolved; that the secoi,J.d theory,
in so far as it continued to differ from the first, involved incurable
errors which made it untenable on Thomistic grounds; that the first
theory, rectified of an accidental error and, in consequence, free of
all difficulties, was true. 15
5. I shall proceed in the following order. It is necessary to begin
with some clarifications, both of the language we must use and of
tangential matters. This must be done in order to prevent certain
superficial misunderstandings which tend to obscure the whole
problem. Then, I shall undertake an analysis of the notion of
genus, showing, first, what conception of genus must be employed
in the context of a strict hierarchical ordering of species; second,
13 That is, there is no longer any difficulty about predicating
animal of brute
and man, or of cow and man, within the framework of the first theory; nor is
there any longer a lack of "parallelism" between logic and ontology, for there is
no discrepancy whatsoever between a logical hierarchy of concepts, ordered as
genus and species, and an ontological hierarchy of natures, ordered as generic and
specific. Vd. fn. 11 supra. Hence, the objections raised by Prof. Pegis and Father
Smith are fully answered: the rectified first theory does not violate the basic truth
that modes of predication follow modes of being.
14 Vd. op. cit., Ch. VIII: pp. 204-206; THE THoMIST, II, 145-147.
15 The reader may wonder whether M. Maritain
agreed to the drastic consequences which I thought followed from his own premises, and from the rectification
of the first theory accordingly. I cannot answer that question definitely here; but
later I shall report M. Maritain's reactions to the demonstrative resolution of the
problem, which I presented to him at the end of our conversations. Vd. fn. 80
infra. Beyond that, it is for M. Maritain to speak for himself on these matters;
it is my hope that he will soon write an article which will carry the whole discussion further-to what ultimate point I do not know, but I hope at least to the
point of agreement about the truth of the first theory.

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MORTIMER J. ADLER

that there is another conception of genus which cannot be so
employed; and, third, in terms of these two conceptions of genus I
shall be able to state the opposition between the first theory as
rectified and the second theory as still persisting in disagreement
with the first. The true issue being clear, it can then be resolved:
by showing why the second theory is untenable, and how the first
theory is free from difficulties. The most important part of this
demonstration will be to show that the very reasons by which the
second theory is disproved are the reasons for the truth of the
first theory. After the demonstration, I shall briefly discuss some
of the consequences of the resolution, especially concerning the
relation of logic to the philosophy of nature, for we shall find that
there are two quite different logical orderings of concepts as species
and genera, according as the principle of differentation is essential
or accidental, and when these two sorts of logical hierarchy are
properly distinguished we shall find that they image two sorts of
ontological hierarchy-the order of real essences, or specific natures,
and the order of accidental concretions, or racial natures. In a
concluding section, I shall try to suggest a solution of the historical
problem (the problem of the origin and persistence of a false theory)
by indicating how the two different sorts of hierarchy became confused, first in logical analysis, and then in the philosophy of nature.
II.

PRELIMINARY

CLARIFICATIONS

6. Like every other word in popular or technical usage, the word
" species " is ambiguous in many ways. Like every other concept,
truly possessed by the mind, the concept species is a single meaning,
a single intention. Because social words are instrumental signs
which signify through the passions of the soul, (primarily through
mental words or concepts), they have meaning; the same word
can have a variety of meanings according as it is imposed as a name
upon different things, each, of course, as understood. Because
mental words or concepts are formal signs, they do not have
meanings; they are meanings or intentions; it is their very nature
to signify their object; hence the mental word is never a name, for
it does not need to be imposed in order to signify; and the concept
cannot be ambiguous, for it cannot be any meaning or intention
other than the one it is.
Now if the word "species" were unambiguously used, if the word
" species " were always used, even by philosophers, to signify what
is intended by the concept species, the discussion of certain philosophical problems would be much simpler. But we know that that
is not the case, and, furthermore, that we can never expect it to be.

SOLUTION OF THE PROBLEM OF SPECIES

That being so, we must make strenuous efforts to save discourse
from the failures of communication which always threaten us
because of the difficulties intrinsic to the use of language. And these
difficulties are peculiarly acute in the case of such words as " species," "genus," "difference," etc., because of the peculiar character
of the concepts through which these words sometimes signify, in one
of their many usages. Let me explain.
Concepts can be divided into two sorts: they either terminate
the direct act by which the intellect understands real beings, or they
terminate the reflexive act by which the intellect understands its
own acts and the concepts, or so-called logical beings, which are
involved in the intellect's direct acts of understanding. This is the
basic distinction between the first and second intentions of the
mind. Now, whereas it is true that certain concepts are purely and
exclusively second intentions, it is not true that every concept,
other than these, is purely and exclusively a first intention. The
reason for this is simply that every concept, other than those which
are purely second intentions, can function both in the mind's direct
acts of understanding and in its reflexive acts. To make this plain,
let us consider two judgments: (1) a judgment expressing an act
of direct knowledge, such as "John is a man"; (2) a judgment
expressing an act of reflexive knowledge, such as " man is a species
(or a concept, a universal, a predicate, etc.)." In the first ·type of
judgment, the concept man functions as a first intention, for it is
that whereby we understand the real nature of this singular substance. In the second type of judgment, the same concept man
functions, in a special way, as a second intention, for it is itself now
the object being understood. I refer to the way in which the concept man functions as a second intention as " special " because it is
not the same as the way in which the concept species functions as a
second intention in the same judgment. The latter concept is a
second intention in the primary sense of being that whereby we
understand the ideal nature of this particular concept, the concept
man. In short, just as judgments which express acts of direct
knowledge are constituted by subjects and predicates, so also are
judgments which express acts of reflexive knowledge; and just as
both subject and predicate in the direct judgment must be first intentions, so the concepts, which are subject and predicate in the
reflexive judgment, must both be second intentions. But only
certain concepts can function as predicates in reflexive judgments.
(These are such concepts as concept itself, predicate, universal, and,
of course, the concepts traditionally known as the five predicables
or the five universals, genus, difference, species, property, accident.)
8

MORTIMER J. ADLER

All concepts other than these can function as subjects in reflexive
judgments, but they can also function as either subjects or predicates in direct judgments. Furthermore, the concept which can
function as either subject or predicate in a direct judgment, as well
as the subject in a reflexive judgment, can never function as the
predicate in a reflexive judgment; whereas, in sharp contrast, the
concept which can function as the predicate in a reflexive judgment
may also be able to function as the subject in such a judgment (as
when we say " species is a universal ") but it can never function
either as subject or as predicate in a direct judgment.
This distinction between two sorts of concepts can be summarized as follows. Let us use the phrase " logical concept " to
name those few concepts which are primarily and exclusively
second intentions. And let us refer to all other concepts, which are
primarily first intentions though they may also be the subjects
of second intentional judgments, by using the word " concept "
without qualification. It will be seen at once that whereas all
concepts are logical beings, beings of the mind, entia rationis as
divided against entia naturae, only some concepts, in fact a very
small number, are logical concepts. 16 Furthermore, let us dis16 An interesting
ambiguity in the word "logical " is discovered by comparing
its two uses in this sentence. In its first use, the word " logical " signifies one of
the divisions of being, and has a connotation closely related to that of the words
" ideal " and " mental " as opposed to the signification of such words as " real "
and " physical." In its second use, the word " logical " signifies that the concepts
so described belong peculiarly to the science of logic. Logical concepts are the
fundamental categories in terms of which the logician analyzes all concepts. The
science of logic has its own proper categories of analysis, just as the science of
metaphysics has its own fundamental terms, the transcendentals, which can be
called " metaphysical concepts "; or just as the science of grammar has its own
basic categories, i. e., the parts of speech, which can be called " grammatical
concepts."
There are, unfortunately, several meanings of the phrase " ens rationis." I
am using it here to make the division between two modes of existence which any
essence or res can exercise: real, or physical, and intentional, or mental. In this
way ens rationis is divided against ens naturae according to the distinction between
what exists in the mind (but can also exist apart from it) and that same thing
(res) as it exists apart from the mind in the real order. But ens rationis is also
distinguished from ens reale according to a different principle: that is said to be an
ens rationis which can exist only in the mind and cannot exercise any real existence.
John of St. Thomas divides entia rationis of this sort into two kinds: negations,
privations, fictions, on the one hand, and relations of reason, or pure second intenA. 1.) As
tions, on the other. (Vd. Cursus Philosophicus, Logica, Pt. ll, Q.
I shall use the phrase " ens rationis " I shall mean only those concepts which have
a fundamentum in re, and never those which have no fundamentum in re; concepts which have a fundamentum in re can be either first intentions or second
intentions; and this is to say that I shall be considering only real things in so far
as they exercise intentional existence under a primary or secondary mode of

SOLUTION OF THE PROBLEM OF SPECIES

tinguish two modes of the second intention. According as a concept
functions as the subject of a judgment in the second intention, it
signifies itself as the object of thought. Let us speak of it as a
second intention reflexively. According as a logical concept functions as the predicate of a judgment in the second intention, it
signifies some aspect of the nature of the subject-concept which is
the object of thought in this case. Let us speak of it as a second
intention predicatively. (There is, of course, no need for a similar
distinction between the subject-concept and predicate-concept of a
judgment in the first intention; for in so far as both concepts are
universals, both are first intentions predicatively, even though one
may function as the subject of the judgmenU 7 ) Hence we can say
that only logical concepts can function as second intentions predicatively (though they may also function as second intentions
reflexively); whereas ordinary concepts (non-logical concepts in
the precise sense already indicated) can never function as second
intentions predicatively, but either as first intentions or as second
intentions, but then only reflexively. 18
intellectual consideration. It is only in the first mode of distinction between
ens naturae and ens rationis that ens is said analogically of the same res exercising
a different esse (real or intentional) . In the second mode of distinction, ens is
said equivocally, as John of St. Thomas points out; but I would exclude relations
of reason (pure second intentions) from this equivocation, for they· are real
things under a secondary mode of intellectual consideratiou, and therefore must
be distinguished from negations, privations and chimerae. (Cf. St. Thomas,
Summa Theologica, I, 16, 8 ad
It is interesting, further, to observe that the
division of the real into the actual and the possible is paralleled by a similar
division of the rational into the possible and impossible (i. e., respectively capable
and incapable of having a fundamentum in re); and that which is rationally
possible, in this sense, i. e., capable of realization, may be either really actual or
really possible, whereas that which is purely ideal in the order of reason can never
be really actual.
17 All predications in the first intention are ultimately
of first substances. The
primary distinction, therefore, in the case of all judgments in the first intention
is that between the singular and the universal judgment, according as the subject
of the judgment is a singular or a universal term. The subject of a universal judgment is always a first universal intention predicatively, in the sense that that
same concept can always be a predicate in a singular judgment, in which the
subject-term is a singular, and not a universal, intention. That the judgment " man
is an animal " is in the first intention can be seen in two ways: (I) Both subject
and predicate are predicable of a singular term, such as" John."
It is indifferent
whether the grammatical form of the judgment be " man is an animal" or " men
are animals." By the same criteria, "man is a speCies" is seen to be in the second
intention because (1) the predicate is not predicable of any:·singular term, and
" men are species " is nonsense.
·
18 To be sure that these distinctions are plain, let me give a parallel analysis in
the field of words,. with respect to the impositions. The first imposition of a word
is as a name imposed upon that which is not a word, but a thing to be signified.

MORTIMER

J. ADLER

There IS one further point which complicates the analysis of
intentions. Just as it is true that the agent intellect is never not
active, just as it is true that there is never an act of intellect unaccompanied by an act of imagination, or conversely, so also is it
true that the human mind is always reflexive, by which I mean that
there is never a purely direct or a purely reflexive act of the intellect.
Whenever we understand anything, we also understand our act of
understanding; and we can never understand our act of understanding unless our intellect is in act understanding something. 18 "
Of course, the fact that there is never a temporal separation of
direct and reflexive intellectual acts does not mean that we cannot
discriminate between these two modes of intellectual activity;
and this distinction is not purely analytical for it is a real distinction
on the part of intellectual activity itself. Were this not so, we
could never have discovered the distinction between the first and
the second intentions of the mind. Thus, we are led to see that no
concept is ever purely a first intention. 19 In every ordinary concept
The second imposition of a word is upon another word, and not upon a thing; it is
an imposition made for the sake of naming the class of words to which a given
word can belong. Thus, in the sentence, "John is a man," both the word "John "
and the word " man " are first impositions; but in the sentence " man is a noun,"
the word "noun" is clearly a second imposition. Now, in the latter sentence, the
subject-word " man " is used to refer to itself as to that which is being talked
about. As thus used, it is not a first imposition nor is it a second imposition in
the same way that the word " noun " is. Therefore, we must distinguish two
kinds of second imposition: a reflexive second imposition (i. e., the use of a word
to refer to itself) a predicative second imposition (i. e., the use of a word to
talk about another word).
Now, the words which signify the concepts of
grammatical analysis are the only words which are purely second impositions,
i. e., capable of being used in the second imposition predicatively.
(Cf. fn. 16
supra.) In contrast, all other words are primarily first impositions, although they
can be used in the second imposition reflexively, when we try to talk about them
as words, rather than use them to talk about things which are not words. The
parallelism of these grammatical distinctions with the logical distinctions already
made should be clear. In the judgment, "John is a man," the concept man
is a first intention.
In the judgment, " man is a species," the concept species
is a second intention predicatively, whereas the concept man is a second intention
reflexively.
18 • What is here said is equally true of first and second intellectual
acts-<lf
conception as well as of judgment, or judgment as well as of conception.
19 I am here treating
only of the formal concept, the medium quo of understanding. The objective concept, which is at once the medium quod and the
quid of understanding, must be analyzed differently. Considering the objective
concept as the objectification of the thing whereby it becomes an object of understanding, we see that it is not susceptible to the same distinction between first
and second intentions. If we restrict the word " intention " to name only that
which functions as a formal sigu, then only formal concepts are intentions;
though, of course, in another sense of the word, we must speak of objective

SOLUTION OF THE PROBLEM OF SPECIES

293

there is a second intentional note in addition to its first intentional
note which is its signification of the thing-as-intended. In other
words, no concept functions as a first intention, in the direct act
whereby we understand a thing, without its being understood as a
universal, as a result of the reflexive act whereby we understand the
concept itself. The intention of universality (which is a second
intention) must be present in the concept man when we use that
concept, either as predicable of many or as a universal subject of
predication; 20 And when a concept, such as man, is used as a
predicate in a direct judgment, it contains a further second intentional note, such as the intention of species. Although no fully
'developed concept is ever purely a first intention (devoid of all
second intentional notes), there are some concepts, the few we
have called "logical," which are purely second intentions. Yet
even these contain implicitly the first intentions from which they
are derived. Just as the concept man contains implicitly the notion
of particular men, so the concept species contains implicitly the
notion of man or cow or whatever can properly be regarded as
a species. Thus, the omnipresence of reflexivity in all intellectual
acts is not violated by concepts which are primarily first intentions,
and the omnipresence of direct understanding is not violated by
those logical concepts which are primarily second intentions;
though it should be noted, of course, that the way in which second
intentional notes are present in ordinary concepts is not the same
as the way in which first intentions are implicit in logical concepts. 21
The foregoing exposition is for the sake of clarifying the use of
concepts as intentional, rather than as real, beings. In fact, when a formal concept which is primarily a fust intention, functions as a second intention reflexively,
and thus becomes an object of thought, it also becomes the objective concept of
the nature: it is that nature-as-understood, now under a secondary mode of
consideration.
20 It is true to say, therefore, that second intentions are drawn from fust intentions, because every concept which is a first intention, implicitly contains second
intentional notes. Vd. John of St. Thomas, Cursus Philosophicus, Logica, Pt. IT,
Q. 2, A. 2.
21 In the ordinary concept, the second intentional note must be explicitly present
in order for the concept to function perfectly as a subject or predicate in a univeisal judgment; but in the logical concept the first intentional note is present
only implicitly, and that is why the logical concept can be said to be not only
primarily but purely a second intention. Just as singulars are implicitly present
in every first intentional universal, so fust intentional universals are implicitly
present in every second intentional universal. The judgment " man is a species"
is the analogue, in the second intention, of the singular judgment in the first
intention, i. e., " John is a man "; for just as there are many singular instances
of man, so there are many individual concepts which are instances of species. Cf.
St. Thomas, In Perihermenias, Bk. I, 7, Lect, 10, # 9.

MORTIMER J. ADLER

such words as " species " and " genus." Their ambiguity is more
difficult to control than that of most words, because in one of their
usages they signify either the logical concepts species or genus,
or the second intentional note (the intention of species or genus)
which is present in ordinary universals, such as 7/ULn and ani11ULl.
If this were their only usage, we should have few difficulties; but,
unfortunately, these words are used in discourse about the nature
of things, as well as in purely logical discourse about concepts.
This is true of all the words which have been used to name the
predicables. Thus, the words " property " and " accident " are
certainly used in ontological discourse, as well as in the science
of logic. And there can be no question about the word " species "
being used both ways. The passages in which Aristotle and St.
Thomas use the word " species " in a way that does not directly
refer to either an ordinary or a logical concept are much too numerous to cite. I shall content myself with merely indicating some of
the contexts in which such usage occurs: in Aristotelian works
concerned with the classification of plants and animals; in Thomistic
treatises on creation or the work of the six days, in which, for
example, it is asked whether God created the species of corporeal
substance in act or in their causes, or in which it is said that in
things generable and corruptible the individual is for the sake of
the species; in the treatise on angels, who are spoken of as species;
in the Thomistic consideration of man, in which specific human
nature is discussed in terms of its relation to all infra-human species;
and in all modern scholastic discussions of biological science and
the theory of evolution, in which an effort is made to distinguish
between natural and systematic species. In all these contexts, what
is being talked about when the word " species " is used is certainly
not, in the first instance, an idea, neither an ordinary concept nor
the logical concept which is one of the five predicables.z 2
But the question may be .raised at once whether the purely
second intentional concept species is not always being somehow
referred to whenever the word " species " is used in any way, even
though perhaps it is not being referred to directly or in the first
instance. I think the answer is, with unimportant exceptions,
definitely affirmative. A full understanding of this affirmation is
necessary for the clarification in which we are now engaged; and
in order to achieve this understanding it is necessary to consider
further the various dimensions of verbal ambiguity.
•• It is unnecessary to go through the same enumeration for the word " genus."
Its range of ambiguity in a variety of contexts is approximately the same as
that of the word " species," though as we shall see later the word " genus " raises
some problems of usage peculiar to itself.

SOLUTION OF THE PROBLEM OF SPECIES

295

The first and simplest way in which most words are used ambiguously is their being used to signify quite different things, when
the medium of their signification consists of different concepts.
Thus, the word " species " can be used to signify gold or silver coin;
and this usage of the word in monetary theory appears to be
equivocal when contrasted with the usage of the same word in
logical theory. Let us call this type of ambiguity " notional." 23
Another, more subtle, and less often recognized, type of ambiguity
is that which attaches to words because they can be used in the first
or the second intention. Let us call this type of ambiguity "intentional " and proceed with its analysis.
Mental words (concepts; formal signs) are intentions. Social
words (physical notations; instrumental signs) have intentions:
whatever intentions or significations they have accrue to them from
the concepts through which they signify when they are imposed
as names. As notionally ambiguous, a word in two usages signifies
differently because in the two cases it signifies through distinct
concepts (e. g., the notional ambiguity of the word " species ") .
But as intentionally ambiguous, a word has a single mode of
signification notionally (i. e., it signifies through a single concept),
but in that single mode of signification there is a duplicity of
intentional notes. The only words which can be used without
intentional ambiguity are those which are used as purely· proper
names. All other words, all strictly communicable names, since
their mode of signification is through concepts or universals, have
intentional ambiguity in usage precisely because of the point already
made, namely,that no ordinary idea is ever purely a first intention.
The easiest way to detect the intentional ambiguity latent in all
common names is by examining these formally invalid syllogisms:
"John is a man, man is a species, John is a species"; " man is an
animal, animal is a genus, man is a genus." These syllogisms are
formally invalid because they commit the fallacy of four terms.
But the duplicity of the " middle term " is not due to notional,
but to intentional, ambiguity. In each case, the word expressing
•• It is unimportant for our discussion that this use of " species " is now obsolete, the word " specie " now being used for coin of the realm. I had in mind
this equivocal use of the word " species " to signify coin, when I said there were
some unimportant exceptions to my affirmative answer to the question raised in the
preceding paragraph. Other interesting examples of notional ambiguity in familiar
philosophical words are: the use of the word " essence " in metaphysics and chemistry; the use of the word " substantive " in law, in gra=ar, and in metaphysics.
I am not here concerned with whether these ambiguous usages are always equivocal, or whether they are sometimes analogical in the metaphorical or attributive
mode. Yd. the 9 meanings of "species" listed in the large Webster.

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MORTIMER J. ADLER

the middle term in the minor premise signifies through a concept
as a first intention, whereas the same word expressing the middle
term in the major premise signifies through the same concept as a
second intention. 24 One of the formal rules of valid syllogizing
should therefore be that the three terms must be concepts uniformly in the first or the second intention. From a direct judgment
as one premise and a reflexive judgment as the other, it would
appear that no conclusion can be validly drawn, because the
premises violate the rule of uniformity of intention. 25 I say "appear" because there is one way of drawing a conclusion from
premises which are heterogeneous as to intention. Thus, from
"John is a man," and "man is a species," we can conclude that
"John has a species," or to speak more precisely, "John has a
specific nature." Similarly, from "man is an animal" and "animal
is a genus," we can conclude that " man has a generic nature."
This way of drawing a conclusion, in spite of the intentional ambiguity of the word expressing the middle term, shows us a good
rule for solving the intentional ambiguity of communicable names
in general, and of such words as "species " and " genus " in
particular.
Whenever the word " species " or the word " genus " is used in
the first intention, as is the case in ontological discourse, it must
always be used as signifying a specific nature or a generic nature;
and it can signify in this way only if the medium of its signification
is a specific concept or a generic concept. But a specific concept such as man, is not the concept species; nor is the generic
concept animal the concept genus. And a particular concept, such
as man, can not be reflexively understood as specific unless it is
•• It may be thought that the fallacy of four terms is grammatically indicated
by the fact that the grammatical predicate of the sentence expressing the minor
is " a man " whereas the grammatical subject of the sentence expressing the major
is "man." This, however, is an accident of English usage; it does not occur, for
example, in Latin: "Petrus est homo, homo est species, Petrns est species."
•• This rule can be stated in other ways: grammatically, the word expressing
the middle term must be intentionally, as well, as notionally unambiguous; logically, the concept which is the middle term must function either as a first intention or as second intention in both judgments. (If it could not function in both
ways, we would not have this problem of restricting the concept to its first or its
second intentional notes.) The rule has further implications. The logical canon
that all predication is of first substances is true only of predication in the first
intention. Predication in the second intention is always of second substances as
the ultimate subject. That is why when the major predicate is a second intention, it cannot be predicated through the middle term, if that middle term as a
predicate is first intention. Duplicity of intention in the "middle term " violates
the rule that whatever is predicated of a predicate can be predicated in turn of its
subject.

SOLUTION

OF THE PROBLEM OF SPECIES

understood as a species, i. e., as subject to the reflexive judgment
in which the logical concept species is predicated of this ordinary
concept man; furthermore, it should be said that this reflexive
judgment merely explicates the second intentional note, species,
already present in the concept man, which is primarily a first
intention. 25 " We have here, then, a series of related significations of
the word " species." And it is obvious at once that the primary
signification must be the logical concept species, for, in the first
place, it is only through this concept that the word " species " can
be used derivatively when it signifies a given concept, such as man,
as a species or as specific; and, in the second place, it is only through
a concept, such as man, explicitly understood as specific, that the
word " species " can be further used derivatively when it signifies
a given nature, e. g., human nature, as specific. This shows that
the intentional ambiguity of the word "species "-when used in
these three senses-is not sheer equivocation; on the contrary, the
three significations are related here as the significations of a word
used analogically in the attributive mode. 26 Our understanding of
what it is for any concept to be a species depends upon our possessing the concept species itself; thus, our concept species is the
cause of our understanding the concept man as specific; and,
furthermore, our understanding of the concept man as specific is the
cause of our understanding John as having a specific nature. Hence
any use of the word " species " other than in the second intention
to signify the concept species itself is a derivative usage dependent
upon that primary usage. Even when the word is used in the
second intention to signify the concept man as specific, the usage
is derivative; and it is certainly derivative when we use the word
in the first intention to signify a nature as specific, a nature we have
come to understand by means of a specific concept.
To summarize the discussion thus far: (1) The concept species
is always a logical concept (a second intention); it is never an
25 " It is worth observing, in terms of the Kantian distinction between explicative
(analytic) and ampliative (synthetic) judgments, that all judgments in the second
intention are explicative.
26 It is not important
to raise the question here whether the use of the word
" specific " of both concept and nature is a case of the analogy of proper proportionality, rather than of attribution.
Viewing the specific nature and the
specific concept as the same res exercising two analogical modes of existence, real
and mental, we may have ground for thinking that the analogical use of the word
But even if it
" specific " in the two cases is proportional rather than attributive.
is proportional, viewed in one way, it can also be attributive, as viewed in the
causal order of knowing and naming. Certawly, the use of the word " species "
to name the concept species, and the use of the vord "specific" to signify a logical
property of an ordinary concept, is a case of derivative naming by attribution.

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MORTIMER J. ADLER

ontological concept (a first intention). (2) An ordinary concept,
such as man, is never a logical concept; but although it is primarily
an ontological concept (a first intention), it always includes second
intentional notes, such as the intention of specificity. (3) The word
" species " is not only notionally but intentionally ambiguous; as
intentionally ambiguous, it can be used either in the first intention
or in the second; as used in ontological discourse (in the first intention) it is used to signify natures as specific; as used in logical
discourse (in the second intention) it is used to signify either (a)
ordinary concepts, such as man, as specific, or (b) the concept
species itself. Of these three related usages of the word "species,"
only the last is primary; the other two are derivative, and the first
more so than the second. (4) The word" man" is also intentionally
ambiguous, as indicated by the invalid syllogisms which we
examined: it can either (a) signify through the medium of the
concept man functioning as a first intention in ontological discourse, or (b) signify the concept man itself, functioning in logical
discourse as a second intention reflexively .26 "
I think I have now clarified a point which seems to have caused
much trouble to some readers of The Problem of Species.27 When I
spoke of "ontological species" and" logical species," I did not mean
that there were two kinds of species. I certainly did not mean that
actual universals existed outside of the mind and apart from knowledge.28 Regardless of the purity of my intentions, my manner of
speaking seems to have had unfortunate consequences, from the
••• Cf. St. Thomas, In Perihermenias, Bk. I, 7, Lect. 10, # 9, wherein he enumerates four modes in which a universal concept can be employed.
27 Vd. op. cit., Preface, in which M. Maritain
writes: "The notion of species is
in itself a logical notion. . . . This notion, logical in itself, can be employed
either from the logical or the ontological point of view.. There is no reason,
therefore, to distinguish two sorts of species, logical and ontological species. It is
the same species or the same genus, which can be employed in either a logical or
an ontological sense; that is, either to designate a universal as it exists in the
mind, or to designate the fundament which the universal has in things " (pp.
ix-x). I take it that Mr. Maritain is here saying that the notion of species is
strictly a logical concept; and that any use of the word " species " to signify
anything other than the concept species itself, is a derivative mode of signification.
Strictly speaking, the concept species is never used ontologically; the word
" species " can be used ontologically, and so can ordinary concepts, such as man,
which may include the intention of species among their notes. That M. Maritain's and my understanding of these matters converge can be seen from what
he later wrote, in reply to misapprehensions of my language: vd. " Concerning
'A Critical Review,' " Zoe. cit., pp. 46-47.
28 Vd. op. cit., pp. 12 ff.; THE THoMisT, I, 90 ff.: "When I speak of ontological
species, I am using the word 'species ' in the first intention to refer to the specific
nature of an existing composite substance."

SOLUTION OF THE PROBLEM OF SPECIES

point of view of communication. In order to prevent any further
misunderstandings, I shall adopt the following rules of usage. I
shall henceforth never use the word " species " (or similar words,
such as " genus " and " difference," in the first intention. Whenever,
in the context of ontological discourse, I am treating of natures
I shall use such words as " specific " or " generic " to convey the
distinctions (derived from the concepts species and genus) which
are applicable to such natures. 29 I shall restrict my use of the word
" species" (and "genus" and "difference") to the context of
logical discourse, in which, using them in the second intention, I
shall be referring either to the logical concepts of species, genus,
and difference themselves, or to ordinary concepts considered as
a species, or a genus, or a difference. Finally, whenever I use a word
like" man" or" animal" I shall try to indicate whether I am using
it in the first intention, as a term in ontological discourse, to name the
specific or generic nature of an existing substance; or in the second
intention, as a term in logical discourse, to name the specific or
generic concept through which that nature is understood. 80
To complete the verbal clarification, some comment on the words
" ontological " and " logical " is needed. Here we are concerned
with notional, not intentional, ambiguity. We have already seen
two related meanings of the word "logical": (1) as qualifying
the word " being " and (2) as qualifying the word " concept." In
the first usage, the word " logical " is used to signify a distinction
within the analogy of being, i. e., between two modes of being,
•• The most difficult word is "difference." I shall try to refrain from using this
word in the first intention, for otherwise I would have to speak of the differential
nature, just as I speak of the generic nature-the two together being the copene'
trating principles of the specific nature.
30 I hope the reader will realize that it was not out of sheer perversity or negligence that I adopted a looser vocabulary in The Problem of Species. I could not
have quoted and commented on countless passages in the writings of Aristotle,
St. Thomas and contemporary scholastics, without using the wDTda " species "
and " genera " as they are generally used-very loosely, i. e., both in the first and
in the second intention, both in ontological and in logical discourse. In order to
prevent confusion, I tried to use the words " ontological " and " logical " as qualifiers so as to indicate in what universe of discourse the words " species " and
" genus " were being used at every point, in the passages quoted or in my own
writing. But the use of the qualifiers seems not to have worked; in fact, they
caused worse confusions than they were aimed to cure. I must now ask the
reader to abide by the strict canons of usage I have set up for myself. I shall
leave to him the task of interpreting the many passages in traditional texts
which use words much more loosely. May I add one thing more: if I had adopted
the strict usage I shall now employ, I would have had to entitle my book "The
Problem of Specific Natures" for, as a work in the philosophy of nature, that
was its primary concern, not species.

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MORTIMER J. ADLER

real and mental, according to which a res exercises physical or
intentional existence. In the second usage, the word " logical"
is used to signify a distinction within the order of mental being
itself, as between all ordinary concepts (which are primarily first
intentions and are primarily used in ontological discourse) and a
special set of categories (which are exclusively second intentions
and are exclusively used in the science of logic). Thus, all judgments are logical in the first sense, but only those judgments which
a man makes in his technical role as a logician are logical in the
second sense.
The word "ontological" has three related meanings, through all
of which runs a note of contrast to the meaning of " logical," in
both its senses. The primary use of " ontological " is as a qualifier
of the word "knowledge." Just as being is divided into real and
mental (or logical) , so knowledge of being is divided into ontological (or knowledge of real being, direct knowledge, employing
concepts as first intentions) and logical (or knowledge of mental
being, reflexive knowledge, employing concepts as second intentions). But there are at least three grades of knowledge of the real:
of being as such, of mobile being, of the phenomenal manifestations
of mobile being. Hence, we can use the word "ontology" in the
narrowest and strictest sense to designate metaphysics; or more
broadly to designate all philosophical knowledge, including both
metaphysics and the philosophy of nature; or most broadly, to
designate all knowledge of the real, including the natural and even
the social sciences as well as philosophy. Since the problem of the
order and number of specific natures requires us to consider the
findings of the natural sciences as well as the principles of the
philosophy of nature, I used the word " ontological " in the broadest
sense to name all knowledge of the real, in contrast to "logical"
as naming the science of logic. Hence, in one pair of their opposed
meanings, I used " ontological " and " logical " to refer to distinct
universes of discourse, radically different types of knowledge. But
just as the word" logical" can be used (unfortunately so, I think)
as a synonym for mental, qualifying the word " being," so can the
word " ontological " be used as a synonym for real, also qualifying
the word "being." 31 Hence, when I spoke of an ontological as
opposed to a logical hierarchy, I meant, in the first instance, a
81 This usage of " ontological " seems to me to be no more regrettable than the
similar usage of " logical." The primary usage of both words is to name spheres
of knowledge; the derivative use of a name for a kind of knowledge to name the
kind of being thus known has always seemed to me the sort of appellation most
likely to result in a variety of confusions.

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hierarchy of natures, in the order of real being; in the second instance, a hierarchy of concepts, in the order of mental being.
Of course, it follows that our exposition and explanation of an
ontological hierarchy is the work of ontological knowledge, just as
the setting fort of a logical hierarchy is the work of logical science.
In the light of the foregoing I shall continue to use the words
" ontological " and " logical " as a pair of opposites in the two related senses just indicated. 32 This verbal clarification also enables
me to make two other preliminary points.

(I) For the purposes of our present discussion, we need not
consider the problem of the ontological vs. the logical, as that occurs
in metaphysics. I am here referring to the metaphysical account
of the analogy of being as including these two fundamental modes
of existence: real, or physical, and intentional, or mental. We need
only to proceed in the light of that analysis, in terms of such truths
as verum sequitur esse rerum, and the axiom that modes of predication follow modes of being. 33 No solution of the problem of species
and specific natures can be sound if it violates any of the metaphysical truths about the analogy of being, and particularly about
the correlation of real and intentional existence: i. e., the sameness
of the nature or res, which is able to remain the same while
exercising these two modes of existence. 34
But we are concerned with the problem of the ontological
vs. the logical, as that occurs in epistemology. I am here thinking
of the problem of how these two spheres of knowledge are ordered
to one another. The oft-cited fact that the science of logic considers,
in its own way, everything which falls within the scope of all other
bodies of knowledge (i. e., all knowledge of the real) ,S 5 does not solve
•• If these usages had been understood, it would have been understood that
when I said " species ontologically considered," I meant the object which is
being considered when a philosopher of nature or a natural scientist uses the word
" species " as a technical term in his universe of discourse--namely, a specific
nature.
•• Vd. Yves Simon, L'O'I'ttologie du cO'I'tna!tre, Paris, 1934; Fr. G. B. Phelan,
"Verum Sequitur Esse Rerum," in Mediaeval Studies, Vol. I (New York,
1939): pp.
and J. Maritain, The Degrees of Knowledge, New York, 1938;
an,d A Preyace to Metaphysics, New York, 1939.
•• This, as I have already pointed out, was one of the main contentions in
Father Smith's review (vd. fn. 9 supra), and it was warranted by the accidental
error in my formulation of the first position-an error which caused the first theory
to violate the correlation between real and logical being.
1004b
and St. Thomas's commentary
•• Vd. Aristotle, Metaphysics, IV,
on this passage, In Meta., IV, lect. 4, 574: "Now, the beings of reason are comparable with the beings of nature, because all the beings of nature fall under the
consideration of reason, and thus the subject of logic extends to everything about

MORTIMER J. ADLER

this problem. Although the spheres of logic and of ontology (in the
broadest sense) are co-extensive, the two kinds of science are not
simultaneous: each in its own way has a certain priority over the
other. Thus, in the order of analysis, the logician has priority with
regard to the notion of species, for species is exclusively a second
intention; and when the philosopher of nature or the natural
scientist uses this notion, he borrows it from the logician. This is
seen in the fact that any employment of the word " species " or the
word "specific" in the first intention is a derivative usage. 36 But,
in the order of learning and discovery, first intentions are prior to
second intentions, and here the student of nature, philosopher or
scientist, takes priority. Nature itself is prior to knowledge of
nature, and knowledge of nature, in turn, is prior to knowledge of
knowledge. H there were not in fact substances differing specifically (i. e., diverse in specific nature), we could not in truth form
concepts of these natures, which contained the intention of specificity, and hence we could never have derived the concept species
itself. This fact about priority is extremely important to the
philosophy of nature. Although he must listen to the logician with
regard to species and genus, the philosopher of nature speaks first
when it comes to saying how many specific natures there are, how
they share generic natures, how they are ordered, etc. There need
be no conflict between logic and ontology in the consideration of
these problems, in which they both have an interest; but there
will be conflict, with consequent confusions and errors, unless the
two spheres of knowledge are well-ordered to one another. Thus, it
is not for the logician alone to say whether the concept man is truly
a specific concept; he can say what the formal properties of any
concept must be in order for it to be a species or a genus; but the
interpretation of the facts of nature in the light of strictly ontological principles is indispensable for the final determination whether
this or that concept is a species or a genus. 81 Logicians, or readers
which the being of nature is predicated. Whence Aristotle concludes that the
subject of logic is equated to the subject of philosophy, which is the being of
nature."
•• The concept species is a second intention even when it lends its significance to
the word " species " as used in the first intention to designate a specific nature;
and even when it enters, as a second intentional note, into the signification of a
concept, such as man, which is primarily a first intention.
17 This, I take it, is M. Maritain's point in saying: " It is true that for his own
comfort and for the sake of exemplifications, the logician often uses practically as
species many objects of thought (for instance, ' the dog,' animal latram, ' the
stone,' ' the lion ') which are not necessarily true species in the ontological sense
(nor, therefore, in the logical one). In this sense I would agree in distinguishing
between ' ontological species ' and ' (improper) logical species ' " (Problem. for

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303

of logic, who fail to realize this fall into grave error, the sort of
error which can become an obstacle to truth in the philosophy of
nature, in so far as the student of nature must employ the logical
concepts of species and genus. But falsity in the philosophy of
nature can also cause errors in logic, for if the logician is misled
by the naturalist to make wrong discriminations among concepts
(e. g., between those which are and those which are not properly
specific) , he may develop a false or confused analysis of species and
genus. In fact, both of these mistakes have actually happened
in the history of philosophia perennis: falsity in the philosophy
of nature has caused errors in logic, and errors in logic have been
an obstacle to reaching the truth about nature. 38
7. There is one other matter which requires preliminary discussion. Unlike the previous points of verbal clarification, this
concerns the problem of universals. In order to proceed with the
discussion of species and specific natures, it is not necessary to give
a complete account of this matter, but it is necessary to be sure
that everything which is to be said will be understood in terms of
the doctrine traditionally called " moderate realism."
There is no problem about the object of logical knowledge.
Whether he is concerned with concepts, judgments, or syllogisms,
the logician is always dealing with actual universals, for he is
dealing with entia rationis. But there is a problem about the object
of ontological knowledge, be it philosophy or science. The object
of such knowledge is not the singular as such; but neither is it the
universal as such (i. e., the actual universal as it exists in the mind) .
What does it mean, therefore, to say that the scientist and philosopher seek to know the natures of things? This question must be
answered within the restriction imposed by two facts: (1) the
nature of a thing does not exist as a universal in the order of the real;
Thomists, Preface, fn. !i!, p. x). Cf. op. cit., fn. U9a, p. 94; THE TBoMIBT, I, fn.
129a, p. 892. In short, the philosopher of nature must tell the logician which
natures are truly specific, before the logician can discriminate among concepts as
'JITOper and im'JIToper species. I shall return later to an explanation of the true
significance of those concepts which are ltere called "improper species." But
henceforth I shall speak of proper species ,and genera whenever I wish to indicate
that what is conceived by the concepts so named are really specific and generic
natures.
88 I will return to this whole matter in the concluding part of this article wherein
I shall try to account, historically, for the origin and persistence of the false
theory of species, i. e., the second theory. Here I have tried only to point out
why the epistemological problem of the relation of logic and ontology is important to us: i. e., because of the way in which these disciplines can interfere with
each other, and infect each other with errors.

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(2) the nature of a thing is known universally, i. e., as a nature
somehow common to a plurality of individual existents.
The question is answered by St. Thomas when in discussing
cognition he contrasts two false extremes with each other, and with
a moderate middle position. 39 On the one hand, there is the extreme
of nominalism and materialism. This combines one truth and one
error: the truth is that all existents are individual; the error is that
all human cognition is sensitive, i. e., an apprehension of the
singular as such; from which the false conclusion is drawn that all
common or communicable names are "universal " only by arbitrary
imposition upon many, and without the benefit of a truly universal
mode of signification. On the other hand, there is the extreme of
realism and idealism. This combines one truth and one error: the
truth is that human cognition is by an intellectual as well as by
a sensitive faculty, the distinct faculties having diverse formal
objects, i. e., the singular and the universal; the error is that the
intelligible object is like the sensible object, in being actual prior to
being known, and in existing in the same manner as it is known;
from which the false conclusion is drawn that actual universals
exist apart from the knowing intellect. Between these wrong
extremes lies moderate realism which combines the truth and excludes the errors which are found in the extreme positions. With
one extreme, it affirms that only individuals exist in the order of
the real; with, the other extreme, it affirms that man knows intellectually as well as sensitively, and knows intellectually by means
of universal concepts through which the thing (res) is objectified
in a universal objective concept; from which it draws the true
conclusion that the intelligible object does not really exist as it is
known. In the order of real existence, the intelligible object is
potential, i. e., a nature understandable universally; in the order of
the understanding itself (the order of intentional existence), the
same thing (res) is no longer intelligible (i. e., potential, understandable), for it is now intellected (i. e., actual, understood) . As
actually understood, it is an actual universal, where before, as potentially understandable, it was a potential universal."' 0
Vd. Surrvma Theologica, I, QQ. 84, 85; Vd. also Q. 79, A. S.
The mode of the intellect in understanding is different from the mode of
the thing in its essence" (Summa Theologica, I, l!l,
ad 3); "In these words
the thing actually understood there is a double implication-the things which is
understood and the fact that it is understood. In like manner the words abstract
universal imply two things, the nature of a, thing and its abstraction or universality.
Therefore the nature itself to which it occurs to be understood,
abstracted or considered as universal, is only in individuals; but it is understood,
abstracted or considered as universal, as it is in the intellect " (ibid., 85, 2, ad 2) .
40 "

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The implications of this analysis for our present discussion are
drawn by St. Thomas in his consideration of communicable names:
A name is communicable in two ways, properly and by similitude. It is
properly communicable in the sense that its whole signification can be
given to many .... For instance, this name lion is properly communicated
to all things of the same nature as lion . ... To know, however, what names
are properly communicable, we must consider that every form existing in
the singular subject, in which it is individual, is common to many either
in reality, or in idea; as human nature is common to many in reality,
whereas the nature of the sun is not common to many in reality, but only
in idea; for the nature of the sun can be understood as existing in many
subjects; and the reason is because the min(i understands the nature of
every species by abstraction from the singular. Hence to be in one singular
subject or in many is outside the nature of the species. So, given the idea
of a species, it can be understood as existing in many. 41

The words we shall use to name the specific and generic natures of
existing individual substances are properly communicable; and the
natures thus named are common to many in reality, and not merely
in idea. The understanding of this point is sufficient for our purposes, even though the metaphysical problem of the one and many
remains undiscussed. The profoundly difficult metaphysical task
of explaining the unity of the nature which is common to many in
reality need not be discharged as a condition precedent to the
resolution of the problem of species (i. e., specific natures), as that
occurs in the philosophy of nature. Suffice it if we realize that the
unity of the nature in reality, as common to many individuals
(and through this community being a single intelligible object)
is not the same as the unity of the nature in idea, as actually understood, the idea itself being reflexively understood as a single
abstract universal, capable in its singleness of functioning as the
medium whereby we know one and the same nature existing in
many individuals.<l2
Thus, critical realism, holding that things are not as we know them, avoids the
error of naive realism, holding that things are exactly as we know them; but it
also avoids the error of subjectivism (which says that we cannot know how
things are in distinction from the way they appear to us as known) , by showing
how the mind transcends itself by understanding its own operations; through this
reflexive understanding we are able to know the difference between the way things
exist in themselves and the way they appear to us as known. The fact of reflexivity
also makes the objective concept, itself an actual universal, not only something
understood, but something understandable, for it is the intelligible object of second
intentional knowledge.
41 Summa Theologica, I, Ill, 9.
•• " The universal can be considered in two ways," St. Thomas tells us. " First,
the universal may be considered together with the intention of universality. And

9

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MORTIMER J. ADLER

I need not go further into the analysis of a concept's relation to
its object. These matters have been adequally treated in many
good contemporary discussions. 48 My only purpose is raising these
questions at all was to make four points explicit: (I) that the
doctrine of moderate realism is indispensable as a framework in
which to carry on the discussion of species and specific natures;
(2) that some community of natures (specific or generic) must exist
in the plurality of existing individuals for our concepts (specific or
generic) to enter into true universal judgments about reality; (3)
that this can be so in spite of the fact that the common nature as
really existing is not actually universal, and in spite of the fact that
the unity of what is common to many in reality is not the same as
the unity of the idea whereby that common nature is known; (4)
that these things must remain true for whatever metaphysical account is given of the unity of the nature that is common to many
in reality .44
since the intention of universality, viz., the relation of the one to the many, is
due to the intellectual abstraction, the universal thus considered is a secondary
consideration. . . . Secondly, the universal can be considered in the nature itselffor instance, animality or humanity as existing in the individual" (Summa Thoologica, I, 85, 3, ad 1). The so-called logical universal is thus seen to be a second
intention, whereas the so-called metaphysical universal is a first intention. It is
through the concept functioning as a first intention, as a metaphysical universal,
that we apprehend the same nature in many individuals having the same nature.
By means of the concept, functioning as a second intention, as a logical universal, we apprehend the unity of the idea itself.
•• Vd. op. cit., in fn. 33 au.pra; vd. also Fr. Gerard Smith, "The Concept in St.
Thomas" in The New Scholasticism, March, 1938: pp. 52-56.
.. I would like, in addition, to suggest two things. First, that many individual
things (the ultimate material objects, the absolute id quod of knowledge) become
one object when, in the process of being known, they are known through one
formal concept (the id quo) and known as one objective concept (the medium
quod and the quid of knowledge) . That many things in existence can become
objectified, in being known, as one object of knowledge, indicates that the unity
of the nature-as-known (the objective concept) is not the same as the unity of
the nature-to-be known, which is one and the same nature-to-be-known in the
many things. It would appear that what is potentially one (the nature-to-beknown) in an existent plurality of things, becomes actually one (the nature-asknown) when that plurality is unified under a single objective concept. (The
essence or res which, considered absolutely, is neither singular nor universal, is
one as it exercises intentional existence, actually universalized; and it is many
as it exercises real existence, potentially universal.) The objectification of the
thing (res) is thus an actualization of the potential universal, simultaneous with
the actualization of the intellect. And, thus, the intelligible in act becomes one
with the intellect in act. Secondly, that the unity of a nature as existing in
many individuals is an analogical, not a univocal, unity of being, even though
the concept whereby that nature is apprehended is primarily a univocal and not
an analogical concept. This must be so, for there is no way in which the one

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The understanding of these four points should protect the following
discussion from being misunderstood, and should prevent needless
excursions into irrelevant matters. I hope this whole section devoted
to preliminary clarifications frees the reader from other concerns,
so that he can focus on the matters at hand. I have learned from the
discussion of The Problem of Species how much that is a consummation devoutly to be wished.
III.

REFORMULATION

OF THE ISSUE

8. As I have already pointed out,4.4 a the issue between the first
theory (concerning species and specific natures) and the second
theory was a false one, as I set it forth in The Problem of Species,
because of an error in my exposition of the first theory. In order,
therefore, to rectify the issue i:t,Pelf, prior to resolving it, I shall
proceed, first, to indicate the origin of the error; second, to correct
the error, thereby-showing it to be accidental, not essential, to the
principles of the first theory; and third, to summarize the resultant
opposition between the second theory and the first theory as
rectified.
9. The basic insight which generates the first theory is its vision
of an ontological hierarchy-a hierarchy of corporeal substances
which resembles the hierarchy of separate substances. Just as no
two angels are, as individually existing species, equal in grade of
being, so no two composite substances are equal in grade of being,
if diverse in specific nature. Just as each angel has a substantial
perfection lacked by its proximate inferior and lacks a substantial
perfection possessed by its proximate superior, so each substance
of a given specific nature has an essential perfection lacked by its
proximate inferior in specific nature, and lacks an essential perfection possessed by its proximate superior in specific nature. To
call this type of hierarchy perfect is to say that it is a perfectly
ordered series, in which each member has a unique position, in
which there is no coordination or equality of rank, in which each
member comes before or after another in the ascending or descen<Ling scale of being. This vision of a perfect hierarchy is contained in
the passage in which Aristotle compares the order of essential definitions to the series of whole numbers; and also, in another context,
in the passage which compares the order of souls or substantial
forms to the series of regular plane fil!ures.4 G
can exist in the many except analogically. I shall return to this point in a later
discussion of the analogical note in univocal concepts of species and genera.
••• Vd. Part I supra..
•• These two passages and the capital texts on which the first theory rests its

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This basic insight is further developed by the analysis of the way
in which each member of a perfect hierarchy includes aU of its
inferiors, and is included by all of its superiors. Confining our
attention now to the hierarchy of corporeal substances, we learn.
from the analysis of human nature, the supreme nature in that
hierarchy, how the human soul virtually includes not only all
inferior souls, but all inferior substantial forms. 46 Because the
human soul virtually includes all inferior souls and forms, human
nature actually possesses every essential perfection belonging to
inferior natures, and in addition possesses an essential perfection
which none of these possesses. The hierarchy of specific natures is
thus exhibited within human nature itself-in the hierarchy of
virtually included forms, in the hierarchy of the actually possessed
essential perfections, signified to u.s by the hierarchy of man's
powers or proper accidents. What is here seen to be the structure
of human nature holds similarly for every inferior specific nature:
in each case, the actual specific nature of a substance virtually
includes all inferior natures, and actually possesses all their essential perfections, excelling them, in each case, by possessing an
essential perfection lacked by aU its inferiors. The hierarchy of
corporeal substances can thus be looked at in a number of ways:
as a hierarchy of specific natures actually existing in individual
things; as a hierarchy of virtually included forms contained in and
excelled loy human nature as the supreme member of the hierarchy;
as a hierarchy of essential perfections actually possessed by man,
and signified by his powers as these are hierarchically orderedY
The principle of perfect hierarchy is the source of all the remaining points in the first theory: it is responsible for the first theory's
answer to the question about the number of specifically distinct
natures; it is responsible for the first theory's account of specific
differentiation; and, accidentally. it was responsible for the erroneous notion about generic natures, now to be corrected. Waiving
for the moment the question about number, let me explain how the
error came about.
case. The first passage is in the Me::taphysics, VIII, 3, 1044• 10; the second is in
De Anima, II, 3, 414b 20-31. For the many Thomistic commentaries on these
passages, vd. the citations in The Problem of Species, pp. 52-60; THE THOMIST,
I, 238-46.
•o Vd. Summa Theologica, I, QQ. 75 and 76. Vd. Problems of Species, pp.
54-60; THE THOMIST, I, 240-46, for a complete citation of Aristoteliall and
Thomistic texts.
47 It is interesting
to discover all these traits of a perfect hierarchy in the series
of whole numbers or the series of regular plane figures. Aristotle develops the
comparison explicitly.

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However many specific natures there are, the principle of hierarchy requires that the number of essenti;'!l perfections which can
be possessed or lacked must be the same as the number of natures
specifically distinct; for in every case, a given specific nature posand in addition
sesses all the essential perfections of all its
possesses one more, by reason of which it both differs specifically
from its proximate inferior, and excels it. Hence it would appear
that, between two natures, proximately related as specifically distinct from one another, there is only one essential perfection as a
source of difference, that one perfection being lacked by the inferior
and possessed by the superior. 48 The foregoing statement is true,
but it is not the whole truth, and from the failure to observe that
fact my error followed. There is truth in this statement only in so
far as we look at the two natures being considered from the point
of view of the superior; for it does positively differ from its inferior
by possessing an essential perfection which the other lacks. But
we cannot define the inferior nature in terms of what it lacks, in
terms of mere privation; nor can we avoid this difficulty by saying
that we can only define the inferior nature by treating it, in turn,
as a superior differing from and excelling a third nature by possessing an essential perfection that third nature lacks. Our philosophical principles of differentiation and definition must hold true
even for the hypothetical situation of only two specific natures in
the corporeal order; in which case, the inferior could not be treated
as a superior, and it would be impossible, therefore, to give an
intelligible account of this nature: it could not be defined merely
in terms of a perfection it lacked. Mere privation cannot be. the
principle of the difference in a determinate nature; and a specific
nature must be essentially determinate. 411
Seeing only half the truth:. I made an error which had the virtue
•• In this respect, the corporeal hierarchy would also appear to resemble the
spiritual hierarchy, for St. Thomas tells us that, in the case of intellectual substances, division into species is not accomplished by two true differences. Vd.
De Ente et Essentia, Ch. V. In other words, between two such species, proximately related as inferior and superior, there is only one substantial perfection,
possessed by the superior, and lacked by the inferior, as a principle of difference.
•• The error I have just called attention to not onJy generated the error about
a common genus, which I have already mentioned; it also created what looked
like an insuperable difficulty in the first theory, namely, the unintelligibility, more
than that, the intrinsic impossibility of the lowest or least perfect· member of a
hierarchy of specific natures. Vd. the seventh objection against the first position
THE THOMIST, II, 145-47. At
in The Problem of Species, Ch. VIII, pp.
the time I found it unanswerable. But now that I can correct the error about a
common genus, I can also completely answer that seventh objection, and thus
free the first position from any intrinsic difficulty.

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MORTIMER J. ADLER

of being consistent with the half-truth I saw. I denied that two
specific natures (proximately related as superior and inferior, and
apparently separated by only one difference, the essential perfection
lacked and possessed) could have a generic nature in common; or,
to put it another way, I said that two substances, specifically
distinct and hierarchically proximate, could not have one and the
same generic nature. To have said anything else would have been
to violate the half-truth of the principle of hierarchy-the halftruth which, at the time, I thought was the whole. Though I denied
a common generic nature, I could not entirely give up the notion of
generic nature. So, developing my error consistently, I said that
each inferior specific nature was identical with the generic nature
of its proximate superior; and that the additional perfection which
the superior possessed was the principle of the difference which,
penetrating and further determining the generic nature, constituted
that superior's whole specific nature. I sought to explain this by
saying that one and the same nature could be regarded in two ways:
as actually existing in the inferior substance, and as virtually
included in the actual nature of the superior substance. Regarded
in the first way, that nature was specific; regarded in the second
way, that nature was the generic constituent of the superior specific
nature. There is, therefore, no common generic nature, because
each specific nature has its own, and quite unique, generic nature,
namely, the specific nature of its proximate inferior as that is
virtually included in its own essence.
A little error in the beginning has serious consequences in the
end-particularly if one develops it relentlessly and adheres firmly
to its implications. No one could want a better illustration of this
Thomistic maxim than the case at hand. For I was led on by my
own thinking to two absurdities: (I) I found myself compelled to
say that there was a fundamental discrepancy between the order
of natures and the order of concepts; for it could not be denied that
in the logical hierarchy species do participate in a· common genus,
whereas I thought I had succeeded in denying the occurrence of
any common generic natures in the ontological hierarchy. I could
not deny that the concept animal was commonly predicable as a
genus of both man and cow, or man and brute; I could avoid the
implications of this mode of predication only by saying that the
word " animal" thus used signified a logical genus, whereas the
ontological genus (i. e., generic nature) of man was signified by
the word" brute "-the same word which signified a specific nature,
in fact the specific nature of cow. Hence, I had to deny, at least
implicitly, that the ordinary modes of predication followed the real

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modes of being; and I had to embrace the notion of a single concept,
such as brute, which could be predicated in diverse manners, now
as the genus of man, now as the species of cow (cow signifying a
race of brute); (2) I found myself unable to account for the
duplicity of the concept brute, for it seemed to take on the meaning
of animal when, taken as signifying a generic nature, it was predicated as the genus of man, and it seemed to diverge somehow from the
meaning of animal when, taken as signifying a specific nature, it
was predicated as the species of cow. Certainly one could not define
a man as a rational brute.
I refer to these consequences as absurdities. They are that, in
the light of Thomistic principles. But, at the time, blinded by the
half truth I saw too clearly, I did not see them that way. The truth
in the principle of hierarchy seemed worth sticking to-in spite
of these difficulties, some of which I recognized at the time, but
naturally treated only as apparent (hence curable) difficulties, not
as real absurdities:'50 The principle of hierarchy was worth sticking
to, for when its whole truth is grasped, it not only makes the first
theory entirely sound, but also shows why the second theory is untenable. That whole truth is grasped when we see why hierarchy
does not require the denial of a common generic nature; or, to put it
positively, when we achieve an analysis of genus and difference that
is in every way compatible with perfect hierarchy, as it obtains in
both the real and the logical orders without any discrepancies
between them.
10. For the sake of brevity, I shall confine my discussion to three
terms: animal, man, and brute; for if it can be shown in this
one case how animal is the common genus of man and brute
(regarding these two as infima species proximately related as superior and inferior, and between which there appears to be only one
positive difference, the perfection rational, possessed and lacked
then the theory of the common genus and of differentiation, thus discovered, will apply to any similar set of terms.
What is here said in the language of logic (considering concepts)
can, of course, be also said in the language of ontology (considering
natures). The logical account of a common genus, compatible with
the principle of hierarchy, and the ontological account of a common
generic nature, similarly compatible, must conform to one another.
It will be further noted that I referred to man and brute as infima
species, by which I mean that each is to be regarded as the concept
of a fully determinate specific nature; neither is to be regarded as
capable of any further essential differentiations. The reader must
50

Vd. fn. 6 and 9 rupra.

312

MORTIMER

J. ADLER

understand that, in doing this, I am not begging the question of
the rightness of the first theory, which insists against the second
that brute is a species, not a genus. At this point I am merely
trying to show how the first theory can be rectified, by retaining its
principle of hierarchy and rejecting its denial of a common generic
nature. The proof of the rightness of the first theory, thus rectified,
will come later.
The formal conditions of a solution are as follows: the genus
must be indeterminate in the several respects in which its species
are determinate; the genus must not only be indeterminate in these
respects (i. e., in privation) but it must also be determinable; and.
the constitution of the several species is by the determination of
the genus in the diverse respects in which it is determinable-the
formal cause of this determination being, in each case, the difference.
So it would appear that if there are to be two species sharing in a
common genus, each determining it differently, there would also
have to be two differences; each of the two species being thus
constituted by the same genus and its own difference.
Now these formal conditions are readily satisfied by many sets
of three terms, as, for example, taking animal as genus, and
herbivorous animal and carnivorous animal as species. 51 For here
the genus is indeterminate with respect to two modes of vegetative
activity; here there are two positive differences which diversely
determine the genus in the respects in which it is determinable.
For the sake of generality, let us symbolize this situation by letting
G represent the genus, and d 1 and d 2 the two differences; 8 1 and
8 2 (the two species) are then defined as G:d 1 and G:d 2 •
But it will be seen at once that these conditions are not so readily
satisfied by the set of three terms, animal, man, brute; and the
reason is also apparent. Herbivorous animal has a perfection which
carnivorous animal lacks; and conversely, the carnivore has a
perfection which the herbivore lacks. But man lacks no perfection
possessed by brute, whereas brute lacks a perfection possessed by
man. The relation between carnivore and herbivore as species
violates the principle of hierarchy. 52 Hence we must conclude that
51 Vd. Aristotle,
Historia
I; De Partibus Animalium, I, 3. Cf.
Anal. Post., II, 13; Topics, VI, 6.
52 Therefore,
from the point of view of the first theory, adhering to the principle of hierarchy, they cannot be regarded as genuine or proper species. It makes
no difference, therefore, whether the second theory regard carnivore and herbivore
as sub-genera of animal or as infima species; nor does it make any difference to
the present argument that there may be a third coordinate species, omnivorous
animal. The only point being made here is that according to the first theory,
herbivorous, carnivorous, and omnivorous cannot be essential perfections, because

SOLUTION OF THE PROBLEM OF SPECIES

818

if the symbols G: d 1 and G :d2 represent the only way in which two
species can have a common genus, then a common genus is absolutely incompatible with the principle of hierarchy.
That conclusion can be avoided. There is nothing wrong with
the formal conditions to be met; and they can be satisfied by the
terms animal, man, brute; but not in the same way as by animal,
herbivore, carnivore. The analysis is as follows. The genus animal
is indeterminate with respect to the one essential perfection rational,
but in two ways. It is indeterminate because the sensitive nature
conceived as animal is conceived as in privation of rationality. But
that one perfection can either be possessed or rejected. The rejection of rationality is not the same as the privation of it: the
negative is not the same as the privative. Hence, in privation of
rationality, animal is both potentially rational and potentially
irrational: rational here signifies a positive difference, and irrational
a negative difference; and we must use the word " non-rational "
to signify the privative state of animal, conceived as determinable
in two ways with respect to one and the same essential perfection,
namely, by the determination of a positive and of a negative difference. Again, for the sake of generality, let us symbolize this
situation by letting G represent the genus; let the letter "x " stand
for the one essential perfection possessed by the superior species and
lacked by its proximate inferior; but since that inferior does not
merely lack the perfection in question (for then it would not differ
from the genus which is in privation with respect to this perfection),
but rather positively rejects or excludes this perfection, let us
symbolize the difference which, with the genus, constitutes the
superior species by dx, and the difference which, with the same
genus, constitutes the inferior species by d (x) . Thus, man is defined
as rational animal, G: dx; and brute is defined as irrational animal,
G:d(x) .52 "
A comparison of the two theories of genus and difference shows
the following fundamental points of divergence between them. (I)
they are not ordered hierarchically; and hence they cannot be the principles of
essential differentiation.
••• I am here using the symbols G: dx and G: d (x) with absolute generality,
despite the fact that I have exemplified their signification by such terms as
man, and brute. G stands for any genus, not just for animal, x stands for any
essential perfection, not just for rational, dx and d (x) stand for any pair of positive
and negative differences (determinations rooted in the same perfection), and hence
G: dx and G: d (x) stand for any species in a common genus, not just man and
brute.. I shall subsequently, in Diagram 1 and in the accompanying text, use these
symbols, G and x, with more restricted meanings, but the principle of symbolization
will remain the same.

314

MORTIMER J. ADLER

In the one case, the genus is in privation with respect to only one
perfection and must therefore by symbolized by G-x (where -x
represents the privation of x) ; in the other case, the genus is in
privation with respect to two (or rnore) perfections, and must therefore be symbolized by G-1,-2. (2) In the one case, the diverse
differences, diversely determining the genus to constitute different
species, are always related as positive and negative with respect
to one and the same perfection, and as possessing or rejecting that
perfection must be symbolized by dx and d (x); whereas, in the
other case, the diverse differences are always both positive, because
each is a difference arising from the possession of a distinct perfection, and hence must be symbolized by d1 and d 2 • Despite these
crucial divergences, both theories satisfy the same formal conditions,
namely, a genus indeterminate and determinable in diverse ways;
and a diversity of differences, neither of which is a mere privation.
Let us name these two theories of genus and difference, for the
sake of brevity of reference. Let us call the theory which is
symbolized by G-x, dx, and d (x), the first theory, because it is the
only theory of genus and difference which is compatible with the
principle of perfect hierarchy, and hence it is the theory of genus
and difference which must be held by the first theory of species.
Let us call the theory which is symbolized by G-1,-2, and d 1 , and d 2 ,
the second theory, because it is the theory which is absolutely
incompatible with the principle of perfect hierarchy, and hence it is
a theory of genus and difference which must be held by the second
theory of species, to whatever extent that second theory denies the
principle of perfect hierarchy. 58 And we can summarize what we
have learned so far by saying that if the only account which could
be given of genus and difference were that offered by the second
theory, then the first theory of species, adhering to the principle of
hierarchy, would have to reject the notion of a common genus and
diverse differences; and it would be right in doing so, because such
notions are absolutely incompatible with its own fundamental
principle. Fortunately, indeed, the notion of a common genus and
diverse differences need not be denied in order to affirm a perfect
hierarchy of species, for there is, we now see, a theory of genus and
difference, thoroughly compatible with hierarchy, which explains the
•• What I have here called the first and the second theory of genus and difference, I shall later call, respectively, the theory of the essential genus and of
essential differentiation, and the theory of the accidental genus and of accidental
differentiation. This manner of speaking will be justified when I show that the
second analysis belongs to a theory of "accidental species "-races, sub-species,
accidental concretions-or what Maritain has called improper species. Cf. fn. 98

infra.

SOLUTION OF THE PROBLEM OF SPECIES

815

commonness of the genus, and the diversity of the differences, in
the case of two species differing inter se with respect to only one
essential perfection, possessed by the one, and rejected by the other.
Thus is the first theory of species completely rectified in the line of
its own analytic tendency. 54
To expound this rectification fully, three more points must be
made. (1) There may be some who do not see the significance of
the first theory .of genus and of difference. For them let me propose
an analogy which will express that theory in the basic metaphysical
terms of potency and act. The human intellect is in potency to the
truth. As in pure potency, the intellect is conceivable as in privation
with respect to the truth. But, as in potency (and privation), the
intellect is determinable with respect to this one perfection (truth)
in two ways: it can be determined by knowledge and by error.
When it is actualized by the possession of the truth, it has knowledge; when it is actualized by the rejection of the truth, it is in
error. And we speak of the mere privation of truth as ignorance.
Although error is like ignorance in one respect (privation of truth),
it is unlike ignorance in another, for error is an actual negative
condition, a rejection of the truth, whereas ignorance is merely a
privative condition of non-possession. And error is just as much an
act of the intellect (albeit a vicious one) as knowledge is, for both
involve the intellect in judging of what is and what is not, whereas
ignorance which is a privation has no actual existence at all in the
· •• The half truth I saw in the principle of hierarchy is now enlarged into the
whole truth. It is true that between two species, proximately related, there
is differentially only one essential perfection. It is true also that that one
perfection is possessed by the superior and lacked by the inferior (and that the
superior lacks no perfection possessed by the inferior). But that one perfection
is the root of two determinations of the genus which is a nature conceived as
simply in privation with respect to that perfection: the two determinations are
related as positive and negative, i. e., positive, the possession of the perfection;
negative, the rejection or exclusion of the perfection. Hence there are two differences, not one; for each real determination of the genus, in a respect in which
it is indeterminate, is a difference. If we use the words " true difference " to
name the positive determination, then, of course, we must say that there is only
one true difference between two proximately related species; but clearly that is
a wrong manner of speech, for the negative determination is just as truly a difference as the positive. Hence, we must say that there cannot be two positive
differences between two species proximately related, for there is only perfection
as the root of their differences, that one perfection being the source of both a
positive and a negative difference. The reason for my error is now obvious: it
arose from confusing rational as signifying the perfection with rational as signifying the positive difference; and from confusing irrational as signifying the negative difference with non-rational as signifying the privation of the perfection which
makes the genus animal doubly indeterminate and doubly determinable by both
rational and irrational as true differences.

316

MORTIMER J. ADLER

order of the real. The potency and privation of the genus animal
is like the potency and privation of the intellect in a state of
ignorance; the perfection rational is like the perfection truth, for
it is with regard to these perfections that animal and intellect are,
respectively, in privation: animal is non-rational (non-possession
of rational),. the intellect is ignorant (non-possession. of truth);
rational and irrational as positive an:d negative. differences, are
diverse determinations or actualizations of a double potentiality
in animal, just as knowledge and error are, as positive and negative
states of mind (intellectual virtue and vice), diverse determinations or actualizations of a double potentiality in the intellect; and
in both cases the diverse positive and negative determinations are
with respect to one and the same perfection. 55
There is no longer any problem about the predicability of
the genus animal of such diverse species as brute and man. It is
hot only predicable of them both, but predicable commonly, as a
genus, and in the same way, as their proximate genus. Nor is there
any difficulty about the case in which we predicate animal of both
man and cow, although it is necessary to observe that this case is
not identical with the previous one. For, according to the first
theory of species, cow is not properly a specific concept: cow
signifies a race, an accidental subclass of the species brute. Hence,
when we conceive the specific nature of cow by the concept brute,
animal is predicable of both cow and man, commonly as a genus,
but not in the same way, for cow is not a species of animal, nor
even a species of brute; hence animal is the genus of cow only by
11 It may be asked in what way the intellect knowing includes and excels the
perfection possessed by the intellect erring, as man includes and excels the perfection possessed by brute.. The analogy here is not perfect because there is no
third term related to the intellect erring as an inferior species (plant, let us say)
is related to brute. But the analogy is not altogether imperfect, because the
intellect knowing includes the quasi-perfection of the intellect erring: for there
is no absolute error; and in so far as all error contains some element of the truth,
the intellect erring is more determinate with respect to truth than the ignorant
intellect; furthermore, he who knows not only knows what is true, but what is
false, and in this the state of knowledge includes and excels the state of error,
transforming it, of course, in including it, just as the rational nature includes the
sensitive perfection eminenter, not simply.
I have thus explained what is logically conceived as privation, negation, and
possession, in terms of potency and act. Such explanation is necessary to give
the logical account of genus and difference metaphysical meaning, for in the order
of the real there are no privative or negative beings. I shall later give another
metaphysical rendering of this analysis in terms of matter and form, again translating negation and privation into metaphysical terms. See Part V, Section
15, (2), infra.

817

SOLUTION OF THE PROBLEM OF SPECIES

DIAGRAM 1
DEFINITION

SPECIES

GENUS

!n s.

DEFINITION
Ga: dx

•

l
·:

,,
Ga aninud

G 2 : dy
-x

l

(sensitive nature)

G1: dz
-y,-x

G,

.

living thing

,,
,..-

.....
....
....
,...,....

G:·w
-z,-y,-x

G1 dimensive thing .........

:!

s.

G,: d(x)

s.

G.: d(y)

s1

G1: d(z)

Ii
:

:
:

I

(corporeal nature)

Legtmd: dx and d(x) signify possession and rejection of perfection x (rational)
dy and d(y) signify possession and rejection of perfection y (sensitive)
dz and d(z) signify possession and rejection of perfection z (vegetative)
- x, - y, - z signify the privation of the perfections x, y, and z.
w signifies the ultimate generic perfection (corpdTeal)
G signifies the genus substance

Note: The ultimate generic perfection w is never the root of a difference, positive or negative,
for it is possessed by every species. Because w is not the root of any difference, G:t
is not defined by G: dw, but simply by the perfection w itself as a first determination
of the summum genus substance. In each case, the genus is, in the vertical axis, on a
lower level than its negatively determined species, to indicate that that species is
superior in degree of detenninaay, even though not superior in grade of perfection
possessed.

318

MORTIMER J. ADLER

virtue of what is properly the species to which cow belongs as one
of its :races, namely, brute. Yet it can be said that animal signifies
the generic nature which is both common and proximate to the
specific natures of man and cow, even though cow itself does not
properly signify a specific nature, for it signifies a specific nature
(conceived as brute) under a certain mode of further accidental
determination.
(3) Thus, we see that the first theory of species (rectified by a
theory of genus and of difference compatible with the principle of
hierarchy) can affirm, without qualification, that modes of predication perfectly follow modes of being. That being so, there must
be a perfect parallelism between a logical hierarchy of concepts,
arranged according to their formal properties as proper species and
genera, and an ontological hierarchy of natures, in which the disposition of natures as specific and generic is seen. To show this,
I shall diagram a hierarchy as that is conceived according to the
first theory. The members of this diagram will be equally interpretable in logical and ontological terms. In setting up this diagram,
I will proceed on the hypothesis, to be proved, that there are only
four proper species (in the logical order) and only four specific
natures (in the real order of corporeal substances) .
.In interpreting this diagram it is important not to be disturbed
by the actual words which have to be used to name the various
members. Familiar words are available to name the four specific
members; but, except in the case of animal, there is no single word,
nor even always a familiar and entirely satisfactory phrase, to name
the generic members-if one wishes to avoid duplicating the same
word as the name for a specific and generic member.
Let me explicate the diagram, for by doing so I can give a summary account of the first theory of species, genus, and difference.
(I shall speak the language of logic in doing this.) (1) On the
hypothesis of four species, there are only three genera; but there
are six differences, since there are three essential perfections each
of which can function as the root of two differences, a positive and
a negative. There is, of course, a fourth essential perfection, W,
the lowest in rank, which is the only source of determination in the
most indeterminate genus, G1. (2) Except for the highest species,
each species is determined by a negative difference, the perfections
it possesses accruing to it from the fact that its proximate genus is
determined by a positive difference; thus, for example, brute is irrational, d (x), but it is also animal, G 3 , and as animal it is sensitive,
dy; further, since the genus animal includes the remote genera, G2
and G1, brute not only possesses the perfection y, but also the

SOLUTION OF THE PROBLEM OF SPECIES

819

perfections z and w. Each of these species is, therefore, seen to
possess all the perfections possessed by its inferiors, to possess in
addition one perfection they lack, and to be determined in its
unique nature by rejecting the perfection possessed by its proximate
superior. (3) Each of the genera is at once the proximate genus of
a species and the remote genus of that species' proximate superior,
through being a genus of that superior's proximate genus; here, too,
there is an exception, for the genus animal, which is highest in the
hierarchical order of perfections, is at once the proximate genus of
two species. (4) Like the order of species, the order of genera
is a hierarchical order of ascending degrees of perfection: in which
the lowest genus signifies the least degree of perfection (w), and
each higher genus signifies more perfection and less privation.
This is indicated by the use of -x in the definition of Ga, of -y, -x
in definition of G2 ; and of -z, -y, -x, in the definition of G1 • Viewed
positively, G1 has the perfection w, which is here simply a principle
of determination and not of difference; G2 , the positive difference
whose root is perfection z, and G 3 the positive difference whose root
is perfection y, as well as, of course, perfection z because Ga includes
G 2 • (5) The complete definition of the genera must include privative notes; whereas the definition of the species includes only a
positive note (possession of perfections) on the part of its genus,
and a negative note (rejection of a perfection) on the part of its
difference. Again, there is an exception in the case of man, the
highest species, constituted by two positive notes, on the part of
both its genus and its difference. (6) Only the two highest species
have a genus which is both common and proximate; in every other
case, considering a pair of proximately related species such as brute
and plant, the proximate genus of the' lower is always the remote
genus of the higher, remote by one remove; and, by extension of
this principle, the proximate genus of the lowest species is necessarily the remote genus of the highest by two removes. (7) There
is no genus which is the common and proximate genus of two other
genera; the only genus which is a genus of two other genera is the
lowest genus and this is the proximate genus of G 2 and a remote
genus of Ga. (8) In the case of animal, man and brute, the genus
resembles the lower of its two proximate species more than the
higher, in the sense that it is privative with respect to the same
perfection, with respect to which the species is negatively determined; in the case of every other genus, the genus similarly resembles its proximate species more than it does the proximate
higher genus. This is indicated by the use of dotted lines in the
diagram to indicate the motion of a genus toward the negatively

320

MORTIMER J. ADLER

determined member. (9) In the hierarchy of species, the lowest an<!
the highest are each unique, but not in the same way, for in the case
of the highest species, its special perfection is signified by a positive
difference, whereas in the case of the lowest species, its only perfection, signified by the respect in which its genus is determinate, is
not the root of a negative difference.
These nine foregoing points formulate the doctrine of a logical
hierarchy of species and genera. The one indispensable hypothesis
underlying this formulation is the principle of hierarchy itself, as an
order in which each member has a higher or lower grade of perfection. It should be added, of course, that only concepts which are
proper species and proper genera (i. e., concepts of truly specific
and truly generic natures) can be so ordered. That four should be
the number of species is not an indispensable hypothesis for working
out of the doctrine of hierarchy itself; the number might be smaller
or greater, and it would be possible for all of the same principles
to obtain. But what is possible need not be actual; that there are
only four proper species is a point of actual fact, to be discussed
later.
It is unnecessary to repeat these nine points of doctrine in the
language of ontology: everything which has been said in terms of
species and genera (specific and generic concepts) can be restated,
without a single discrepancy, in terms of natures, specific and
generic. 56 What is necessary, however, to complete this exposition
is to diagram the radically different view of hierarchy which is
involved in the second theory of species, genus, and difference. The
contrast between these two views will help us to formulate the issue
as sharply as possible. Here, as before, I shall present a diagram
which is capable of being interpreted in ontological as well as in
logical terms. In setting up this diagram, I will proceed on the
hypothesis, to be disproved, that there are many more than four
proper species, and I shall signalize this point by treating brute
•• Vd. fn. 55 supra. There is a tenth point of doctrine which is, however, purely
logical. It arises from a consideration of the members of the logical hierarchy in
terms of their extension and comprehension as concepts. The genera, of course,
have greater extension and less comprehension than any of the species, and the
lowest genus has the greatest extension and the least comprehension. But the
species considered among themselves cannot be compared with respect to comprehension and extension, for they are all equally determinate as concepts, each
definable as an infima species. It should be noted, of course, that this doctrine
can dispense with the qualification infima, for every concept which is properly a
species is an infima species in the sense that it is that whereby a specific nature
is conceived; and there is no need to regard a genus as a non-infima species because
it mediates between a species and its remote genera.

SOLUTION

821

OF THE PROBLEM OF SPECIES

DIAGRAM 2
GENERA

GENERA

GENERA

SPECIES

r---------------------------------man

DEFINITION

Sn= Ga: dx

s"' = An.c.D.: dk
G.

animal

GA
brute
(Sa)

a.

living
thing

s,- AB.c.D.: df
(S.)

Legend: GA: brute, sub -genus of animal, defined here as S. is in Diagram 1.
'8n: man, highest infima species of animal, defined here as 8 4 is in Diagram 1.
AB, .... ABn: sub-genera of brute, each determined by a positive difference, signified by the
numbers from 1 to n.
sub-genera of the sub-genera on the B level, each sinlilarly deter{ AB1 C. .... AB1
ABnC. .... ABnCn
mined by a positive difference.

C..}

AB.OtD, ... AB10tD,.}
sub-genera of the sub-genera on the C level, each sinlilarly de{ AB1 CnD 1 ... AB1 CnD,.
ABnC.D1 ... ABnC 2 D,.
termined by a positive difference.
ABnCnD, . . . ABnCnD,.
{ Be, Sr 1 infima species, having their proxinlate genera on the D level of the hierarchy, each
SA, S• S
determined by a positive diffllrence, signified respectively by de, df, dh, and dk.

Note: The numbers and letters here used must not be taken as symbolizing an exhaustive enumeration
of the sub-divisions within the genus brute. They are used to signify only the multiplicity of
the divisions of sub-genera into sub-genera and ultinlately into infima species. It will be noted
that not all the sub-genera are divided, nor are all possible divisions carried
in order to
prevent too great a complexity in the diagram.
In the definition of each of the four infima
species, inferior to
the last difference is added to a summation of the generic determinations
by which the ultinlate genus being divided, brute, is contracted in the direction of that species.
The dotted lines in the vertical axis of the several columns of the diagram (generic and specific)
are intended to signify intermediates between the terms which have been indicated.
They are
not intended to signify an order from lower to higher in the scale of being, for that may or
may not be the case.

10

322

MORTIMER J. ADLER

as a genus capable of differentiation into sub-genera and ultimately
into proper species. 56 "
I need not bother to state all of the characteristics of the hierarchy of terms set forth in Diagram 2. They are familiar points
learned in elementary logic courses. I wish only to comment on
Diagram 2 in relation to Diagram 1. (I) In the first place, it should
be noted that I have included a part of Diagram 1 in Diagram 2.
This is necessary, because the second theory must agree with the
first on two facts: namely, that man is a rational animal, and that
brute, defined as irrational animal, is the other member dividing
animal as the proximate genus. (2) What is here done for brute
could be similarly done for plant and body, regarding them as genera
rather than as species: in each of the latter cases, the type of
analysis made in Diagram 1 would be repeated; and in each case,
plant and body would be treated as genera, and subdivided into
sub-genera and ultimately into infirma species, exactly as is done
here in the case of brute. (3) Below brute all the divisions into
sub-genera and species result from positive determinations of the
genus in respects in which it is indeterminate and determinable:
because of this fact, a genus may always be divided into more than
two sub-genera or more than two species, whereas, in contrast,
genera which are determined by a positive and a negative difference
can never be subject to division into more than two species.
( 4) Within the genus animal, brute is hierarchically inferior to man;
but within the genus brute, the sub-genera may or may not be
hierarchically ordered; and so on down to any set of infima species
within their proximate genus-they may or may not be hierarchically ordered. Now there are these possibilities: (a) that all
of the species of brute taken together are hierarchically ordered as
inferior to man, by reason of their participation in the genus brute,
but that within the genus brute itself, there is no further hierarchical ordering; (b) that there is a hierarchical ordering among
the sub-genera of brute, at higher levels of generality, but not at
lower; (c) that there is a hierarchical ordering among the sub-genera
of brute even on the lowest level of generality, proximate to the
infima species; (d) that there is a hierarchical ordering, not only
among all the sub-genera of brute at each level of these sub-genera,
but also among each set of infima species dividing their proximate
genera.
It is only the various possibilities enumerated under the fourth
••• If we took the biologist's count of the number of species in the genus brute
would have to become an extremely complicated affair, repreanimal, Diagram
senting an orderly arrangement of
members.

SOLUTION OF THE PROBLEM OF SPECIES

39l3

point above which need concern us any further. I shall later show
why, as a matter of fact, only the first possibility can be actually
the case: because no set of terms which are constituted by diverse
positive differences, rooted in diverse perfections, can be hierarchically ordered as essentially higher and lower inter se. But
proceeding hypothetically, though contrary to fact, and even taking
the fourth possibility as the one which would realize to the greatest
degree the principal of hierarchy among the infima species of brute,
let me point out why the second theory, as represented in Diagram
2, denies the principle of perfect hierarchy. For according to this
theory, even though each of the infima species of brute can be
ordered as higher or lower than another in grade of being, all of
them, taken together, are equal in their inferiority to man, for they
all equally differ from man by being brute generically. The generic
nature that is common to every one of these species is conceived as
irrational animal, and hence they are all equally inferior to man,
whose specific nature excels theirs by the possession of the one
essential perfection which they all equally reject.
Proceeding on the hypothesis that cow ... spider .•. oyster ..•
worm signify truly specific natures (whether that is the case or not
makes no difference), we can see that a hierarchy of species, in which
the term man is treated as a species along with cow, spider, oyster,
worm, etc., is radically different from the hierarchy of species, in
which man is treated as a species along with brute, plant, and body.
We focus on the precise point of difference when we see that in
Diagram 2 there is a geneTic interruption between the highest of
brute species and man, an interruption which reduces all the brute
species to one hierarchical level with respect to man. (This generic
interruption is symbolized in Diagram 2 by the double line which
separates man from all the species of brute). That is why I have
called the hierarchy envisaged by the second theory an imperfect
hierarchy of species (subject to many generic interruptions and
levelings), whereas, in contrast, the hierarchy of species envisaged
by the first theory is perfect. 57
•• There are as many generic interruptions in the hierarchy of infima species
as there are different levels of sub-genera included under brute; for
in Diagram
if, on each level of sub-genera (symbolized in Diagram
by the letters B, C, and
D), there is a hierarchical ordering, then the terms which are hierarchically
ordered on a lower level will be equalized in rank by reason of the rank which their
genus has in relation to the rank of the genus of some other set of terms on the
next level. Thus, for example, all the terms enumerated as AB1 C1-ABIC.,
will be equal in their inferiority to the set of terms enumerated as ABnC1AB,.C,. if the proximate genera of these two sets of terms, AB 1 and AB.,. respectively, are themselves hierarchically ordered as lower and higher; and simi-

324

MORTIMER J. ADLER

Only one further point need be made, before we proceed to the
summary of the issue. It concerns the word " hierarchy " itself in
which, unfortunately, so!p.e ambiguity still remains. It will be seen,
by examining Diagram 1, that both the hierarchy of species and the
hierarchy of genera (both, by the way, perfect hierarchies) are
orderings of terms, signified as higher and lower by their disposition
above or below one another in the vertical axis of the diagram. 578
In sharp contrast, we find that, in Diagram 2, there is a hierarchy
of terms in the horizontal axis of the diagram, as well as in its vertical axis. In the horizontal axis, there are the various levels of
genera, sub-genera, down to infima species, and reading from left
to right we pass from more general concepts to less general concepts-the level of generality itself being determined by the same
degree of extension and a reciprocal degree of comprehension in all
the concepts on that level. 58 Here, then, is a third meaning of the
word " hierarchy " which must be distinguished in all subsequent
discussion. Let me enumerate the three meanings, and indicate
how I shall qualify the word " hierarchy " to give it a univocal
meaning in each usage: (1) by "perfect hierarchy" I shall mean
larly in every other case. In short, returning to the four possibilities enumerated
in the text under point " (4) ," the one which achieves a hierarchy among the
specific terms " (d)," sets up the most imperfect hierarchy of these terms, because
subject to the greatest number of generic interruptions; whereas the one which
fails most to achieve any hierarchy among the specific terms " (b)," sets up the
least imperfect hierarchy of these terms, because subject' to the fewest generic
interruptions. But it is also t'rue that in the latter case, there is no hierarchy at
all of the specific terms, but only of genera. This indicates an insuperable
difficulty in the second theory. There is one other cause of imperfection in a hierarchical disposition of terms. If manifold differentiae are employed, instead of
single differentia, two items may each be superior and inferior to the other in
diflerent respects. If one tries to order a set of items, which are distinguished
inter se by manifold differentiae, no single arrangement of them is possible. There
will be several different ways of ordering them as lower and higher in being,
according to the particular characteristics chosen. I call this the fact of multilinear,
in contrast to unilinear, ordering. A hierarchy is imperfect if it is subject to generic
inj1·a, wherein it will be seen that a
interruptions and multilinearity. Vd. fn.
hierarchy of accidental terms is necessarily imperfect in both these respects.
na It will be noted that each genus (except animal) is, in the vertical axis,
below the species to which it is connected by a broken line, as well as below the
higher genus, to which it is connected by an unbroken line. This is done to indicate that each genus (except animal) is, on the one hand, inferior to its proximately higher genus in grade of determinate perfection, and, on the other hand,
inferior to its species (i.e., its other dividing member) in degree of determinacy,
though not in grade of perfection possessed. The genus animal is similarly
inferior to man, on the one hand, and to brute, on the other.
as in Diagram 1, all the "properly" specific concepts have the
•• In Diagram
same extension and comprehension because, as infima species, they are equally
determinate.

SOLUTION

OF THE

OF SPECIES

325

the disposition of concepts (or natures) as in the vertical axis of
Diagram 1, whether these concepts (or natures) be species or
genera; (2) by an "imperfect hierarchy" I shall mean the disposition of concepts (or natures) as in the vertical axis of Diagram
2, whether these concepts (or natures) be species or genera; (3) by
an " extensive hierarchy " I shall mean the disposition of concepts
(or natures) as in the horizontal axis of Diagram 2, in which the
ordering, from left to right, is according to the level of generality,
determined as to extension or comprehension. 59 The extensive
hierarchy is the familiar one set forth in elementary logic books:
it represents the steps of progressive division by which one passes
from a summum genus, in any category, to the infima species. This
extensive hierarchy must never be confused with either the perfect
or the imperfect hierarchy which represents steps of progressive
ascent or descent in a series of terms arranged according to perfection of being (whether the terms be natures, specific or generic, or
the concepts by which these natures are conceived) .60
11. We are now prepared to summarize the issue beween the first
and second theory, reformulated in the light of the rectification of
the first theory.
In the first place, it should now be apparent why the truth is not
a simple synthesis (in the Hegelian manner) of the first and second
theories, taking the truth from each, and excluding their falsehoods.
Yet I can see why some might think this to be the case: for the
second theory was certainly right in its insistence upon a genus
commonly predicable of diverse species; and if the first theory is
right in its insistence upon only one essential perfection (between
two proximately related species) as the root of the positive and the
negative differences which diversely determine the species, why, it
may be asked, cannot these two points be combined into a single
true theory? Why, in short, is not the first theory, as rectified of
its error about the common genus, the true synthesis? The answer
•• I have chosen the word "extensive" to name this third kind of hierarchy,
not because the criterion of extension is more fundamental than the criterion of
comprehension, in determining the various levels of generality, but because, as I
shall later show, this hierarchy is developed by acts of extensive (total) abstraction, in contrast to intensive (formal) abstraction.
60 The Tree
of Porphyry is guilty of having made precisely this confusion.
Anyone who studies Diagrams 1 and 2 will see that the Tree of Porphyry tries to
combine them without recognizing the radical difference between the way terms
are disposed in the vertical and in the horizontal axis. I shall return to this
point later, in Part VI, when I offer an historical hypothesis as to the origin
and persistence of false or confused theories about species, genera, differences-and their hierarchies.

MORTIMER ;r. ADLER

is as follows: although the first theory rectified now agrees with the
second in affirming a common genus, its theory of the common
genus diverges radically from the second theory's account of the
common genus. The divergence is on these four essential points.
(1) According to the first theory, the common genus is, through privation to one perfection, indeterminate in two respects, for it is
determinable by the possession and the rejection of that one
perfection; whereas, according to the second theory, the common
genus is, through privation to· two or more perfections, indeterminate in two or more respects, for it is determinable by the possession of each of these perfections. (2) According to the first
theory, the differences which constitute proximately related species
are always related as positive and negative determinations
(the
possession and rejection of one and the same perfection) ; whereas
according to the second theory, the differences which constitute
proximately related species are always related as positive determinations, each with respect to a diverse perfection. (8) According to
the :first theory, if two species are proximately related in a common
genus, the superior must have all the perfections possessed by the
inferior, and in addition one perfection the rejection of which constitutes the inferior species as determinate; whereas, according to
the second theory, if two, or more, species are proximately related
in a common genus, each one may have a perfection lacked by the
others, and in turn reject the perfections possessed by these others;
thus, considering two species in a common genus, each positively
determined by a distinct perfection, let us say j and k, it follows
that the possession by the one species of perfection j involves the
rejection of k, and conversely in the case of the other species. This
point, which is crucially important, can be summarized by saying
that in the second theory, the differences are related as contraries
because the diverse perfections, in which they are rooted, are so
related; whereas in the :first theory, the differences are contrary
only as positive and negative determinations rooted in the same
perfection, and there is no contrariety among diverse perfections.
(4) According to the first theory, each genus can be subject to only
a twofold division, by reason of its differentiation by a positive and
a negative difference; whereas according to the second theory, a
genus can be subject to a manifold division, by reason of its differentiation entirely by positive differences. 60 "
60 " With respect
to (4) above, it should be noted that, in Diagram I, each
genus (except animal) is divided by two terms unequal in their degree of determinacy, for one is always another· genus, and the other is always a species;

SOLUTION OF THE PROBLEM OF SPECIES

327

Hence we see that no resolution can be reached by trying to
combine the first and the second theories. Then what is the situation? Here are the possibilities.
(I) Either exponents of the second theory agree entirely with the
first-with respect to every point in its doctrine of species, genus,
difference, and hierarchy-or they still disagree with the first theory
as now rectified. If they do agree, then, for the most part, our
problem is solved. It would but remain to show that only a very
small number of species-probably not more than four-is compatible with the doctrine as agreed upon. Let us, however, take the
other horn of the dilemma, that of disagreement, and see what the
points of disagreement might be.
(2) Exponents of the second theory may still disagree about the
principle of perfect hierarchy. This would be the maximum disagreement, for such disagreement would include disagreement about
the character of the common genus, about the mode of differentiation of that genus, and about the number of species.61

(3) Exponents of the second theory may agree with the principle
of hierarchy, but insist that the right form of that principle is the
imperfect, not the perfect, form. Taking this position, they will
agree that there is a perfect hierarchy of such ultimate generic terms
as body, plant, brute; but insist that there is only an imperfect
hierarchy of infima species, because they are reached by the
progressive differentiation of the ultimate genera, through many
levels of sub-genera, and hence there are many generic interruptions
of the hierarchy of infima species; hence it is imperfect. Furthermore, if they take this position, the second theory must combine
two principles of hierarchy-the extensive hierarchy, in the horizontal axis, and the imperfect hierarchy, in the vertical, the former
not being a hierarchy of degrees of perfection in being, but only a
hierarchy of degrees of indetermination in being. Furthermore, if
whereas, in Diagram 2, each genus (except animal) is divided into two or more
terms equal in their degree of determinacy (i. e., having the same rank in the
extensive hierarchy). And the reason why animal is an exception both times is
precisely opposite for the two theories.
61 It is obvious that the second theory cannot deny perfect hierarchy without
denying the mode of difl'erentiation represented in Diagram 1, and if that mode
of differentiation is denied, the character of the common genus, as determinable
in a twofold way by a positive and a negative difference rooted in one and the
same perfection, is also denied. It will certainly follow, then, that the number
of species must be more than the five named in Diagram 2, but how many
more is not definitely indicated. That will depend, of course, upon how far the
second theory goes in its division of such genera as brute, plant, and body.

328

MORTIMER J. ADLER

they take thls position, the exponents of the second theory must
combine two different accounts of the nature of the common genus
and of the mode of differentiation, for it must employ the first
theory's account when it treats of the differentiation of animal into
brute and man (and so in all similar cases), but it must employ its
own divergent account when it treats of the differentiation of brute
into sub-genera, and these in turn into infima species (and so in all
similar cases). Finally, if exponents of the second theory take this
position, they must affirm a much larger number of species than can
be agreed to by the first theory.
(4) Exponents of the second theory may agree to the principle
of perfect hierarchy, and to all that that implies with regard to
species, genus, and difference, and still try to insist that there is a
larger number of species than four or five, or any such small, definite
number.
Of these four possibilities, let us eliminate the first at once, for
that would give us a resolution of the problem of species without
demonstrating the necessity of a solution in terms of the truth of
the first theory.
With respect to the three remaining possibilities (of disagreement), we can reduce the whole issue to a single point, framed by
the question, whether the order of species is a perfect hierarchy?
If the negative answer to this question can be demonstrated to be
impossible, then the affirmative answer is necessary, for the alternatives here have been shown to be exhaustive and exclusive. If the
second theory cannot hold to the negative answer (i. e., if it cannot
deny the principle of perfect hierarchy and all that flows from it
with respect to the nature of a genus and its mode of differentiation), then the second theory is absolutely untenable.
We can now narrow the issue even further, by making the proof
or disproof of the principle of perfect hierarchy turn on the question:
whether brute is a species (infima, of course) or a genus? If it can
be shown that brute must be a species, and cannot be a genus, then
it follows with obvious necessity that plant and body must also be
regarded as species, and not as genera: in which case, not only is
the second theory shown to be untenable in its denial of a perfect
hierarchy, but it is also shown to be wrong in its insistence on a
larger number of species than four, or perhaps, five.
If these things can be shown, the issue constituted by any disagreement between the second theory and the first theory, as rectified, will be resolved in favor of the latter. Yet one more step will
remain, for it will be necessary to show that the first theory, as
rectified, is not only justified in its opposition to the falsity of the

SOLUTION OF THE PROBLEM OF SPECIES

second theory, but that it is also free, in itself, from all internal difficulties: in short, that no objections to it remain unanswered. When
this is accomplished, as I think it can be, the problem of species
ceases to be a philosophical, and becomes an historical, problem.
The issue now being both clear and sharp, I turn at once to its
resolution.
IV.

THE ISSUE RESOLVED

U. Disproof of the second theory. The principle of perfect hierarchy is not· readily susceptible to direct proof; but it can easily
be proved by an indirect form of argument, by a reductio ad
impossible. 62 It may be that the principle of perfect hierarchy is
self-evidently true-immediately known by anyone who fully understands the notion of species itself. However that may be, the
principle does not appear to be self-evident to some, who speak of
species, genera, and differences, in a manner incompatible with the
principle. And even if the principle be self-evident, it is not improper to explicate its evident truth by having recourse to indirect
arguments, showing the impossibility of its denial.
Indirect argument always rests its case upon certain facts to
which the opponent must also agree. Because he agrees to these
facts, the argument will run, he cannot deny the ultimate proposition in question. Now, in this case, the facts upon which the argument for perfect hierarchy rests are the facts of human nature.
To make the grounds of the argument explicit, I shall state three
propositions about man, on which there must be agreement before
we begin. (1) Man is a rational animal. (2) Man has all the
essential perfections possessed by every other kind of corporeal
creature, and excels them all by possessing, in addition, an essential
•• That is why I said, at the end of the preced4Ig section, that I was going to
show the denial of a perfect hierarchy to be impossible, and thus indirectly to
show the necessity of the principle, rather than attempt a direct proof of the
principle. In The Problem of Species, the reply to Objection 1 against the first
theory includes two attempts to prove the principle of perfect hierarchy. The
first of these, a &:rect argument stated in two forms, fails, because it tries to
establish the principle in terms of the fact that a common genus is impossible.
Vd. op. cit, pp 168-176; THE THOMIST, IT, 108-117. The argument is not
entirely false: it does contain the truth that if by " common genus " is meant a
genus determinable by two or more positive differences, then there can be no
co=on generic natures if there is a perfect hierarchy of specific natures. But
it will be seen at once that the argument in this form begs the question, for it
argues from the principle of hierarchy to the denial of a certain type of common
genus. Whether there is a direct metaphysical proof of the principle of hierarchy,
in terms of the notions of common matter and substantial form, I am not sure.
For the present, suffice it to point out that the second, and indirect, proof of
hierarchy, given in The Problem of Species, was quite sound, and will be used
here. Vd. op. cit., pp. 176-180; THE THOMIST, IT, 117-21.

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MORTIMER J. ADLER

perfection which is man's alone. (8) Man is the end of all generation in the order of corporeal creatures. 623
These three propositions, I say, contain implicitly the truth of the
principle of perfect hierarchy. For by the first, we know that animal
is the proximate genus of man; and that, in the constitution of
human nature, the generic nature which is determined by rationality
is the (potentially rational) sensitive nature. By the second, we
know that every essential perfection, constitutive of any infrahuman nature (whatever or how many they may be), is actually
present in human nature, by reason of the virtual inclusion in man's
substantial form of every inferior substantial form. Hence, whatever order obtains among actually existing corporeal substances
according to their specific and generic distinctions, can also be found
in the structure of human nature itself. And, by the third proposition, we know that that order is finite: that it not only involves
a lowest specific nature, having the least degree of perfection, but
also a highest, having the greatest degree of perfection possible in
the world of corporeal things. 68
I shall not here repeat in full the indirect argument, based on
these three truths, which is carefully and explicitly presented in
The Problem of Species. 64 Instead I shall recast its main points,
by showing that the facts of human nature make undeniable the
first theory's account of the character of the common genus and its
mode of differentiation. Let us begin by supposing a state of affairs
contrary to the principle of perfect hierarchy, namely, that two
species differ within a common genus by two positive determinations
each rooted .in a distinct perfection. Now there are two possibilities
concerning the relation of these perfections: either they are contrary
••• The first of these propositions, being the definition of man, needs no textual
support for Thomists. The second of these propositions is one of the main lessons of QQ. 75 and 76 in the Treatise on Man (Summa Theologica, I). The
third of these propositions is the explicit teaching of Ch.
in the Summa Contra
Gentiles, III: ". . . Again, the vegetative soul is in potentiality to the sensitive,
and the sensitive to the intellective.
After this no later or more noble form
is to be found in things subject to generation and corruption. Therefore, the last
end of generation is the human soul, and to this does matter end as its ultimate
form. . . . Therefore, man is the end of all generation." Cf. ibid., IV, 97; and
Summa Theologica, I, 66, 2. Vd. Problems for Thomists, pp. 270-274; THE
THOMIST, II, 290-94.
•• The order is finite in one other sense: it is not only limited by an absolute
upper and lower extreme; but it must also have a finite number of steps between
the extremes, because essences are integral. There are no fractional degrees, no
intermediate forms, between natures which are specifically distinct, and which are
proximate by reason of the fact that their differences (positive and negative) are
rooted in one and the same essential perfection .
•• Vd. pp. 176-180; THE THOMIST, II, 116-20.

SOLUTION OF THE PROBLEM OF SPECIES

331

to one another, so that the possession of one necessitates the rejection
of the other, or they are cumulatively ordered, so that the possession
of one involves the possession of the other, but not conversely. If
the second alternative be the case, then the term which is constituted by posssession of the higher (the inclusive) perfection may be
a species, but the term which is constituted by possession of the
lower (the included) perfection cannot be a species, but must be a
genus. This is the way in which the terms man and animal are
related, or the term animal and living body (vd. Diagram 1); and,
in the latter case, both terms are genera, neither is a species. If,
however, the terms man and brute be compared, it will be seen
that brute is constituted not only generically by the possession of a
lower or included perfection (sensitive), but also specifically by
the rejection of a higher or including perfection (rational). Hence,
if two distinct perfections are cumulatively ordered, then both
cannot be roots of specific determinations, for, as we have just seen,
the higher of these perfections is the root of a positive, an,d specific,
difference in one of the terms being compared (e. g., man), and the
lower must be the root of a positive, but generic, determination in
the other term (e. g., brute): it cannot be the root of a specific
determination, (except in the proximately lower species, plant,
and then through a negative difference). Hence, if anyone compares
two terms as species, and wishes to regard the specific determination
of each as rooted in a distinct perfection, he must choose the other
"possible " alternative, namely, that these perfections are not
cumulatively ordered, but related as contraries, in such wise that
each of the species possesses one of these perfections and rejects the
other. But this other alternative is impossible, because then human
nature (even if man is not one of the two terms being compared as
species) would have to possess contrary perfections, by reason of
the fact that it virtually contains all inferior natures. The possession of contrary perfections violates the principle of contradiction. 65
Now, the principle of perfect hierarchy is identical with a third
alternative, namely, that two species differ within a common genus
by positive and negative determinations, both rooted in the same
perfection. Since the three alternatives considered are exhaustive,
the impossibility of the first two is equivalent to the necessity of
the third. And this constitutes the indirect proof (in the light of
•• This cannot be avoided by saying that matter can be in potentiality to contraries without violating the principle of contradiction. One cannot pass from that
to saying that human nature can virtually include contraries; for the simple reason
that virtuality is not the same as potentiality. If human nature virtually contained
natures constituted by contrary perfections, it would actually possess these contrary
perfections, which i8 imposBible.

MORTIMER J. ADLER

the facts about human nature) that the principle of perfect
hierarchy is true. 65 "
This proof accomplishes two things. (I) It shows that no one
can deny the principle of perfect hierarchy without also denying
that man, as a rational animal, possesses the essential perfections
of all other corporeal natures and is supreme in the corporeal order.
It shows that in so far as the second theory's account of genus
and difference diverges from the first theory's account of these
matters, the second theory of species is untenable, because incompatible with perfect hierarchy. Hence we can conclude that
Thomists (defined by their adherence to the three aforestated
truths about human nature) cannot hold the second theory of
species: they cannot deny a perfect hierarchy of species; they
cannot say that a common genus is determinable by two (or more)
positive specific differences, each rooted in a distinct perfection.
Only one more thing remains to be done. There still remains one
point of possible disagreement between the first and the second
theory which leaves an issue to be resolved, namely, the question
of the number of species. On no other point is disagreement between
the two theories possible for Thomists; but it may still be thought
that Thomists can disagree about the number of species. If now I
can show that even on this point disagreement is impossible for
Thomists, the issue is completely resolved, so far as it can be
regarded as a problem for Thomists. If I can show that the first
theory's account of the number of species must be accepted, I will
have shown that the second theory, in every respect in which it
might differ from the first, is absolutely untenable.
In proceeding with this last step of the demonstration, I now
••• The three alternatives are: (1) two. positive determinations, rooted in
distinct perfections cumulatively ordered; (2) two positive determinations, rooted
in distinct perfections related as contraries; (8) a positive and a negative determination, rooted in the same perfection. (That this is exhaustive will be seen by
anyone who tries to conceive further alternatives; others can be stated, but analysis
will show them to be completely inapplicable.) The third alternative belongs to
the first theory of the co=on genus and of its mode of differentiation; and this in
turn is the only theory of genus and difference compatible with the first theory of
species which affirms a perfect hierarchy. Hence, the principle of perfect hierarchy
is proved when this third alternative is necessitated by the impossibility of the other
two; and the above proof consists in showing their impossibility. The first alternative is impossible because positive determinations, rooted in distinct perfections
cumulatively ordered, cannot be determinations. of terms within a proximate
common genus; the second alternative is impossible because it violates the truth
that human nature virtually includes all inferior natures and actually possesses all
their essential perfections. The indirect proof given in The Problem of Species
(loc. cit., fn. 64, supra) is a fuller explication of this last point, and should be
consulted.

SOLUTION

OF THE PROBLEM OF SPECIES

888

have two sets of premises which Thomists must affirm: one is the
set of propositions about human nature; the other is the set of
propositions which explicate the principle of perfect hierarchy.
The proof to be given can be most effectively presented by focussing
it upon three crucial terms: animal, man, brute. If it can be shown
that brute must be a spec:ies, that brute cannot be a genus, it will
have been shown that the number of species cannot be more than
four, or at the most five; for if brute cannot be a genus, then
certainly, and on the strongest of a fortiori grounds, plant cannot be
a genus. The only question is whether body is a genus divided into
two species, element and mixture, or whether body is itself a species.
I say this is the only question, because even if body were a genus
thus divided, element and mixture could not in turn be genera, for
then there would be a larger number of species of inanimate than
of animate substances, which is impossible on the basic Thomistic
ground that higher forms are the principles of a great number of
distinct operations, than lower forms. 66 Whence it follows that if
brute is not a genus, there cannot be more than five terms in the
hierarchy of species, properly conceived. 67
Again the argument must proceed by a reduction to impossibility
of the " possibilities " raised in objection to the point at issue. There
are only two which can be offered. I take the weaker of the two first.
(I) Trying to argue that brute is a genus, the objector must
offer something by way of specific distinction among brutes. To
put his case in strongest terms, let us not suppose him to offer such
things as cow and ape as species, but rather mammal and nonmammal. This does not preclude him from saying that cow and
ape are species of mammal, if he is able to show that mammal and
non-mammal constitute an essential distinction (albeit a generic
,one) within the higher genus brute; but if he is unable to show that
mammal and non-mammal are essential divisions of brute, he is
certainly precluded from regarding any further divisions of mammal
as essential. Now, what are the differences by which mammal and
non-mammal might be constituted as species? They must be either
two positive differences rooted in distinct perfections : or they must
be a positive and a negative difference rooted in the same perfection.
Taking the first alternative, let us name the two positive differences
as the oviparous and the viviparous modes of reproduction. Each
86 Vd. St. Thomas Aquinas, In De Anima, II, Lect. 1, 280.
Cf. Summa Theologica, I, 77, 2. For a full explication of this point, vd. The Problem of Species,
pp. 58-61, 71-72; THE THOMIST, I, 244-47; 257-58.
81 I shall return later to the question of whether there are four or five.

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MORTIMER J. ADLER

is a positive determination of a generic power common to mammals
and non-mammals, because they are brutes, animals, and ultimately,
living things, having a vegetative nature. Each of these modes
of reproductive operation is a distinct perfection possible in the
sphere of animal life. But these distinct perfections are related as
contraries, not cumulatively. 68 The brute animal which possessses
the viviparous mode of reproduction rejects the oviparous mode,
just as much as, conversely, the brute animal which possesses the
oviparous mode rejects the viviparous. Hence, this manner of differentiating 'TJULm'TJULl and non-mam'TJULl violates the principle of
perfect hierarchy; wherefore we know that this distinction cannot
be an essential one, but must be accidental. We can conclude,
therefore, that so far as the objector proposes distinctions of this
sort, he cannot show brute to be a proper genus.69
Thus, the first type of "possibility " has been shown to be not at
all possible, and by this first type I mean any effort to differentiate
brute by positive differences, rooted in distinct and contrary per88 Strictly speaking, the use of the word " non-mammal,''
to name one of the
two kinds being distinguished, is incorrect, for the prefix " non- " should only be
used to name a genus, as compared with a species which possesses a cumulative perfection, with respect to which the genus is indeterminate, e. g., the sensitive nature
(the genus animal) is non-rational. Unfortunately, however, there is no word
to name the oviparous nature, in contradistinction to the viviparous nature, which
is mammalian. Nor does it make any difference to the essential point of the
argument if the facts of biological classification do not support the distinction of
mammals from non-mammals in terms of these two positive differences; for if
they do not support this distinction, the facts then strengthen the argument
against anyone who might try to argue that the distinction between mammal
and non-mammal is essential rather than accidental.
•• The force of this argument can be shown in a number of other ways. (1)
Because they siguify contrary perfections, viviparous and oviparous as the roots,
respectively, of two positive differences, cannot differentiate the brute genus into
species which are ordered as higher and lower in grade of perfection. (2) Because they are contrary perfections, rather than cumulative, human nature could
not include both, virtually or actually; hence either human nature does not include
all the es$ential perfections of inferior natures, or viviparous and oviparous do
not signify essential perfections, and hence cannot be the roots of proper specific
differentiation within the genus brute. (8) We know as a fact that man is a
mammal: the human mode of reproduction is viviparous. Now if viviparous signifies an essential perfection, and one less generic than that signified by sensitive,
the proximate genus of man is not animal (the sensitive nature), but mammal.
In which case, a truer definition of man would be to say that he is a rational
mammal, not a rational animal. But if it is absolutely true to say that man is a
rational animal, then viviparous must signify an accidental perfection (and thus
there would be nothing repugnant in the fact that human nature included some
of the accidental perfections to be found among the races of brute, and rejected
their contraries) . But if viviparous must signify an accidental perfection, then
mammal cannot be a species of brute, but only a race: which was to be proved.

SOLUTION OF THE PROBLEM OF SPECIES

885

fections. But those who wish still to insist that brute is a genus may
now have recourse to a second type of "possibility." As distinguished from "possibilities" of the first type, what is now offered is
the "possibility " that brute is differentiated by cumulative rather
than contrary perfections. On the face of it, such a " possibility "
would appear to be compatible with perfect hierarchy, for
tive perfections can be essential, as contrary ones cannot. Furthermore, in this case, the species of brute to be distinguished will be
differentiated by a positive and a negative difference, rooted in the
same perfection, not in two positive differences, rooted in distinct
perfections. Let us proceed to the argument.
(2) The objector might propose that brute, as a genus, can be
essentially differentiated into vertebrate and invertebrate. Here
vertebrate, like rational, signifies the positive difference, the possession of the perfection in question, whereas invertebrate, like irrational, signifies the negative difference, the rejection of that same
perfection; and just as animal is non-rational, and thus determinable by both rational and irrational, so brute, as a genus in turn, is
non-vertebrate and is thus determinable by both vertebrate and
invertebrate. Again it is not important whether the objector maintain that vertebrate brute and invertebrate brute are infima species,
or whether he merely hold that this is an essential, and generic,
division, each term of which is capable of further essential differentiation: for in either case, if we can show that the suggested division
of brute cannot itself be an essential one, it follows a fortiori that no
subordinate divisions can be. 70
To make the objector's case as strong as possible, I am going
to shift to another distinction which, for Thomists, is the best of
all the " possibilities " for an essential distinction within the genus
brute. I am going to substitute mobile and immobile for vertebrate
and invertebrate. All the formal properties, indicated above in the
discussion of vertebrate and invertebrate as positive and negative
differences rooted in one perfection, exist equally in the case of
mobile and immobile. And I say this in a stronger case, because the
distinction between mobile and immobile appears to be even more
generic (some mobile brutes being vertebrate, some being
brate); hence it should be easier to make a case for a more generic
essential distinction than for a less generic one. Furthermore, this
70 It should be noted that the second type of " possibility " forces the objector
to move to a higher level of the extensive hierarchy, set forth in Diagram 2; he has
been forced to move to the left end of the axis of that hierarchy. It is a significant fact that this second type of " possibility " can be offered only in terms
which are fairly proximate to brute, rather than in more remote terms.

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J. ADLER

distinction accords with the Thomistic divisions of sensitive life into
two modes, related as perfect and imperfect, according to the possession or rejection of mobility (the locomotive power) .11
The argument against the objection is as follows. The proximate
genus which is divided by mobile and immobile (as positive and
negative differences rooted in the same perfection) must either be
brute or it must be animal. Taking the first alternative, we must
say that the mobile brute nature is essentially more perfect than the
immobile. But if mobility is an essential perfection in the hierarchy
of species, then man must possess that perfection. We know in fact
that he does. And furthermore, we know that in the hierarchy of
cumulative perfections, rational is higher than mobile, for what is
rational is mobile, but not conversely. Now, in forming a definition,
the last positive difference is added to the positive differences which
are rooted in lower perfections, and as such positively determine
more generic natures. Hence, if all these things be so, we must
define man as a rational, mobile brute. But this is impossible, for
brute is itself defined as an irrational animal (thus constituted by a
negative difference within the genus animal) . We cannot say that
man is a rational, mobile, irrational animal, and therefore we cannot
regard mobile and immobile as essential differentiations of brute as
a proximate genus.
We are forced, therefore, to take the second alternative, namely,
that mobile and immobile essentially differentiate animal as a
proximate genus. But, then, since rational signifies a higher perfection than mobile, mobile animal would be constituted as a genus,
in turn differentiated, with respect to that higher perfection, by
rational and irrational as positive and negative differences. Disastrous consequences result from this. The definition of man becomes rational, mobile, animal, not just rational animal. But then
it is not the animal nature as such which is indeterminate with
respect to rationality as a perfection, but only the mobile animal
nature, for only that to which the last positive difference is proximately added is the genus indeterminate with respect to the perfection
in which the last difference is rooted. And this same genus, because
of this indeterminacy, is doubly determinable-not only by the
positive difference but also by the negative difference which is
rooted in the same perfection. Whence it follows that mobile animal
71 Vd. Summa Theologica, I, 78, L
Cf. Summa Contra Gentiles, II, 95, where
it is said that " one species has an additional grade of perfection over another,
for instance, animals endowed with locomotion over those that ·are immovable."
I might add that if mobile and immobile are species dividing brute, then that
genus must be conceived as non-mobile.

SOLUTION OF THE PROBLEM OF SPECIES

887

as a genus is proximately divided into rational and irrational mobile
animal; and it becomes impossible to explain the fact that some
irrational animals are immobile. All of this can be summarized in
two facts: (I) the mobile is divisible into the rational and the
irrational.
The irrational is divisible into the mobile and the
immobile.
Thus it is shown that mobile and immobile cannot be differentiae
constituting an essential distinction. For either mobile is higher
than rational in the ascending order of essential perfections, or
rational is higher than mobile; but neither alternative is possible
because, in the first, man must be defined as a mobile, rational
animal, and brute as a mobile, irrational animal, which is impossible
if there are, in fact, immobile, irrational animals; and, in the second,
man must be defined as a rational, m.obile animal, and brute as an
irrational, mobile animal, which is impossible if there are, in fact,
irrational, immobile animals. Or, to say the same thing one other
way, there are only these two " possibilities ": that animal or that
brute is the proximate genus essentially divided by mobile and immobile. But we have seen that neither is possible; wherefore we
must conclude that mobile and immobile cannot constitute an
essential distinction. Mobile must, therefore, like oviparous and
viviparous, signify an accidental perfection, even though, unlike
them, it appears to have no contrary opposite, but only a
negative. 72
72 The full force of this proof is contained, in The Problem of Species, in Objections 6 and 7 against the second theory as there expounded: Objection 6 showed
that brute cannot be a genus if man is defined as a rational animal; Objection 7
showed that any differentiation by positive and contrary determinations cannot
constitute an essential distinction, such determinations being rooted in accidental
perfections. Vd. op. cit., pp. 157-168; THE THOMIST, n, 99-104. These objections
could not be answered except in an evasive manner. The arguments I· have now
stated are better by reason of the fact that no evasion remains possible any
longer.
It is also worth pointing out that the foregoing argument has uncovered the sign
which tells whether distinctions are accidental or essential. The fact that when
brute is divided by mobile and immobile and also by vertebrate and invertebrate,
these two distinctions cannot be ordered in a single way-this fact shows that
the distinctions are accidental. (For if brute is first distinguished into mobile and
immobile, each of these in turn can be divided into verterbrate and invertebrate;
and if, on the contrary, the first division is into vertebrate and invertebrate, then
each of these in turn can be distinguished into mobile and immobile. When
terms are related in this way we know definitely that they cannot be involved in
essential determinations of any genus. For essential determinations are always
well ordered with respect to one another, accidental determinations are not. This
is apparent in the argument: the fact that mobile could not be well-ordered with
respect to rational showed that either or both were accidental perfections; but

11

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MORTIMER J . .ADLER

The conclusion just reached completes the argument against
the second theory. Since no possible way can remain, in which it
can be argued that brute is a genus (all the "possibilities"
having been shown to be strictly impossible), the conclusion that
brute is a species becomes inescapable. And, as I have already
shown, if brute is a species, then the number of specific natures
(in a perfect hierarchy with man supreme) is either four or
five. With the exception of the dubious point about number
(four or five), the order of natures, specific and generic, is that
pictured in Diagram 1. 73
Nor can this conclusion be avoided by one who says that the
whole argument rests on the particular examples employed; and
who goes on to say that, although the terms chosen do not signify
essential determinations, perhaps, there are other terms-terms
we do not now know, which could accomplish what is being sought,
namely, the further specification of brute as a genus. The answer
is simply that there can be no perhaps about it, if we do now know
that man is a rational animal. Of course, if Thomists are willing
to admit that they do not now know the nature of man (the definition and structure of that nature, and its place among all corporeal
things), then they can also say that there may be essential determinations of brute, which we do not now know. But unless
ignorance is frankly asserted in the one case, it certainly cannot
even be supposed in the other. 73 "
since we know that rational signifies an essential perfection, we must conclude
that mobile signifies an accidental one.)
73 On the question of number, the argument given in The Problem of Species,
was sound, but not sufficiently determinate.
Vd. the reply to Objection
against the first theory (pp. 181-188; THE THOMIST, II, 122-!'l9), in which it was
argued that there could not be more than ten species in a perfect hierarchy, because
of the order of essential perfections possessed by man, as these are signified by
the specifically distinct human powers, in their various conjunctions and separations. At that time, I favored the position that there could not be as many as
ten (though ten seemed possible), because of St. Thomas's position on the number of souls, and especially his insistence on the point that the locomotive power
does not signify a distinction in grades of soul, but only in modes of animal
life, as perfect and imperfect. Vd. Summa Theologica, I, 78, I; cf. Problems j01'
ThomY1ts, pp. 187 fi.; THE THoMIST, II, 128 fi. · We now see that the Thomistic
position with respect to three as the number of souls is thoroughly justified by
the proof that brute is not a genus, and that there cannot be more than three
species of living things. The use of the word " species " in the passage quoted
from Summa Contra Gentiles, II, 95 (vd. fn. 71 supra), must, therefore, be treated
as an ambiguity. I shall later discuss such ambiguity in the use of words like
" species " and "
78 " The point here being made is extremely important.
It has traditionally been
supposed that there are essential perfections which we do not know, and hence that

SOLUTION OF THE PROBLEM OF SPECIES

889

Yet it is true that the arguments presented seemed to rest upon
particular examples. In order to remove the last trace of doubt
about them, I shall now formulate the reasoning with complete
abstractness. Whenever a genus is essentialiy divided by a positive
and negative difference rooted. in the same essential perfection (as
required by the principle of perfect hierarchy) its proximate
members must either be two species or a genus and a species.
Whenever the proximate dividing members are a genus and a
species, the member determined by the positive difference must be
the genus, and that determined by the negative difference must be
the species. If this were not the case, the genus could not in turn
be divided by differences rooted in a higher essential perfection.
There is only one case in which the proximate dividing members
of a genus are both species. That is the case of animal, the proximate genus of man and brute. In this case, as in every other, the
member determined by the negative difference (irrational) must be
a species. This case diverges from every other only in the fact that
the member determined by the positive difference (rational) is also
a species, rather than a genus. This we know to be true from our
knowledge of the facts of human nature, and from our knowledge
of those facts, we also know that every essential human perfection,
hierarchically inferior to that signified by rational, enters the conception and definition of man as a species, by way of the generic
constituents, ordered as proximate or remote in various degrees
according to the grade of the perfection by which they are positively
determined. All of this is necessitated by the very principles which
define a perfect hierarchy, as that is constructed in Diagram 1.
Hence, on purely formal grounds it is proved that brute must be a
we are justified in employing accidental perfections in the differentiation of species,
i. e., by using properties or even contingent accidents as signs of substantial
differences even when we do not know what these substantial differences might be.
But this supposition is absolutely invalid on the ground that human nature virtually
includes all inferior natures and actually possesses the essential perfections of all
infemor things, eminenter. Since we claim to know the structure of human nature
adequately, we cannot consistently say that there are inferior species whose substantial differences are rooted in essential perfections not known to us. Hence we
are entitled to employ proper or contingent accidents as signs of substantial
differences only with regard to those which are rooted in known essential perfections--known through our knowledge of man. In fact there are no others. This
point explains why the second theory of species cannot be defended on epistemological grounds (in terms of our supposed ignorance of essential perfections by
which ma.'ly species of brute, let us say, are differentiated).
The epistemological
excuses given by defenders of the second theory are untenable in the .light of the
three truths about human nature. The issue in the philosophy of nature cannot
be thus evaded. Vd. The Problem of Species, Ch. Ill; THE TnoMJsT, I, 11!!-20.
Cf. fn. 87, infra.

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J. ADLER

species, and cannot be a genus. And the whole proof rests, first,
on the truth of the principle of perfect hierarchy, and, ultimately,
on the fact that that truth cannot be denied without denying the
facts of human nature. 74
13. Proof of the first theory. The disproof of the second theory
does, in a way, constitute a sufficient proof of the first theory, for
it has now been shown that no point, in which anyone might disagree with the first theory, is tenable. No tenable second theory
remains, therefore. But there may still be difficulties intrinsic to
the first theory, difficulties which remain even after any alternative
theory is completely discountenanced. If this be the case, then the
issue has been resolved, but the problem of species has not been
fully solved. If this be the case, furthermore, we cannot say that
our answers to questions about the order and number of species
(or specific natures) have the demonstrative certitude which is the
ideal of philosophical work. Hence, in order to show that the
problem is solved and that our answers are certain, we must
complete the demonstration by showing that no essential difficulties remain in the first theory, considered by itself. I shall
proceed to do this by considering all of the objections to the first
theory with which I am acquainted. I cannot, of course, say that
these are the only ones possible. I can only say that these are all
I know. To that extent, any proof must fall short of absolute
certitude. I shall take up the several objections in the order in
which they have become known to me.
(I) In writing The Problem of Species I myself framed two
objections against the first theory-objections which did not arise
from the opposite second theory, but from difficulties I perceived
in the first theory, according to its own principles. These were
objections 6 and 7.75 The sixth objection said that it seemed to be
impossible to formulate the essential distinction between element
and mixture as the species proximately dividing the genus (nonliving) body. The seventh objection said that if each specific nature
were as such the generic constituent in the nature of its proximate
superior, then the lowest nature in the hierarchy could not be
conceived as having a genus at all. This objection would hold,
74 This argument
can be summarized in a single hypothetical syllogism: If man
is the highest species, and if animal is man's proximate genus, then brute, the
other member dividing that genus, cannot be a genus, and must be a species.
The syllogism is resolved by the categorical affirmations that man is the highest
species, and that man's proximate genus is animal .
•• Vd. op. cit., pp. !'l02-iW6; THE THOMIST, II, 143-47.

SOLUTION OF THE PROBLEM OF SPECIES

341

however that lowest nature were conceived-as element or simply
as body. At the time, I found it impossible to answer either of
these objections satisfactorily. Therefore, in concluding the book,
I wrote that neither the first theory nor the second theory had been
proved, because each had unanswered objections against them.
The issue was not resolved, nor the problem solved, and it would
not be until one or the other theory freed itself from such objections.
If they were unanswerable, we had a perennial problem on our
hands-and a problem (not a mystery) is the one thing which
should not be perennial in philosophia perennis.
I now know that these two objections can be answered satisfactorily. I take the seventh objection first, because the other one is not
really a serious difficulty. The difficulty in the first theory, pointed
out by the seventh objection, beset it entirely because of my own
error in formulating that theory. That error-the denial of a common genus-has now been rectified. With a true account of the
common genus, and of its differentiation by positive and negative
determinations, the first theory no longer has any difficulty with
regard to the genus of the lowest species; for if that species be
conceived as body, its genus is the corporeal nature conceived as
indeterminate in two ways with respect to one perfection, i. e.,
the perfection signified by vegetative life: as determined positively
(the possession of that perfection) a superior nature is conceived
(i. e., the proximately higher genus, living body); as determined
negatively (the rejection of that perfection), the lowest nature in
the hierarchy is conceived (i. e., that which is signified simply by
body). All of this is shown in Diagram 1. The solution of this
difficulty would be the same if the lowest nature were conceived as
element, rather than as body.
So far as the other objection (the sixth) is concerned, I would
now answer it by saying that our lack of knowledge of any essential
distinction between element and mixture-i. e., any distinction
which would be compatible with the principle of perfect hierarchyis sufficient evidence of the fact that no such distinction exists;
and that the species body is accidentally divided by whatever
element and mixture signify, just as the species brute is accidentaliy
divided by what mobile and immobile, or vertebrate and invertebrate, signify. The various elements and mixtures are simply racial
(i. e., accidental) types of body; and this remains the case however
they are ordered inter se, for a set of accidental types may be
ordered hierarchically among themselves. Hence the fact of the

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MORTIMER J. ADLER

apparently hierarchical disposition of the so-called elements, according to the atomic table, does not affect this argument. 76 I
realize that this answer to the objection is relatively weak; but the
objection itself is weak, for it makes no fundamental difference to
the principle of perfect hierarchy whether there be four or five
species. Though I shall henceforth speak of four, rather than five,
species, I will remain aware of the uncertainty about this one
point-uncertainty
arising from the manifest contingency that
progress in the experimental physical sciences, accompanied by a
deeper understanding of their findings in terms· of hylomorphic
principles, will some day teach us the essential distinction between
element and mixture within the genus body. 71
(2) I turn next to the objections which I have derived from criticisms of The Problem of Species a:: published. So far as the critical
discussion was at all pertinent, it raised only one objection to the
first theory as expounded in the book, namely, that the first theory
could not be true if the denial of a common genus was a point
essential to it.78 The objection was entirely sound; and it would
have been totally unanswerable, and totally destructive therefore,
if the denial of a common genus had not been an error on my partan error which I have now completely rectified, showing that the
denial of a common genus was no essential part of the first theory. 711
78 Even if the atomic elements, considered inter se, formed a perfect hierarchy,
they would all be species in the same genus, and thus the total hierarchy of species, considering species of mixture and species of plant as generically higher,
would be imperfect, because that total hierarchy would be subject to many
generic interruptions .
.. Cf. Problems for Thomists, pp. 232-238; THE THOMIST, n, 252-58. What is said
in the text above applies equally to the traditional position which regards element
and mixture as genera, for if they cannot be essentially differentiated as genera,
neither can they be as species.
•• In one form or another, this was the difficulty brought to my attention by
Prof. Pegis and Father Smith. Vd. fn. 6 and 9 supra. I see now that this difficulty was also being pointed out by M. Maritain in his Preface; but I did not
see it at the time I replied to his Preface, as that reply itself all too plainly
reveals:
•• May I say, in some extenuation of my error, that I was entirely right in
regarding as quite essential to the first theory the denial of what I took to be
the second theory's doctrine concerning the character of that common genus and its
mode of differentiation. For a common genus which is determinable by two or
more positive differences, rooted in distinct and contrary perfections, is absolutely
incompatible with a perfect hierarchy; as I pointed out in the book many times,
such determinations must be accidental, not essential, and so also the perfections
in which they are rooted. Unfortunately, the book as written is everywhere filled
with unqualified denials of a common genus, just because it is everywhere filled
with affirmations of a perfect hierarchy. If anyone now reads the book, in the

SOLUTION OF THE PROBLEM OF SPECIES

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(3) I turn finally to objections which have occurred since I discovered my error and thereby corrected my formulation of the first
theory. 80 There are three of these, all of which seem: to me to be
answerable.
(a) The first difficulty is that all of our ordinary empiriological
visualizations run counter to the supposition that there are only
four species. All the available evidence points to real discontinuities among subordinate kinds of brute or plant or body. These
discontinuities, it is claimed, are our intuitive warrant for seeing
many more really distinct species in the corporeal order than the
four named. The answer is twofold. In the first place, mere discontinuity by itself is not a sufficient criterion for specification.
While it is true that proper species are necessarily discontinuous,
because essences are integral, with no fractional degrees between
them, the converse is not necessarily true at all, that is, it is not
necessarily true, wherever we find discontinuities among kinds, that
those kinds must be proper species, essentially distinguished. Thus,
it is quite possible that the so-called elements enumerated in the
atomic table be accidental types of body, even though they appear to
form a well-ordered series of integral (discontinuous) kinds. As the
classification of racial types according to accidental distinctions does
light of this article, he must trouble himself to interpret the words " common
genus " as sigoifying the sort of common genus which must be denied by any
true analysis of species. He must also trouble himself to interpret my oftrepeated opposition between an " ontological " hierarchy and a " logical " hierarchy as sigoifying the radical difference between a perfect hierarchy (Diagram
1), on the one hand, and an extensive hierarchy (Diagram 2), on the other.
When I spoke of a " logical " genus I meant the sort of accidental genus in an
extensive hierarchy. I shall return to this last point again. Of. fn. 93, infra.
80 I promised the reader that I would say how M. Maritain
reacted to t'he corrected first theory, and to the demonstrative implications which followed from the
correction. I was able to present the substance of this article to M. Maritain
at the end of our conversations in Chicago, though not in as finished or as
explicitly stated form as here presented. At that time, Mr. Maritain raised only
three further difficulties, which I shall now try to answer. It should be noted
that these difficulties all concern the number of species, and not the principle of
perfect hierarchy. To the latter, Mr. Maritain agreed, though neither of us saw
at the time all of the implications of the principle. In venturing to report M.
Maritain's only remaining difficulties with the first theory, I must ask the reader
to be considerate of two facts: (1) M. Maritain has not read this article, and
in so far as it is a more precise statement than I could make in conversation, his
ultimate judgments may be altered by it; (2) M. Maritain, with or without reading this article, may after much more mature deliberation have come to judgments and may have discovered difficulties with which I am not acquainted.
What is here written must, therefore, be read as of this time of writing. I sincerely hope that M. Maritain will himself publish an ample discussion of all
the matters herein treated.

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MORTIMER J. ADLER

not find an imperfect hierarchical ordering of these types repugnant,
so neither does it find a discontinuous ordering of them repugnant.
And, in the second place, it is a very real question, raised in the
light of the best scientific evidence, whether, in the sphere of living
things, for example, the apparent discontinuities are not themselves
entirely of accidental origin-i. e., due to the extinction of intermediate varieties, or to the operation of purely accidental causes
preventing the generation of such intermediate types. In other
words, the order of brute racial types or plant racial types may be
like a spectrum, on the surface of which certain accidental interference effects have occurred, thus preventing us from seeing the
underlying continuity, and causing us to suppose an essential discontinuity among the accidentally separated colors. This, it seems
to me, suffices as an answer. 81
(b) The second difficulty-is that man does appear to have some
of the perfections found among brute creatures: man is mobile,
a vertebrate, a mammal, omnivorous, etc. Now if, according to the
first theory, these perfections are involved in the accidental, not
essential, determination, of either the animal, or of the brute, nature,
some explanation must be given of the fact that human nature
shares in the possession of these perfections. Before I try to give
the explanation asked for, let me point out the significance of one
aspect of the fact which generates the difficulty: that man has only
some of these perfections, found among brute creatures, shows that
these perfections must be accidental; for man has all the essential
perfections to be found among inferior creatures; and that man
could not have all the perfections of the sort named follows from
the fact that accidental perfections are contrary to one another,
and not cumulatively ordered. 82
The explanation is as follows. The specific brute nature is
determinate essentially, but not accidentally: it exists in many
diverse racial forms, and these forms can be ordered (imperfectly)
from lower to higher according as they accidentally realize the
81 For a similar answer to a similar objection, see Reply to Objection 5 against
the first theory in The PToblems of Species, pp 198-202; THE THoMisT, II, 193-43.
For a fuller explication of the point being made in answer, vd. ibid., pp. 246-271;
TRE THOMIST, II, 266-91; and especially consult the work therein cited as affording
the best survey of all the evidences which can be drawn from the field of
of Species, New York,
genetics: i.e., T. Dobzhansky, Genetics and the
1987.
•• I suggest that mobile and immobile, vertebrate and invflrtebrate., only appear
to be ordered in the way that raticmal and irrational, sensitive and insensitive, are.
If what is signified by these accidental perfections is closely scrutinized, it will be
found that mobile and immobile are contrary in the same way that ovipaTous and
viviparous are.

SOLUTION OF THE PROBLEM OF SPECIES

845

sensitive nature more and more fully: so that among irrational
animals, some are better able than others to achieve the telos of the
sensitive life.88 But man is a rational animal, and as such he is
sensitive eminenter. It is both natural and fitting, therefore, for man,
sharing the same generic sensitive nature with brutes, to possess
those accidental perfections which are most favorable. to sensitive
life, rather than their less favorable contraries. If man had evolved
from the higher races of brute by processes of purely natural generation, the point under consideration could be causally explained.
How much more so, then, is that the case in the light of man's
creation as a species, since every extrinsic sign of the divine plan of
creation points to a perfect hierarchical ordering of all things, both
essential and accidental. 84
(c) The third difficUlty is supposed to arise from the fact that
matter is unintelligible in itself and a source of unintelligibility in
whatever it helps to constitute. In the light of this fact, it is said
that if brute, plant and body signified species, "the world of matter
would not be as hidden from us as the true character of matter
demands." 85 We should not be able to know, by essential definitions, any specific nature inferior to man. Man alone is excepted,
because the rational nature exceeds the potentialities of matter by
its intellectual powers. Now I may not understand this objection,
but as I do understand it, it seems to me either to prove too much
or to have no force at all.
8 " Since further accidental determinations of a species m1,1st be on the part of
the perfections of the nature signified, they must be with respect to the generic
characteristics of each species inferior to man, since in each of these cases, the
specific difference does not signify a perfection possessed, but one rejected. Hence,
it is incorrect to regard such accidental perfections as mobile, vertebrate, viviparous, as belonging to the specifically brute nature; rather they belong to the
generic sensitive, or animal, nature, and that is why man can share in their possession, for he shares the same genus with brute.
•• We find the hierarchy of corporeal natures exhibited within the structure of
human nature, not only with respect to essential perfections, but also with respect
to accidental perfections. I suggest that we call those brute races higher, which
most closely resemble man in the accidental perfections determining the generic
sensitive nature. I suggest, furthermore, that we are able to -discern more of a
hierarchical ordering among brute races than among plant races, precisely because
the accidental similitudes between man and brute are greater than between man
and plant (the vegetative nature being a remote genus, the sensitive nature proximate) . It is interesting to observe, in this connection, that metaphorical comparisons between man and brute races (the lion-like, the fox-like, the pig-like
man) are much more frequent and pointed than those between man and the
plant races.
•• The Problem of Species, Preface, p. x. M. Maritain raised this point in his
Preface, but he also thought it was worth repeating as a final objection to the
truth of the first theory

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MORTIMER J. ADLER

For, on the one hand, it is admitted that we can define, by real
definitions, the several generic natures which are inferior to and
included in human nature. But these generic natures are entirely
immersed in matter; they do not exceed its potentialities in any
way. Not only can we define these genera, but it is admitted that
we can know precisely how many there are. 86 Furthermore, the
genus should be less knowable than the difference, for the genus is
taken from the matter, and the difference from the form.
And, on the other hand, I say that the objection has no force
because matter is a source of unintelligibility only in accidentally
constituted natures, and not in essences. The individual nature is
unintelligible to us because matter is a determinant of individuality;
and, similarly, the various sub-specific racial natures are unintelligible (i. e., not definable by real definitions) because, like the
individual nature, they are accidental, not essential, unities. Hence,
on the supposition that brute, for example, is a genus and that there
are many species of brute, I can understand why it might be said
that the reason we cannot define these supposed species is that the
unintelligibility of matter prevents us. The explanation is appropriate for the facts, but it may be equally appropriate on the contrary supposition, namely, that brute is a species; for then it would
be equally true to say that we cannot define the brute races because
they are accidental classes, and again the unintelligibility of matter
is a cause. In short, the unintelligibility of matter is not a premise
which can help us to determine what are and what are not specific
natures; rather it is an explanation of the inadequacy in human
knowledge of the corporeal world. If we could know, in fact, that
there were more species than we could define, we could refer this
inadequacy in our knowledge to the unintelligibility of matter; but
if, as a matter of fact, there are no more species than we can define,
then our knowledge is inadequate only with respect to racial and
individual natures, and this inadequacy can also be explained by
reference to the unintelligibility of matter. The unintelligibility of
matter does not, a priori, indicate the precise limitations of human
knowledge; it is only after we have discovered these limitations by
making our best efforts to know, that we can refer, a posteriori, to
•• M. Maritain admits that we can form real definitions of what he regards as
generic natures, such as brute, plant, body. But the fact that we can form such
real definitions does not, of itself, tell us whether these natures are properly
generic or properly specific. Hence, if it has been shown that these natures are
properly specific, it cannot be an argument, against such demonstration, that we
have real definitions of these natures.

SOLUTION OF THE PROBLEM OF SPECIES

847

the unintelligibility of matter as an explanation of whatever limitations we have found; 87
This objection may be presented in a second form. It may be
said that the reason why we know the essence of man, and of no
inferior species, is that man is sui generis-" that man is a world
in himself, a world contradistinguished from the whole world of
other animals, and even from the whole world of other corporeal
substances." 88 I do not think this point can be sustained, for though
man is on the boundary line between the corporeal and spiritual
worlds, he is strictly in one order of creation, not the other. H man
were truly and literally a world in himself, essentially contradistinguished from the whole corporeal world, it would be false to
say, as St. Thomas does, that man is the end of generation in the
corporeal order; it would even be false to regard animal as an
univocal genus common to man and brute, for the word " animal "
would then become strictly equivocal. I do not deny that man has
a special character: he is not only specifically distinct from the
proximately inferior species brute, but he differs from the whole
corporeal creation in two other essential respects: he has a power
87 I wish to stress one point involved in my. answer to this objection.
It is
that we cannot know that there are, in fact., more species than we can know
(i. e., know quidditatively, define by real definitions). I think I have demonstrated this point completely in my discussion of the several epistemological
hypotheses concerning our knowledge of specific natures. I think I have shown
that we cannot infer anything from our ignorance, and that the epistemological
question (how many species can we define?) cannot be answered until the ontological question (how many species are there?) is first answered. Vd. The Problem of Specill8, Ch. Til, esp. pp. 40-47; TBE TBOMIST, I, 112-fW. If this be true,
then M. Maritain's employment of matter's unintelligibility is based upon a
supposition which he cannot make; and, furthermore, he cannot use matter's unintelligibility to support this supposition in the absence of independent and demonstrative evidence that there are many species which we cannot define. Such evidence
would be a positive proof of the truth of the second theory, as against the first,
and we have seen that it simply does not exist; more than that, it never will be
found, if the principle of perfect hierarchy is true. Of. fn. 73a supra.
Nor can it be said that we lack real definitions of species because the substantial form, which is the principle of the difference, cannot be directly known.
That is true, of course, but it is equally true of the human and of inferior species.
We never abstract a substantial form from matter, as we abstract accidental
forms from the subjects in which they inhere. All of our knowledge of substantial
forms (the soul, for example) or of substantial essences is a posteriori, i. e., by
steps of
from accidents, to properties to essence, as in the case of the
human soul we know its essence by inference from its operations to its powers,
and thence to its essence. (It is a paradoxical fact that substantial forms are
not directly knowable by us precisely because they are intelligible forms; whereas
because they are sensible, and lie on the surface of a substance, accidental forms
are directly knowable by sense, and capable of immediate abstraction by intellect.)
88 The Problem af Specill8, Preface, p. xi.

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MORTIMER J. ADLER

which totally exceeds the potentialities of matter; and his substantial form is naturally incorruptible per se. But these differences
do not warrant us in saying that, as an object of definition, the
human essence is peculiar. They do not warrant us in concluding
that the only species we can define is man; and hence there can be
no objection here to the tenability of the first theory. 811
There is a third form which the objection can take, but in this
form it presents no difficulty whatsoever for the first theory. On
the contrary, what is now to be said is affirmed by the first theory
as an essential part of its own doctrine. If, it is said, there is a
hierarchy of species as grades of being, that hierarchy of unequal
essences must also be a hierarchy of grades of intelligibility: from
God down to the lowest species of substance, from the Creator who
is perfectly intelligible to the least intelligible of His creatures. But
the intelligibility of things can be regarded in two ways : either
secundum se or quoad nos. All the natures above man are more
intelligible in themselves, but less intelligible to him; but it is also
true that all the natures below man are, not only less intelligible
per se than human nature is, but also less intelligible to man than
his own nature. To point out that in the degree to which they are
inferior to man, the infra-human species must be less and less
intelligible to him, does not constitute an objection to the first
theory. It can be offered as one only on the supposition that this
fact is incompatible with a point claimed by the first theory, namely,
that we know all the corporeal species adequately, that is, by real
definitions. Since every real definition is, as a mode of knowledge,
formally the same, the equal adequacy with which, according to the
60 The fact that rational, which signifies man's difference, also signifies an immaterial perfection does, of course, have unique consequences. The races of man
are few, in comparison with the races of brute or plant; and furthermore, these
human races differ accidentally inrer se in the same way that brute races do,
namely, with respect to accidental determinations of the generic sensitive nature,
which man and brute share. There cannot be any further universal determinations
of man's specific difference, (i. e., his intellectual nature), though men do differ
substantially as individuals. That is precisely why there cannot be a higher
species than man in the corporeal hierarchy. The facts about man's uniqueness
are the very facts which make human nature absolutely supreme in the corporeal world, which make its hierarchy finite, which make man its final term of
geiteration. In short, these facts are perfectly harmonious with the truth of the
first theory; they need not be interpreted in the way exponents of the second
theory suppose: as explaining why there are no species of man, whereas there are
species of brute and plant as genera. Exponents of the second theory try to say
that man is a species, whereas brute is a genus, because man's difference is an
immaterial perfection. The truth is rather that the immateriality of the perfection
underlying man's specific difference· makes man the absolutely highest species in the
corporeal order. Cf. The PrOblem of Species, Preface, pp. x-xi.

SOLUTION OF THE PROBLEM OF SPECIES

349

first theory, we know all corporeal species is thought to be inconsistent with their gradation in intelligibility quoad nos.
It is necessary to show this supposition of inconsistency to be
false. While it is true that all real definitions are equal as knowledge, it does not follow that we know everything we can thus define,
with equal adequacy, in the full sense of that word. A real definition
is the source of adequate knowledge of the substance defined only
to the extent that we can see, through that definition, how the
properties flow from the essence. We have adequate knowledge, in
the full sense; only in the case of man; and we have it there because
human nature as an object of human knowledge is unique-it is the
only object of reflexive knowledge. We do not and cannot have such
knowledge of brutes or plants or bodies. But we can understand the
essence of brute more adequately than we can understand the essence
of plant, and of both of these much more adequately than we can
understand the essence of body, precisely because our reflexive
understanding of human nature illuminates the proximately generic
sensitive nature we share with the brute species more than it does
the remotely generic vegetative nature we share with both brute
and plant species. And that we understand the essence of body
least adequately of all follows from the fact that the purely
corporeal aspect of our human nature falls entirely outside the light
of reflexive knowledge. In short, though we possess real definitions
of all the species in the corporeal hierarchy, we understand the
essences of the members of this hierarchy in degrees of adequacy
which are directly proportionate to their proximity to man, whose
essence we understand with the maximum adequacy to which
human knowledge can attain. What is more proximate in nature to
ourselves, we understand better; more intimately, more fully,
because the intimacy and fullness of our self-knowledge casts a
reflected light upon what is essentially more like ourselves. Thus,
the truth that the hierarchy of corporeal essences, graded in being,
must also be a hierarchy of grades of intelligibility is not incompatible with the fact that we know each of these essences by a real
definition; for even the lowest essence is intelligible per se, and it,
therefore, has some intelligibility quoad nos, however inadequate
that may be: 90
9 ° C£. The Problem of Specie;s, pp. 281 ff.; THE THOMIST, n, 251 ff.
Professor
Charles DeKoninck illuminates the point under discussion by saying: " An intelligence constrained to time, and which contemplates the universe at its beginning,
or whose vision is limited to the natural inferior forms, would be able to see or
predict with certainty only the human form. . . . That spirit would predict
infallibly vegetative and animal life, but it would not know determinately all the
ways in which they could be realized" (op. cit., pp. 278-74; THE THOMIST, n,
298-94).

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MORTIMER J. ADLER

Thus are answered all the objections to the first theory with
which I have become acquainted. Until further difficulties, now
unknown to me, are raised, I feel justified in concluding that the
first theory is proved, and the problem solved. What seems to me
the most extraordinary confirmation of the first theory's truth is
that, from beginning to end, every one of its essential points flows
from the same insight-that we can reach a demonstrative knowledge of the order of nature through our reflexive knowledge of man.
However weak is our capacity for knowing because, being sensitive
creatures, we are rational rather than intellectual, and even though
we abstract ideas from sense, and reason discursively, we nevertheless share with the angels the reflexivity which is characteristic of
intellect. Here is a note in the proper analogy between human and
angelic knowing-the power which both human minds and separate
intelligences have for knowing the essence of all that is beneath
them, through knowing themselves. 91
V. CONSEQUENCES

OF THIS RESOLUTION

14. The fourth part of The Problem of Species considered the
consequences of a tentative resolution in favor of the first theory.
The fact that the resolution need no longer be regarded as tentative-that the first theory can be regarded as true rather than as
merely more tenable-in no way alters the implications which can
be drawn, so far as these concern, in general, the relation between
philosophy and science, and, in particular, the philosophical interpretation of the findings of natural science relevant to taxonomy
and evolution. 92 But one thing which has happened since the book
was written does make a difference to the implications of the first
theory's truth-namely, the correction of the error in the first
theory as originally expounded. It is, strictly speaking, not the
same theory which I then tentatively assumed to be true, and now
think I have demonstrated. I wish, therefore, to indicate briefly
how the consequences have been altered as a result of this correction. I shall limit myself to two considerations: first, the interpretation of apparently conflicting texts in Aristotle and St.
Thomas; second, an examination of the clarified notion of hierarchy in its bearings on the distinction between natural philosophy
and natural science.
(1) If there are only four proper species, then whenever Aristotle
and St. Thomas call anything other than man, brute, plant, and
91 Vd. St. Thomas Aquinas, Summa Theologica, I, 56.
•• Vd. op. cit., pp.
THE THOMIST, II,

SOLUTION OF THE PROBLEM OF SPECIES

351

body, a "species," they must be using that word in a different (and
improper) sense. It is not difficult to discover what that different
sense must be, as Aristotle uses the word in his biological works,
in which usage St. Thomas follows him, of course. The word
" species " as used of natures or concepts which are not properly
specific is strictly equivalent in significance to the word "race," as
I have been using that word to name any subordinate determination of a proper species by the possession or rejection of accidental
perfections. Other synonyms for " race " are: " sub-species," " accidental concretion," " accidental class." All of these words must be
understood as signifying either a nature which is more determinate
per accidens than a specific essence, or the truly universal concept
by which such an accidental nature, reductively in the category of
substance, is conceived. Thus, we can speak of racial, as well as
specific, natures; and of racial, as well as specific, concepts. So far
the correction of error in the first theory calls for no alteration in
the way conflicting usages of the word " species " must be interpreted.93
But the situation is different if we consider the word " genus " ;
•• The most precise mode of speech, it seems to me, would be to call proper
species "essential" and improper species "accidental"; and ·we would then also
refer to essential genera and differences, 8.'l opposed to accidental genera and differences according as they were proper and improper. The reader must be particularly
careful to understand precisely what is meant by such phrll.'les as " accidental
genus " or " accidental species," used in contrast to "essential genus " or " essential
species." By an accidental genus is not meant a gemus in one of the 9 categaries
of accident; but rathl!ll' an accidental term reductively in the categary of substance.
In short, what is meant is an accidental genus (of substance) not a genus of
accidents. If the phrll.'le " accidental genus " is rightly understood, there should be
no misunderstanding of the correlative phrll.'les: " accidental difference " or
"accidental property "-in contradistinction to essential difference and essential
property.
The pivotal points about which these sets of terms constellate are,
of course, proper and improper species, for the one is truly an essence (a true
species), and the other is truly an accidental concretion (a race or variety). For
a fuller analysis of the signification of the accidental terms related to improper
species (analogous to the four predicables which are ll.'lsociated with proper species
as a fifth predicable), vd. Part VI, Section 19, infra, and esp. fn. 129 and 180.
For the present, it is sufficient if the reader be advised that there are linguistic
difficulties in extending and correcting the traditional discussion of the predicables;
and unless he make an effort to understand my words precisely as I intend them,
he will not understand the basic contribution of my whole analysis-the distinction
between two hierarchies, essential and accidental, .the hierarchy of species and the
hierarchy of races. Cf. fn. 58 and 79, supra.
One other point: from the point of view of biological science, and science generally,
it might have been better to use the word "variety" instead of " race " to name
improper species in the category of substance; but, unfortunately, " variety " does
not have an adjectival form, and so I have used " race " and " racial."

MORTIMER J. ADLER

for the error consisted in denying that, ontologically speaking, there
could be a common generic nature. Hence I wrongly suggested
that when St. Thomas writes, for example, " although man is of the
same genus as other animals, he is of a different species" (Summa
Theologica, I, 75, 3, ad 1), the interpretation must be that he is
saying genus only in a logical sense: 94 I now see that wherever any
term can be called a genus properly, that term signifies a real generic
nature, just as every proper specific concept signifies a real specific
nature. But, of course, there remain many other passages in which
St. Thomas treats as a genus that which is not properly so, according to the truth of the first theory; as, for example, when he
speaks of brute as a genus, and regards such terms as horse and lion
as specific.115 The rule of interpretation here differs from the rule
for interpreting the word "species" in one important respect:
the word "genus" is sometimes used to name what is properly a
species, as in the case of brute, and sometimes used to name a more
general racial type in contrast to a less general one, as, for example,
when mammal is said to be the genus of which lion and elephant
are species."96 In the latter usage, the words " genus " and " species "
together are employed to distinguish generic races from specific
races, or what might be called accidental genera from accidental
species. To read the works of Aristotle and St. Thomas in the light
of the first theory, it is necessary to keep the following verbal usages
clear: (1) "species" to name a proper species; (2) "genus" to
name a proper genus; (3) "genus" to name a proper species; (4)
" genus " and " species " to name races distinguished inter se as
more and less general classes, as less and more determinate accidental types. This last point becomes fully clear only in the light of
the sharp contrast between the essential hierarchy (of proper
genera and species) and the accidental hierarchy (of accidental
genera and species, or generic and specific races) . I turn, therefore,
to a final formulation of the types of hierarchy.
and esp. fn.
and
THE
•• Vd. The Problem of Species, pp.
II,
•• Vd. Summa Theologica, I, 50, 4, ad 1, and I, 75, 7, ad
in which it is said
that just as all things having a sensitive nature are not of one species, so neither
are all things having an intellectual nature. What is intended, obviously, is not
that ani1nal (the sensitive nature) is divided into two species, man and brute,
but rather that brute is further essentially divided .into many species. Cf. Summa
Contra Gentiles, II, 85. The comparison fails because what is signified by the
common intellectual nature of all spiritual substances is their natural genus,
whereas what is signified by the common sensitive nature of man and brute, or
even of all brutes, is their essential genius. Vd. Section 15, (2) infra.
•• In other words, no texts are found in which what is properly a genus is
called a " species," but texts can be found in which what is properly a species is
called a " genus."
THOMIST,

SOLUTION OF THE PROBLEM OF SPECIES

858

(2) The distinction between the two hierarchies represented in
Diagrams 1 and 2 is itself readily grasped. As dispositions of terms
(whether these be concepts or natures), they differ by reason of a
difference in the principles which generate the orderings: for the
order of proper species and genera proceeds from principles of
essential determination, whereas the order of specific and generic
races proceeds from principles of accidental determination. The
most appropriate way to name the two hierarchies, therefore, is to
speak of the former as an essential hierarchy (an order of essences),
and to refer to the latter as an accidental hierarchy (an order of
accidental classes) . Neither the one nor the other should be
regarded as an ontological or as a logical hierarchy exclusively, for
each is an ordering of terms which can be interpreted, in the first
intention, as signifying natures, and, in the second intention, as
signifying concepts. In the domain of essences and in the sphere of
accidental types, the modes of predication, per essentiam and per
accidens, accord with the modes of being.H
But further insight can be gained by seeing the two hierarchies
as, respectively, the work of intensive and extensive abstraction.
Regarding them now from the point of view of logic, the accidental
hierarchy consists of concepts extensively (or totally) abstracted
from singulars, whereas the essential hierarchy consists of concepts
intensively (or formally) abstracted from singulars already universalized somewhat by prior acts of total abstraction. That is
why, in constructing the accidental hierarchy, we proceed from
"" The most unfortunate consequence of my error in denying a common generic
nature was the fact that I distinguished the types of hierarchy as " logical " and
"ontological."
This unhappy language runs all through The Problem of Species.
I must ask any reader who may consult that book for detailed discussions of
points referred to by this article, to be generous enough either to overlook that
language, or to interpret it according to the correction now being made: the
hierarchy I called " ontological " is now seen to be the perfect hierarchy of
essences; viewed logically, that is the hierarchy of proper specific and generic
concepts; the hierarchy I called " logical " is now seen to be the imperfect
hierarchy of accidental classes; viewed ontologically that is the hierarchy of
specific and generic racial natures. It should be obvious that the order of essences
must be a perfect hierarchy, just as the order of accidental types must be impl'll'fect. There is no longer any need, therefore, to employ the words " perfect "
and " imperfect " when the two hierarchies are understood as essential and accidental. The imperfection of the accidental hierarchy is, of course, primarily in
its vertical axis (in which, at different levels of generality, races are ordered as
lower and higher grades of accidental being); but secondarily, there may also
be imperfection in the horizontal axis (in which races may be more or less imperfectly differentiated from one another, in contrast to the perfection of essential
differentiation).
Vd. certain passages in The Problem of Species in which I
spoke of the two hierarchies as essential and accidental; e. g., fn. 247, p. 249;
THE THoMIST, n, 269.

12

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MORTIMER J. ADLER

universal wholes by division of them into their parts. This motion
from the general to the particular corresponds to the order of
learning only when our ideas are total abstractions. 98 In contrast,
we proceed from more determinate to less determinate universals
when we construct the essential hierarchy, for this is a product of
intensive or formal abstraction, whereby we see the essential part
in the essential whole: in this case, we must know what the species
are before we can see their generic constituents in them.
The intellectual methods by which we come to understand the
disposition of natures in these two hierarchies are radically diverse.
The method of division, the procedure from whole to part as extensively abstracted, is proper only in the accidental order. The
hierarchy thus generated is potentially infinite, precisely because it
is accidental, on the part of nature, and the product of extensive
abstraction, on the part of mind. The method of discrimination,
the procedure from the whole to the part as intensively abstracted,
is proper only in the essential order; and the hierarchy thus generated is necessarily finite because it is essential, on the part of nature,
and the product of intensive abstraction, on the part of mind. 99
Cf. Summa Theologica, I, 85, 3. (Note especially ad
As we have already seen, the meanings of " genus," " difference " and " species " differ radically as these words are used in the two orders. In the accidental
order of total abstractions, the genus is simply a more general concept (in extension and comprehension), the species a less general concept (in the same way),
and the difference any accidental determinant by which the genus can be diminished in extension and increased in comprehension. In the essential order of
formal abstractions, the difference is an essential determinant, with respect to
which the species are conceived as determinate (positively and negatively), and
the genus is conceived as in the differing species because indeterminate in this
essential respect, though determinate in other essential respects which can be
found in both species.
The only point of identity between the two hierarchies lies in the fact that, in
both, generic terms are more extensive and less comprehensive than specific ones.
But the two hierarchies should not, therefore, be confused or run together as if
there were no distinction between them. It is highly unfortunate, therefore, that
most logic text-books, following the tradition of teaching in the field of minor
logic, treat terms which should be placed in an essential hierarchy, as the most
general terms at the highest level of the accidental hierarchy. Viewing proper
genera and species as if they were eztensive abstractions, this treatment commits
no formal error, for these concepts are, in extension and comprehension, the superiors
of any concepts which rightly belong in the accidental order. But when major
logic follows minor logic, not only in time, but in this mode of analysis, which is
formally correct only in minor logic, and converts any concept which is superior,
in extension and comprehension, into a genus, and its inferiors into species, the
traditional logician fails to make a basic distinction between the two hierarchies.
The confusion which results not only infects the rest of logic, but acts as an
obstacle to the discovery of the truth about natures. I shall return to this
point in Part VI, infra.
98

99

SOLUTION OF THE PROBLEM OF SPECIES

355

Now these two intellectual methods help us to define the basic
formal distinction between science and philosophy. These two
kinds of know ledge are formally the same, in so far as, studying
ens mobile, all of their concepts are abstractions of the first grade.
But they are also formally different in so far as, in studying this
same formal object, natural science works entirely by extensive
abstraction, employs only accidental definitions, and deals with
substances only under the aspect of their accidental determinations;
whereas the philosophy of nature works entirely by intensive abstraction, employs only essential definitions, and deals with substances under the aspect of their essential determinations. The
cooperative unity of science and philosophy in the study of nature
can be established because the two methods of investigation, when
they have been properly distinguished, can be well-ordered to one
another. The maxim distinguer pour unir can be fulfilled. The
achievement of this precise distinction between natural science and
natural philosophy is one of the most important consequences of
our whole discussion. 100 It explains the double usage of such words
as "genus" and "species "-appropriate, in a proper and essential
sense, to philosophical analysis, and, in an improper and accidental
sense, to scientific investigation. But most important of all, as I
shall try to show in the next part, it explains how the erroneous
theory of species originated, and why it persisted: it was due to
lack of distinction between the scientific and the philosophical
study of nature; it was, therefore, an error easily made in any
epoch, such as the ancient or mediaeval, in which the cultural
conditions for making a clear distinction between science and
philosophy had not yet matured.
10 ° Cf. The Problem of Species, Ch. XI; THE THOMIST, II,
I call attention
to the importance of this point because it is so generally supposed that the distinction between total and formal abstraction is a distinction just to be made prior
to the analysis of the three grades of abstraction, and then forgotten. On the
contrary, the distinction between total and formal abstraction occurs within the
sphere defined by each grade of abstraction: on the first grade, it separates natural
science from natural philosophy; on the second grade, it separates modern mathematics from Greek mathematics (for, as any reader of Russell's Principles of
Mathematics knows, extensive abstraction is indispensable to the logic of modern
mathematics); and on the third grade, it separates a metaphysics emptied of intuitive content from a metaphysics which sees being at the heart of concrete things.
(Cf. Maritain, Preface to Metaphysics, Lecture II.) It is also worth observing
that extensive abstraction is capable of giving us genuine knowledge of the real
on the first grade, even though it be only of accidents, whereas, on the third
grade, it gives us only an illusory metaphysics. And the problems of mathematical philosophy will never be solved until the relations of extensive and
intensive abstraction, on the second grade, are fully understood.

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MORTIMER J. ADLER

15. Before I turn to the concluding part, there are two other
minor points. I call them "minor" not because they are unimportant considerations in themselves, but because they are of minor
relevance to this discussion. The first concerns the analogical predication of proper genera and species. The second concerns the interpretation of genus and difference, as constituting the species, in the
light of a doctrine concerning matter and form as composing the
essence-essence being that which is signified by species as the real
object of definition.
(I) Words may be used equivocally, univocally, and analogically,
but concepts are only of two kinds: they are per se either univocal
or analogical concepts. All transcendental concepts, and only
transcendental concepts, are purely analogical. Because they are
analogical per se, they never function univocally, and in their analogical function, they occur primarily in judgments of proper
proportionality. Though they may occur secondarily in judgments
of attribution (for a properly proportional analogy may virtually
contain analogical attributions), 101 they can never be employed
metaphorically. That is the prerogative of univocal concepts. In
contradistinction to those concepts which are called " transcendental " because, being predicable of necessary and contingent being
(in every grade and mode), they transcend the categories (the
ten predicaments), are the concepts we call "categoreal" because
they are genera or species of substance and accident. Categoreal
concepts have two fundamental properties: (a) they have a restricted range of predicability-not of all beings, but only of some;
(b) they are primarily univocal.
But unlike transcendental concepts, which never function univocally, categoreal concepts, though their primary mode of functioning is univocal, can also function analogically. The cases in
which they function in the metaphorical or attributive modes of
analogy are so plain and simple as not to need any analysis here.
The only troublesome problem is whether categoreal concepts can
ever function analogically in the mode of proper proportionality.
Is this mode of analogical judgment the exclusive prerogative of
transcendental concepts? Regarding concepts in their primary
character, the answer must be affirmative. And transcendental
concepts have only a primary character; hence they function in only
one way: analogically. But categoreal concepts have a secondary
character, because they include transcendental as well as categoreal
notes: thus, the concept of substance, or of any species of sub101

Vd. Maritain, Lea Degres du Savoir, Appendix 2.

SOLUTION

OF THE PROBLEM OF SPECIES

357

stance, must include the note of being; similarly, the concept of
virtue must include the note of goodness, and the concept of
knowledge must include the note of truth. Therefore, any categoreal
concept, which is primarily univocal, can, by reason of implicit
transcendental notes, be secondarily predicated in the analogical
mode of proper proportionality. This analogical predication of a
strictly univocal concept is sometimes spoken of as analogy of
inequality, and sometimes it is described as analogy on the part of
the things judged, but not on the part of the concept predicated. 102
But however it is called, the analysis remains the same: a univocal
concept functions analogically (in a proportional manner) when
it functions in judgments about entities which are not identical in
grade of being; and it can function in this way only because it
contains truly transcendental notes. Though in this case, the
analogy is primarily on the part of the thing, because the concept
is primarily univocal, it can be secondarily on the part of the
concept, by reason of its implicit transcendental notes.
In the light of this analysis, we can say that every proper generic
concept is primarily univocal, and secondarily analogical when it
is predicated of species unequal in rank. So much is absolutely
clear. But it also seems possible to say that even a proper specific
concept, which is primarily univocal, may be secondarily analogical
when it is predicated either of races, unequal in their accidental
grade of being, or of individuals, in so far as each individual thing
is, ultimately, also a uniquely graded being. And if this be true,
then even racial concepts, whether generic or specific, can also be
predicated analogically, though they, like proper genera and species,
are primarily univocaJ.l 03
(2) The problem of the composition of corporeal essences requires
separate treatment. When I said in The Problem of Species that
I found difficulties in the traditional doctrine of common matter as
a component of the essence, I did not mean to imply that the matter
was in no sence involved in the object of our definitions. Even though
I spoke of identifying the essence with the substantial form, I did
not suppose that we could conceive the full nature of a corporeal
substance in terms of the form alone. To explain the points I had
102 Vd. St. Thomas, In I Sent., D. 19, q. 5, a.
ad 1. Cf. Cajetan, De Nominum Analogia, ed. by P. N. Zammit, 0. P., Rome, 1934: Cap. 1. Vd. St. Thomas,
Summa Theologica, I-II, 66, 1, ad 1. Cf. also a doctoral dissertation "Analogy,
A study in Thomistic metaphysics," done at the Institute of Mediaeval Studies
in Toronto (May, 1940), by James F. Anderson.
108 Cf. what is said on this problem of analogy in The Problem of Species, pp.
and also fn. 64, 84, 139b, 163a, and
THE THOMIST, II,

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MORTIMER J. ADLER

in mind would require an elaborate discussion of types of definition,
and their diverse objects, as well as a precise analysis of the notion
of matter as prime, as signate, as common, in relation to the distinction between the specific non-subsistent essence and the individual essence terminated by subsistence. 104 Since the points in
issue were not determinative, one way or the other, of the solution
of the problem of species/ 05 I decided to postpone that discussion
for a later work. But it is, nevertheless, possible here and now to
anticipate that later work by expressing the relationship of genus,
difference, and species in terms of matter and form. The correction
of the unfortunate denial of a common genus facilitates a metaphysical rendering of the first theory. 106
The logical intention, genus, is said to be taken from the matter;
the logical intention, difference, from the form; the genus is said to
signify the whole potentially, from the point of view of the matter
as determinable; the difference is said to signify the whole potentially, from the point of view of the form as determinative; and the
species, which is taken from the union of matter and form, signifies
the whole actually. 107 Now the generic nature of any substance
is also to be understood in terms of the substantial forms which are
virtually included by the substantial form which is a given substance's first act; and the proximate generic nature is the highest
of these virtually included forms. Hence we know that the matter
which is common to the essence of two species, and which is the
principle of the common genus, must be matter virtually formed.
But the genus is indeterminate in respects in which the species,
having that common genus proximately, are determinate; and this
indeterminacy leaves the genus determinable in two ways: by a
difference which consists in the possession of an essential perfection,
with respect to which the genus is indeterminate, and by a difference
which consists in the rejection of that same perfection. Hence, we
know that the positive difference signifies the inclusion of the virtual
form in a substantial form of higher rank; whereas the negative difference signifies the actual presence in prime matter of the same sub104 Vd. The Problem of Species, pp. 14-17,
THE THoMIST, I,
98-101. Cf. Maritain, Degres du Savoir, Appendix 4; and L. de Raeymaeker,
Metaphysica Generalis (Louvain, 1935): I, p.
106 Vd. The Problem of Species, pp. 168-176; THE THOMIST, II, 108-117.
108 As already pointed out (vd. fn. 55 supra), such metaphysical rendering is
necessary because our logical account of genus and difference has employed
privative and negative terms; although these terms signify nothing in the real,
there must be aspects of the real which support the truth of a logical analysis
.
using such terms.
107 Vd. St. Thomas, De Ente et Essentia, Ch. II.

SOLUTION OF THE PROBLEM OF SPECIES

859

stantial form which was virtual in the common matter. Thus we see
how the common matter is potentially the whole of a lower and higher
species, becoming actually that whole when the virtual substantial
form, by which common matter has some determination, is the
actual form of the lower species, or is included in the higher substantial form of the species of higher rank. And this explains how
common matter differs from prime matter: in that prime matter
is, by the remotion of all forms, absolutely indeterminate and indefinitely determinable; whereas common matter must be determinate to some extent (otherwise it could not be the principle of
this genus rather than that), and being determinate to some extent,
it is definitely determinable only by those differences which constitute
the two species, both of which the genus is potentially. Common
matter has these characteristics because, unlike prime matter, it is
not conceived by the remotion of all forms, but as virtually formed
to receive or reject a certain grade of essential perfection. Both
the reception and the rejection are actualizations of this potentiality, but not in the same way: in both cases, the matter is
actualized by a substantial form, but in the one case, that substantial form is the one proximately above the virtual form of the
common matter, and in the other case, it is that common matter's
virtual form itself become actuaJ.1°8
Finally, in the light of the foregoing, we can understand the
Thomistic distinction between what is called the" natural" and the
108 Cf.
The Problem of Species, p. 179; THE THOMIST, II, 120, wherein I
vaguely anticipated this analysis. This analysis explains the real conditions
signified by privation in the genus, as well as by the negative difference which
constitutes a species by the rejection of a perfection. For, metaphysically speaking, what is signified by the negative difference is simply the form, virtual in the
common matter, become actual as the first act of an existing substance; and what
is signified by the indeterminacy (privation of determination) in the genus is the
mere virtuality of that form, capable of either being included in a form of higher
rank as the first act of an existing substance (higher species) or of being itself
the first act of an existing substance (lower species) . And, of course, the genus
never signifies any actually existing nature; it always signifies a potential nature;
and so the common matter (matter conceived as under a virtual form) exists
only in the specific essence, where the same matter is under an actual form, the
principle of the difference. Hence when St. Thomas says that " specific difference is derived from difference of form; nor does every difference of form necessarily imply a diversity of genus" (Summa Theologica, I, 75, 8, ad 1), the statement can be interpreted to mean that, as between two existing substances, proximately differing as to specific nature, there is only a difference in their substantial forms. That such substances do not differ in genus follows from the
fact that the potential whole of their diverse essences can be conceived in terms
of the same common matter, i. e., matter under the same virtual form.

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MORTIMER ;r. ADLER

"logical " genus. 109 The natural genus of a substance is to be
understood in terms of its ultimate metaphysical composition:
either as a composition of form and existence (angels) or as a
composition of prime matter and substantial form (corporeal
things) _no In contrast, the logical genus of two specifically differing
substances, belonging to the same natural genus, is the intention
taken from the common matter in their essences; whereas the logical
genus of two substances, belonging to different natural genera, is a
purely logical intention, purely logical in the sense that it can have
no first intentional significance whatsoever, for it can signify no
common matter, as the principle of a generic nature capable of
specific differentiation. Hence St. Thomas calls this latter genus
"logical " to distinguish it from all other generic concepts, which
can be both first and second intentions. Strictly speaking (since
the celestial bodies do not differ in matter from sub-lunary bodies),
there is only one "logical genus " (of the type described) in the
category of substance-and that is substance itself. But within the
natural genus of corporeal, as distinguished from the natural genus
of spiritual, substances, it still remains important to discriminate
between the natural genus, which is taken from the prime matter
and, as such, is common to all the corporeal species, and the
essential genus, the one mentioned in a definition, which is taken
from the common matter and, as such, is common proximately only
to two species (or to a genus of higher rank and a species) .111
VI.

CONCLUSION:

HISTORICAL

HYPOTHESIS

16. This concluding part is written for those readers who have
found, in the foregoing analysis and arguments, the demonstration
109 Vd. Summa
Theologica, I, 88,
ad 4, wherein St. Thomas says that
spiritual and corporeal substances are in the same genus, substance, logically, but
not naturally; and ibid., I, 66,
ad
wherein St. Thomas says that earthly and
celestial bodies are in the same genus, body, logically, but not naturally. Cf. De
Trin.
IV,
where the same points are made even more explicitly: to the
effect that things are said to be in different natural genera, according to three
conditions: (1) because no matter at all enters into their natures, i. e., the
angels; (2) because the matter which enters their natures is incorruptible, i. e., the
celestial bodies; (8) because. the matter which enters their natures is corruptible,
i. e., the sublunary bodies. Now, if we omit the second case, as the metaphysical
analysis of a matter contrary to fad, there remains only one distinction as to
natural genus: between substances having no matter, and substances composite
of prime matter and substantial form.
110 Vd. fn. 109 supra.
1.u Cf. The Problem of Species, pp. 172-178; THE THoMrsr, II, 114-15. The
points just made have a bearing on the analysis, which I propose to do later,
dealing with the types of definition in relation to the notions of matter and form
as composing essences and substances.

SOLUTION OF THE PROBLEM OF SPECIES

361

of a truth and the expose of a false doctrine. For they, as I, must
wonder how it could have happened, how such mistaken views, in
both logic and the philosophy of nature, could have arisen and have
persisted for so long. For them I should like to propose an explanation-an historical hypothesis which locates the crucial mistakes in
the work of Aristotle. This being their origin, it is not difficult to
account for their persistence in the tradition of European philosophy.
But first it is necessary to define precisely the character of the
mistake being accounted for. It does not consist, as might be supposed, in affirming the second theory of species as contradicting the
first on all important points. In fact, the second theory has probably
never been held by anyone in so extreme a form. The mistake must
rather be described as a failure to see the whole truth which is
contained in two related analyses-on the one hand, the analysis
of proper species and genera as disposed in a perfect hierarchy
(Diagram 1); and, on the other hand, the analysis of accidental
classes (improperly regarded as species and genera) as these are
disposed in an extensive hierarchy
There is absolutely
nothing incompatible between these two analyses. The two hierarchies of terms which they present can be perfectly ordered to one
another, but only on one condition, namely, that the two analyses
be kept distinct, that the two hierarchies be understood to be as
basically different as essence and accident are. It is precisely this
condition which history shows. has been violated. When things
which should be kept distinct a·re not rightly distinguished, confussion and disorder must result.
Such confusion and disorder permeate any view of species and
genera which runs the two hierarchies together. This view is, in a
sense, the second theory of species, not as opposing the first theory
in every respect, but as trying to include some of the points of the
first theory while at the same time trying to hold on to contradictory elements in the divergent account. The confused view can
be easily recognized in every one of its historical occurrences, for it
bears a telltale mark. The sign is a double affirmation which cannot
be made consistently: (I) that man is a rational animal, and
that brute is a genus. The mistaken view is thus seen to be the
second theory, as including the first in so far as the real definition
of man is affirmed and real definitions of such " genera " as brute
and plant are admitted, but also as diverging from the first in falsely
regarding brute and plant as genera, and hence holding to a larger
number of species. Such a view must necessarily fail to see the
distinction between the two hierarchies and must necessarily confuse two quite distinct analyses: of proper species and genera, on

MORTIMER J. ADLER

the one hand, and of races (improper species and genera), on the
other.112
My historical hypothesis is that the mistaken view had its origin
in a fundamental error and inadequacy in Aristotle's logical treatises
(especially in the Posterior Analytics and the Topics). That error
and inadequacy has persisted throughout the whole history of
Aristotelian (which means" scholastic") logic. But, unfortunately,
because of the way Aristotle's logical writings dominated mediaeval
thought, and exercised an undue influence over speculations about
the nature of things, the error spread to and infected what we now
call the philosophy of nature.U 3 Hence, there are two steps in my
historical explanation, In the first, I shall try to account for the
origin of the error in logic, at the time of Aristotle. In the second,
I shall try to account for the spread of this error, in post-Aristotelian
thought, to the domain of knowledge about the corporeal world.
There is one other preliminary observation I should like to make
at once, in order to prevent misunderstanding and emotional unpleasantness. I realize that the name of Aristotle is sacrosanct, and
deservedly so, in grateful tribute to an incomparable, original mind.
But Aristotle was human, and his humanity places two limitations
upon his work: (I) it is always the product of a finite mind (not
112 In The Problem of Species, I referred to this view as the second theory of
species, because I then thought there were two possible theories in opposition.
Now that the truth of the first theory has been demonstrated, there is no possible
second theory. I shall henceforth refer, therefore, to the mistaken view (i. e.,
the view which confuses analyses that should be kept distinct and which, because
of this confusion, fails to give au orderly and adequate account of the whole
truth.)
As I read traditional and contemporary texts, I cannot help feeling that the
mistaken view was and still is widely prevalent. I have presented the evidence
for this feeling in The Problem of Species: vd. Ch. V and X; THE THoMisT,
I, 381; II, 237. Others may be able to interpret the texts differently, but I
seriously doubt whether they can show that the true and adequate theory (not
only true with respect to proper species and genera, but adequate in the sense
that it orders the accidental to the essential hierarchy in terms of a clear distinction) is the dominant view in philosophia perennis. I would go further and say
that I doubt whether the true and adequate theory could have been completely
formulated until the modem period. The mistaken view, as I shall now try to
show, is au historical phenomenon, thoroughly explicable and condonable in the
light of the historic cultural conditions of ancient and mediaeval thought. If
that is the case, then the true and adequate theory. can be completely Aristotelian
and Thomistic even if, as a matter of historic fact, it was never completely known
to Aristotle or St. Thomas.
118 I say " we now call " because until modem times there was no distinction
within the sphere of physics (defined by the first grade abstraction) between
the science and philosophy of nature. This very fact is basic to my explanation
of the error, its origin and persistence.

SOLUTION OF, THE PROBLEM OF SPECIES

868

only finite, but also of the lowest order of created intelligences);
(2) it is always the product of an historically located mind-a mind
bounded in its outlook by definite cultural conditions. It is not
sufficient to admit that, like Homer, Aristotle also sometimes nods.
That concession is too often made only with respect to unimportant
inaccuracies about matters of observable fact. A just recognition
of the inescapable limitations which humanity imposes on Aristotle's, or any other man's, work requires us to admit that Aristotle
might have erred on major points of philosophical doctrine.
Now, it is no longer unheard of to say that Aristotle, the author
of the Metaphysics and really the founder of that study, is far from
perfect as a metaphysician.U 4 Lacking, and in a sense even opposing,
a doctrine of creation, Aristotle could not know the basic distinction
between necessary and contingent being in terms of essence and
existence as identical in God and really distinct in creatures. As
a result, his understanding of the analogy of being was crucially
defective. His supposed proofs for the existence of God were
nullified by his supposed proofs for the eternity of the world. His
theory of matter was sufficiently imprecise to permit some of his
followers to commit the error about a plurality of substantial forms;
and his account of the human soul not only lacked a clear argument for its incorruptibility, but also, in the context of his doctrines
about God and eternity, permitted commentators to discover in his
writings warrant for false notions about the unity of the intellect,
active or possible. Now, with respect to all of this, Thomists agree
upon three things: first, that the points I have called errors and
inadequacies are rightly so named; second, that St. Thomas, as an
interpreter of Aristotle, avoided these errors and corrected these
inadequacies; and third, that St. Thomas, unlike Avicenna, Averroes,
and others, was able to do so because he approached these philosophical questions in the light of Christian faith. In this one fact
lies the essential distinction between the capacity of the pagan
Aristotle and his greatest Christian disciple. It is not that St.
Thomas, as a mere man, had a greater intellect : on the merely
human level, the greatness of the discoverer surpasses the greatness
of the expositor. It is rather that St. Thomas was a Christian, and
possessed through God's grace a light by which to see things that
must always have remained in the dark for Aristotle, no matter
how magnificent his natural aptitudes for learning the truth. In
this one fact, I say, lies the essential superiority of Christian over
Greek philosophy. And when we understand the sources of this
110 Vd. E. Gilson, The Spi.rit of Mediaeval Philosophy, New York, 1936: Ch.
I-V; and A. C. Pegis, St. Thomas and the Greeks, Milwaukee, 1939.

364

MORTIMER J. ADLER

superiority, we can, without any condescension whatsoever, excuse
Aristotle for faults which belong to him as a Greek-which follow
from his human limitations as living in a certain way at a certain
time, as a pagan in a pre-Christian eraP 5
The superiority of Christian philosophy is primarily in the sphere
of metaphysics, and especially on the boundary line between natural
and sacred theology. There is no reason for a similar superiority
of Christian thought in the spheres of physics and logic. We know,
in fact, that such superiority does not exist. I do not mean that
Christian commentators fail to improve upon Aristotle in these
fields; but the improvements are entirely in matters of systematic
detail, in making latent implications explicit. I mean that, in the
fields of physics and logic, Christian commentators fail to do what
they do in metaphysics. They fail to rectify the basic errors and
correct the essential inadequacies in Aristotelian logic and physics.
And the reason for this failure is like the reason for the superiority
of Christian thought in metaphysics. Just as in the latter case, an
historic fact of profound cultural significance-the fact of Christian
revelation-explains the superiority, so in the former case, another
historic fact, also of great cultural significance, explains the failure.
As the occurrence of Christian revelation separates the mediaeval
from the ancient world into two distinct cultures, in which human
thought has different reaches, so the occurrence of scientiii.c investigation as an autonomous and self-conscious enterprise separates
the modern world from both ancient and mediaeval eras taken
together, as a world in which altered cultural conditions make
possible new attainments of thought. And just as the characteristic
superiority of Christian, or mediaeval, philosophy was in the sphere
of metaphysics because its problems were most illuminated by faith,
so the characteristic superiority of modern philosophy can be in the
sphere of logic and the philosophy of nature because their problems
are most altered in perspective by the separation of science from
philosophy .116
115 The notion
of Christian philosophy, to which I here subscribe, has two
points in it: first, that the light of faith was, in fact, historically indispensable
for the discovery of certain truths which, as such, belong to the domain of natural
reason, and hence are strictly philosophical, not theological; second, that the light
of faith is not similarly indispensable for the communication of these same truths,
once they have been discovered; or, in other words, that whereas ancient pagans
could not have discovered them, modern pagans can learn them from the teachings of Christian philosophers. If all (pagan) truth belongs to Christianity, as the
spoils of the Egyptians belonged to the Jews, so all (Christian) truth belongs to
men in general, in so far as these truths are strictly evident or demonstrable in
the light of natural reason.
118 Cf. What Man Has Made of Man, New York, 1937: Epilogue, pp. !!35-!!44;

SOLUTION OF THE PROBLEM OF SPECIES

365

It should be noted that it is the separation of science from
philosophy which I emphasize primarily, not the actual accretions
in knowledge about nature which have been gained by scientific
work. The latter, of course, do play an important role in relation
to a sound development ofthe philosophy of nature; 117 but it is the
understanding of an essential distinction between science and
philosophy (as two methods of knowing, having distinct formal
objects within the sphere defined by the first grade of abstraction)
which is absolutely indispensable to a rectification of ancient and
mediaeval logic-especially to the extent that major logic tries to
give a formal account of the concepts, judgments, and reasonings
productive of " scientific " knowledge. I put the word " scientific "
in quotation marks because of an ambiguity we now see, which the
ancients and mediaevals did not see. They used the word " scientific " without distinction for two sorts of knowledge of nature
which we now distinguish as philosophical and scientific. If our
distinction is right and justified, then it follows necessarily that the
ancient conception of " scientia " was a confused notion-certainly
so on the first grade of abstraction. 118 And it follows with equal
necessity that Aristotle, working with a confused, i. e., inadequately
distinguished, notion of" scientia," could not possibly have avoided
basic errors or profound inadequacies in his logical treatises,
especially those, such as the Posterior Analytics and parts of the
Topics, concerned with the definitions to be e:mployed in "science,"
the modes of demonstration to be used, the induction of principles,
and the general theory of "scientific" taxonomy. I say, therefore,
that Aristotle's errors and inadequacies in logic are as excusable as
his errors in metaphysics, though the reason for his making them
and our grounds for excusing him-without condescension in either
case-are different. 119
also "A Dialectic of Morals," Part I, in The Review of Politics, ill, 1 (January,
1941): pp. 3-13.
117 Vd. J. :!\'Iaritain, The Degrees of Knowledge, New York, 1938: Ch. I and III;
pp. 3-69; also his Science and Wisdom, New York, 1940: Part I, esp. pp. 3-69; also
his La Philosophie de la Nature, Paris, 1935.
118 As I have already pointed out, the distinction between science and philosophy is of most importance on the first grade of abstraction; of some importance
with respect to mathematical objects; and of least importance with respect to
knowledge of being, where science, in the modern sense, makes and can make
fewest pretensions. Vd. fn. 100 supra. For M. Maritain's most recent discussions
of the essential distinction between philosophy and science, vd. Scholasticism and
Politics, New York, 1940: Ch. 2; and Science, PhilQsophy and Religion, A Symposium, New York, 1941: pp. 162-183.
110 In one sense, the reasons are alike: the cultural limitations
of Greek thought.
But, in another sense, the reasons are different in that, with respect to logic and

366

MORTIMER J . .ADLER

I shall not offer here a general critique of the Organon. 120 I wish
to deal only with its theory of " scientific " taxonomy, with the
analysis of definitions and the account of the " predicables," for
these are the only matters relevant to my historical hypothesis
about the origin of the mistaken view of species. I turn, therefore,
at once to a brief exposition of the two steps I have already
mentioned.
17. The first step is to see that Aristotle's logical account of
species, genera, etc., was colored by the "scientific" method which
he himself applied in the classification of living things, a method
exhibited in his Historia Animalium, and explicitly set forth in the
first book of his De Partibus Animalium. 121 That method is the
method of extensive abstraction. It can yield only accidental classifications, not essential ones. The hierarchy of classes which such
taxonomy generates can be nothing other than the extensive hierarchy of races (of improper, or accidental, species and genera);
and hence the resultant theory of specification, the theory of the
genus and of its mode of differentiation by positive determinations
rooted in distinct (accidental) perfections, is only one of two possible accounts of species, genera, and differences. There is nothing
wrong with this account in itself, for it is the correct account of
accidental classification. But when this account is taken to be the
whole truth, or when it is taken to be an account of essential classification, because of failure to distinguish between proper and improper species (i. e., species and races), then serious error results.
In De Partibus Animalium, I, 2-4, Aristotle attacks the method
physics, the cultural limitations of Greek thought are shared equally by mediaeval
philosophy. Should there be Thomists willing to admit .Aristotle's limitations in
metaphysics, but not willing to admit similar limitations in logic and physics, it
would look as if, in the latter case, they were loath to admit the limitations of St.
Thomas about matters in which his faults are as appropriate historically, and as
excusable, as .Aristotle's . .And this would be a fault in modem Thomism much worse
than the errors in logic and physics under discussion; it would be the fault which was
universal among the decadent scholastics of the 15th and 16th centuries and which
has, ever since, made " scholasticism " such a bad name. Vd. the encyclical
Aeterni Patris: " If there be in the scholastic doctors any excessive subtlety of
inquiry, any inconsiderable teaching, anything not consistent with the ascertained
conclusions of a later generation, anything in any way i:Q:J.probable, we have no
mind to hold that up for imitation."
120 I have indicated some other points of criticism in The Problem of Species
(pp.
THE THOMIST, II, 264-66, but a general critique would require a
long work devoted to nothing else. I hope to do that later.
121 Though the taxonomic problem is somewhat different in the case of inanimate things, the method .Aristotle employed in the case of elements and mixtures
is formally the same. Vd. De Oaelo, ill, 8-8; De Gtmeratione et Oorrupticme,
II, 1-5.

SOLUTION OF THE PROBLEM OF SPECIES

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of dichotomous division, and the use of privative and negative
terms. The right method to be followed in specifying animals, he
tells us, makes manifold divisions within a genus; and to do this
we must not only rely mainly on positive differentiae, but we must
differentiate by means of many determinations taken in conjunCtion,
rather than singly. 122 And he concludes this whole discussion with
the remark:
We have now touched upon the canons for criticizing the method of
natural science, and have considered what is the most systematic and easy
course of investigation; we have also dealt with division, and the mode of
conducting it so as best to attain the ends of science, and have shown why
dichotomy is either impracticable or inefficacious for its professed purposes.
(De Partibus Animalium, I, 4, 644b16-19) .
122 " Some writers propose to reach the definitions of the ultimate
forms of
animal life by bipartite division; but this method is often difficult and often
impractical" (op. cit., 642b 5). "Privative terms inevitably form one branch
of a dichotomous division, . . . but privative terms in their character of privatives
admit of no subdivision; . . . yet a generic differentia must be subdivisible, for
otherwise what makes it generic rather than specific" (ibid., 642b 21-26) . "Even
with differentiae capable of this specific division it is difficult enough to make
classifications so that each animal shall be comprehended in one sub,.division and
not in more then one; but far more difficult, nay impossible, is it to do this, if
we start with a dichotomy into two contradictories" (ibid., 642b 8-85). "As we
said then, we must define by a multitude of differentiae " (ibid., 648b 25) . "It
is impossible that a single differentia, either by itself or with its antecedents, shall
express the whole essence of a species " (ibid., 648b 80) . "It is impossible then
to reach any of the ultimate animal forms by dichotomous division " (ibid.,
644• 10). All these passages, especially in the complete context of the chapters
from which they are taken, plainly say that the method of differentiation by which
we divided animal into two ultimate species, man and bTUte (the non-rational
sensitive into the rational sensitive and irrational sensitive), will not apply when
we try to divide bTUte, as a genus, into subordinate forms of " animal life."
Aristotle is quite right in saying this, and he has revealed the precise difficulties
we met with when we tried to use such terms as mobile and immobile, vetebrate
and invertebrate, or oviparous and viviparous, as single differentia. Vd. fn. 72
supra. Aristotle is only wrong in not realizing that the method which he is
rejecting is the right method for essential classification, whereas the method he
says should be employed in its place is the right method only for accidental classification. The "ultimate forms of animal life" to be reached by this method
must be races; they cannot be proper species. On the use of manifold differentiae
as an essential point in the second theory of species, vd. The Problem of Species,
PP· 76, 122, 151-155, 188-195; THE THoMisT, I, 262, 420; n, 92-96, 129-186. As
I have pointed out (vd. footnote 57, supra), the use of manifold determinations to
differentiate one (improper) species from another causes the extensive hierarchy
to be imperfect in still another way: not only are there generic interruptions in the
gradation of such species (from lower to higher in the scale of being), but one
species may be higher than another in certain respects (some of its manifold
determinations) and lower than that other in other respects. The extensive

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MORTIMER J. ADLER

He should have gone further. He should have said that the method
of dichotomous division, using privative and negative terms, is more
than impracticable and inefficacious. It is, strictly speaking, an
impossible method for making significant divisions of brute animal
life, precisely because brute is a proper species, and any further
division of it must employ accidental determinations, positive and
manifold. He would have spoken the whole truth here, if he had
known that his own " scientific" works were scientific and not
philosophical, if he had known that the method he was proposing is
the method of science and not of philosophy. But such distinctions
were totally unknown to Aristotle. His own references to De Anima
in De Partibus Animalium show that he saw no difference between
the method of the two works. It never occurred to him, therefore,
to suspect that his classification of three souls, and his consequent
definition of three species of living things, followed a radically
different method, depending on a different theory of the genus, and
of its differentiation by positive and negative determinations rooted
in one and the same (essential) perfection. 123
Failing to make these necessary discriminations, Aristotle confused two different logical accounts of species, genus, and difference.
Whereas he should have given us an analysis of two quite different
hierarchies of terms, each with its own appropriate principles, he
gave us only one analysis in the Posterior Analytics and the Topics.
That analysis cannot help being both erroneous and inadequate, in
so far as it mixes principles which should be separated, and omits
distinctions which should be developed. Seeing this is the first step
in my historical hypothesis, the one which explains the origin of the
mistaken view of species-the ultimate cause of the error in Aristotle's logic being his ignorance of the distinction between the
science and philosophy of nature. 124
18. The second step is to see that Aristotle's works contained a
theory of genus, difference, and species, which diverged radically
(accidental) hierarchy is thus multilinear, in contrast to the unilinearity of the
perfect (essential) hierarchy. Races cannot be well-ordered, as species are.
128 The only evidence of any suspicion that the two accounts could not be
run together is the' number of times in which Aristotle uses an accidental definition of man (as featherless biped)' instead of ratiiJ'lUll animal, which he must
have realized was a definition absolutely different from ilie sort capable of being
achieved by the " scientific" method he is proposing.
1 .. The cause here is plainly proportionate
to the effect. Just as "scierntia"
for Aristotle included both science and philosophy in an inchoate state, so his
logical analysis of species, genus, and difference, included, in an inchoate state,
the principles of both essential and accidental classification. When that which is
in an inchoate state is regarded as if it were not so, things which can be fully
distinguished and well-ordered are treated in a confused and disorderly manner.

SOLUTION OF THE PROBLEM OF SPECIES

369

from the one given in the De Partibus Animalium, and applied in
the Historia Animalium. This other theory conceives specific
natures as grades of being, ordered in a perfect hierarchy. Its principles are indicated, though not explicity set forth, in the Metaphysics, and they are exemplified in the classification of souls in the
De Anima. 126 My point here is not the one I have made before,
namely, that Aristotle's logic fails to discriminate between the
account which must be given of philosophical as opposed to scientific classification. Rather it is that Aristotle, as a philosopher of
nature, failed to grasp the significance of his own analysis of three
kinds of soul, failed to see that this analysis required him to affirm
explicitly that there were only three proper species of living thing,
failed to realize, in consequence, that all the subordinate forms of
brute and plant must be accidental types. 126 ·
The combination of error in logic with error in the philosophy of
nature had grave historical consequences. For centuries, the influence of Aristotle's thought upon the Latin west came by way of
commentaries on his logic, chiefly Porphyry's lsagoge and Boethius'
gloss thereon. The lsagoge was intended as an introduction to the
Categories, but Porphyry followed that totally unAristotelian prouo The theory which can be found in Metaphysics, VTII, X .• and in De Anima,
II, 3, can also be found in similar portions of St. Thomas's work: in De Ente et
Essentia, Ch. II, and in the Treatise on Man in the Summa Theologica (1, 75-77).
By " similar portions " I mean passages which are strictly philosophical, (not
scientific) in character. The Metaphysics is, of course, wholly philosophical, as
is De Ente; but the De Anima (and the Treatise on Man) contains passages of
both sorts. Yet in the part of the De Anima referred to, the concern is with
species as grades of being, and the method by which Aristotle distinguished three
kinds of souls (and thus defined three species of living thing) is clearly the method
of intensive or formal abstraction,
It is the only method by which essential
classifications can be made. It is the method of philosophy, as opposed to the
method of science, in the study of nature. And the hierarchy which is. discovered
by this method is necessarily perfect, for it employs principles of differentiation
which are appropriate to ordering things according to grade of being. But the
principles here referred to are nowhere explicitly recognized in the Organon, as
radically different from the principles underlying the method of the De Partibus
Animalium and the Historia Animalium. If anything, the Organon tends to
express the latter set of principles rather than the former, though it does so
unwittingly, largely because of the illustrations used.
126 In the De Anima itself there are passages which reveal these failures, passages
which definitely speak of many species of irrational animal. Vd. St. Thomas, In
De Anima, II, 5, # !294; II, 7, # 1!14. There are similar passages.in the Treatise
on Man, vd. Summa Theologica, i, 75, 7, ad !2; 76, 3; cf. QQ. Disp. de Anima,
Q. 1, A. 7. The ultimate cause of these failures on Aristotle's part is the same
as the cause of the defects in his logic, namely, ignorance of the essential distinction between philosophy and science in the study of nature. Hence we cannot
read the De Anima or the Treatise on Man, as if they were purely philosophical
treatments, for admixtures of science penetrate their discussion of specific natures.

13

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MORTIMER J. ADLER

cedure of using a discussion of the problems to be found in the Topics,
as a way of showing how one passed from summum genus to infima
species in the various predicaments, chiefly substance. Porphyry
and Boethius were themselves primarily concerned about the then
incipient " problem of universals." Furthermore, they were neoPlatonists misusing Aristotle's logical distinctions to describe the
order of nature. When to all these factors is added the crucial fact
that these writers fail to see the essential distinction, in object or
method, between the philosophical and scientific parts of Aristotelian teaching, it is not difficult to unearth the seeds from which
sprang the Tree of Porphyry, that noxious growth which cast its
distorting shadows over the study of nature for many centuries.
Porphyry had somehow gathered the essential division of corporeal
substances into body, plant, brute, man.-probably from indirect
acquaintance with the De Anima. With this he mixed his own
theory of the five predicables (derived, as I shall show, from his
misreading of the Topics, which reflects in a confused way both
the philosophical taxonomy of the De Anima and the scientific
method of the De Partibus Animalium, though the latter predominates. The damage was thus done. Boethius merely canonized the
errors. 127
This second step in my historical hypothesis explains how the
original error in Aristotle's Organon came to have such great currency in the tradition of Aristotelian thought. The Tree of Porphyry, or its implications, still prevails in scholastic textbooks of
logic. In addition, this second step explains not only the persistence
of the mistaken view, but also its spread from logic to the philosophy
of nature, due to the fact that the Porphyrian diagram was given
an uncritical ontological interpretation: as if anything a logician
referred to as a species was properly a species; as if the decision as
to 1vhich concepts are properly specific could be made in logic.127 "
12 • The Tree of Porphyry
epitomizes the confusions latent in Aristotle, by
explicitly going from essential to accidental distinctions without recognizing any
difference of principle whatsoever. The Tree is nothing but a schema which
combines our Diagrams 1 and !! by running them together as if they were both
expressions of the same set of principles.
.
1 ... The logician qua logician is competent only to state the formal criteria for
distinguishing proper from improper species (as, e. g., in terms of mode of differentiation); but only the philosopher of nature can say, in the light of his knowledge
of man and of inferior beings, which concepts are properly specific, i. e., which
natures are properly conceived as specific; similarly, only the natural scientist can
say, in the light of all his empirical data, which racial (improperly specific)
concepts are generic, and which specific. On this last point, vd. fn. 180, infra.
For the logician to proceed as if he were competent to make these material discriminations involves him in an uncritical interpretation of his own logical, or

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Instead of cutting down the Tree of Porphyry, and exposing the
field of nature to the light of day, the philosophy of nature has for
centuries been content to view things under the distortion of its
shadows. Perhaps such heroic action was impossible in the middle
ages, since the only instrument capable of cutting the Tree down is
the sharp edge of the distinction between philosophy and science.
It is unfair to Porphyry and Boethius, however, to charge them
with being more than accessories in either the perpetuation or the
spread of the mistaken view. If they had never existed, and no
commentaries on Aristotle had ever been written until, in the thirteenth century, all his works were available for study, the mistaken
view would have still prevailed in the tradition of Aristotelian
thought, because it existed in Aristotle's own work, both in his
logic and in his "philosophy of nature "; and because no thirteenth.
century commentator could have corrected the errors for exactly the
same reason that Aristotle committed them-a failure to understand
the distinction between science and philosophy in the study of nature ..
The point is not that the errors are deeply hidden from view. On
the contrary, they would seem to be almost painfully evident to
anyone who tries to connect his reading of the Metaphysics and De
Anima, on the one hand, with his reading of the Historia Animalium,
and the De Partibus Animalium, on the other ·(and both in relation
to the Organon). Yet until the reason for the difference between
what is said about species in these two groups of works is itself
understood, the light is not available whereby the reader can discover these errors.
There is one further point about the importance of Porphyry
in this story. With regard to the matters here being discussed, the
tradition of Aristotelian logic, especially the scholastic tradition,
is strictly not Aristotelian but Porphyrian. The point is not the one
now generally recognized, namely, that Porphyry enumerated five
predicables, whereas Aristotle is supposed to have named only four.
The difference goes much deeper than that, for the whole notion of
a set of predicables is Porphyry's own invention. Strictly speaking,
there is no discussion of predicables anywhere in the Organon, cer..J
tainly not in the Topics. Let me explain.
In the Topics (especially I, 4-9), Aristotle is concerned with the
inductive process of getting knowledge about" species "-the object
of " scientific " knowledge. He there makes a fourfold division of
formal, criteria, for in doing so he misuses these criteria. ·Cl. fn. 87, supra. This
distinction between the spheres of logic and ontology with respect to the problem
of species is indispensable to reaching a true view of these matters; violatiol\ of
it resulted in the Porphyrian errors.

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MORTIMER .T. ADLER

problems: first, a twofold division of problems into those concerning essential and those concerning accidental matters; and then a
further division of the essential into problems concerning genera
and definitions, and of the non-essential into problems concerning
properties and accidents. 128 These four (genus, definition, property,
accident) are the subjeCts (topics) about which argument takes
place in the discussion of " species." They are also the four loci of
inductive problems in the " scientific" investigation of " species."
Aristotle is not at all concerned with a classification of universals
into fundamental types, according as they are differently predicable
of first substances. If the word " predicable " signifies a universal
so considered, then Aristotle gives no account of the predicables.
His analysis of the four problems (topics of discussion and inquiry)
concerning " species " permits a classification of universal terms
only in so far as universals ·can be distinguished as they enter into
the solution of one or another of these problems. But if such
distinction be made in Aristotle's own context, genus and definition
must be mentioned, whereas species and difference must be excluded.
This sharp divergence between Aristotle's four loci of problems
(genus, definition, property, accident) and Porphyry's five predicables (genus, difference, species, property, accident) is intelligible
only if we see that Porphyry was concerned with a totally different
phase of logical inquiry. He was writing an introduction to the
Categories and was therefore concerned, not with the problems of
" scientific " research and discussion about " species," but with the
theory of predication itself. Hence he properly took, as a fundamental canon, Aristotle's own basic maxim that all predication is
of first substances. But what different modes of predication are
there, when first substances are taken as subjects? Aristotle proposes a fourfold classification of terms (neither predicable nor
inherent, predicable but not inherent, inherent but not predicable,
both predicable and inherent) / 28 " which underlies the distinction
between predication per essentiam and predication per accidens; but
Porphyry must have perceived verbal connections, between distinctinctions made in the Categories and those made in the Topics,
which led him to convert the fourfold division of problems (as in
the Topics) into a fivefold classification of the types of universals
which are predicable of first substances. Hence, the fact that he
employed material from the Topics in writing an introduction to
the Categories caused Porphyry to transform the topical analysis
of problems (concerning second substances, i. e., " species ") into
128

128 "

Op. cit., 10lbl8 ff., 103b 15-37; cf. Categories, s• !t!t, and Prior A-rwlytics, 48b.
Vd. Categories, !t.

SOLUTION OF THE PROBLEM OF SPECIES

373

his own, quite novel, analysis of predicables (having first substances
as their subjects). The change in the
of terms being classified, and the change in the precise character of those terms, thus
becomes thoroughly intelligible, for just as species and difference
should not be mentioned when one is concerned, as Aristotle was,
with a division of the problems about " species," so species and
difference should be named, and definition omitted, when one is
concerned, as Porphyry was, with a division of all universal terms,
predicable of first substances, into their fundamental types.
It can be said against Porphyry that he misread Aristotle, especially the Topics; but it can be said for him that he discovered a
genuine logical problem (how many types of universal can be
predicated of first substances?) which Aristotle failed to consider.
Furthermore, this problem is thoroughly proper within the essential
scope of Aristotelian logic, even if Aristotle himself did not consider
it, and even if it was discovered by a neo-Platonist through a
characteristically neo-Platonic misunderstanding of the Organon.
In any case, there is no question that the mediaeval, and modern
scholastic, tradition in logic is Porphyrian, in so far as it follows
Porphyry's fivefold classification of predicables, rather than Aristotle's own fourfold classification of problems. 128 b
These facts do not alter the historical hypothesis here being
suggested-that the mistaken theory of species arises from a fundamental error in Aristotle's logic, and persists through the Porphyrian
transformation. If Aristotle had separated proper from improper
species-true species as the objects of philosophical analysis, from
races as the objects of scientific investigation-then Porphyry, in
following Aristotle, would have enumerated at least six predicables,
instead of five, for in transforming Aristotle's discussion into an
account of universals as predicable of first substances, he would
have been forced, in the interest of exhaustive analysis, to name
race as one type of universal predicate.
19. I should like, therefore, to complete this historical hypothesis
by stating briefly how Aristotelian logic would have to be reformed,
in view of the truth about species. I do this to suggest positively
what an Aristotelian (or, shall I say, Porphyrian) account of definitio:p. and of the predicables would have been like, had Aristotle
fully recognized the distinction between an intensive, or essential,
usb Vd. Summa TotiUB Logicae Aristotelis (classified by Mandonnet as spurious
among the Opuscula of St. Thomas): Tractate I; cf. Averroes, Expositio Media in
octo libros Topicorum, Lib. I; Maimonides, Guide for the Perplexed, New York,
Ch. 51, 52.

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MORTIMER J. ADLER

and an extensive, or accidental, hierarchy. By contrast this should
make the error in traditional logic very clear.
The correction can be stated in a single sentence. In the exposition of the predicables (the ultimate logical categories for classifying
universal predicates), the logical concept, race, must be added to
the traditional five: genus, difference, species, property and
accident. 128 c Race is a logical concept, just as the others are; it is
a second intention; it is predicable of other concepts which are first
intentions; and, as predicated of these concepts, it explicates the
intentionality with which they, in turn, are predicated of first substances. The indispensability of this logical concept (race) can be
seen from the fact that without it we can give no account of a whole
class of universal terms-all the terms which have these two characusc To put this point in strictly Aristotelian terms I should have to say, not that
Aristotle omitted the concept of race from his list of predicables, but that Aristotle
failed to distinguish between species and race as, respectively, the focus of philosophical and scientific problems. Had he made this distinction, he would then
have set forth two sets of four problems each: four problems concerning species,
and four problems concerning race; and the two sets would have been analogous,
as essential problems about genus, definition, property, and accident, on the one
hand, and accidental problems about genus, definition property, and accident, on
the other. With sufficient evidence before his eyes (the perfect hierarchy of species
in the De Anima and the accidental classification of animal types in the Historia
Animalium), Aristotle could not see what any of us can see today-what contemporary scholastics see when they feel obliged to distinguish between " natural "
and " systematic " species, what Maritain calls our attention to when he cautions
ns to distinguish between "proper" and " improper" species. We see what
Aristotle could not, because we cannot help being aware of the fundamental difference in method underlying philosophical and scientific taxonomies. But so long
as we adhere to Aristotle's account of the problems of "science," inadequate
because of what he could not see, we will not be able to give adequate logical
expression (whether in terms of predicabies or problems) to what we, in contrast,
do see.
In explaining the full significance of this point, I shall talk in Porphyrian, rather
than Aristotelian, terms, because, as I have pointed out, traditional logic is
Porphyrian. I make the point, therefore, in terms of the omission of race from the
list of predicables. But it is precisely the same point which is being made,
whether we speak of problems or predicables; for, if there is no distinction between
species . and race, there will be only four problems and, in the Porphyrian transformation, only five predicables; but if species and race are distinguished, then there
must be eight problems (four about proper, and four about improper, species);
and, in the Porphyrian transformation, there will be ten predicables; or nine if
no distinction can be made between the difference constituting an accidental type
and its properties.. The reason for this will become apparent in the following
discussion. Here suffice it to repeat that my whole historical point can be made
either by saying that Aristotle should have considered two sets of problems,
focussed respectively on species and race, or by saying that Porphyry (and traditional logic) should have named race as one of the predicables and, in giving an
exhaustive enumeration of them, listed nine rather than five.

SOLUTION OF THE PROBLEM OF SPECIES

875

teristics: (I) being inferior, according to comprehension and extension, to the proper species, man, brute, plant, etc.; and (2) being
reductively in the category of substance. It cannot be said that
such terms as negro and Caucasian, oyster and elephant, mushroom
and rose, are not universal concepts, predicable of many. It cannot
be said that they are capable of being treated, as universals, under
any of the nine categories of accidents. Nor can they be predicated
as difference, or property, or accident, is predicated. H our analysis
of universals as predicable is to be complete, we must, therefore,
add a sixth logical concept to the five traditionally enumerated.
That sixth predicable is the logical intention of race.
Two consequences will be seen at once. In the first place, race
stands in a peculiar relation to species. For as species is an essential
unity, constituted by genus and difference, so race is an accidental
unity, constituted by species and accident. Hence if it be said that
there is no need to include race (because it is already potentially
present in species and accident) , the same thing can also be said
about species (which is potentially present in genus and difference) .
The predicables should, therefore, be either six or four, but not five.
Furthermore, if the logician is obligated to distinguish between
proper and improper species, there is a great advantage in recognizing that improper species are not species at all, but a radically
different kind of term, namely, race. 129
129 I cannot,
in brief compass, give a full account of the significance of race
as a predicable. But I should like to call attention to the following points. (1)
If the improper use of the word " species " by logicians is recognized, it is not
sufficient to dismiss this improper usage as mere ambiguity; something is being
signified, and the signification of the word " species," improperly used, must be
analyzed. Obviously what is being signified is a whole group of universals,
reductively in the category of substance.
(2) That race is a logical concept, a
pure second intention, can be seen in the false syllogism: " Jumbo is an elephant,
elephant is a race (of brnte), hence Jumbo is a race." As in the case of similar
false syllogisms, involving species and genus, the truth in the conclusion must be
expressed as follows: "Jumbo has a racial nature."
(8) Whereas genus and dif
ference, in the case of proper species, are both terms in the predicament of sub
stance, the " genus " in the definition of a race is predicamentally a
and the "difference" is predicamentally an accident. (4) In the definition of a
race, the " genus " is a proper species only in the case of races on the highest
level of generality in the eYtensive hierarchy, those formed by the addition of
the first accidental differentiae to essence; in the case of races on all subordinate
levels, the " genus " is simply a more general race; but since every race is reductively in the category of substance only by virtue of the specific essence to which
accidents have been conjoined, every race can be defined by stating a proper
species as the " genus " and then enumerating the differentiating accidents in the
order of their generality. (5) It is necessary to give a metaphysical account of
racial natures, just as we give a metaphysical account of specific natures, in the
light of which we can see that modes of predication follow modes of being. I

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J. ADLER

And in the second place, just as species signifies the object of a
real or essential definition, so race signifies the object of a nominal
or accidental definition. But, in either case, definition must be by
" genus " and " difference." Hence we come to see that the concept
race, because it signifies the object of accidental definition, requires
us to employ each of the five familiar predicables in an accidental
mode of signification. There must be racial genera and racial differences, as there are the genera of species and specific differences.
We have already seen this to be so, in our analysis of the kind of
genus which is determinable by two or more positive differences,
and the kind of positive difference which is contrary to another
positive difference, because each is rooted in a contrary (accidental)
perfection. Furthermore, there must be racial properties and racial
accidents. 129 " That this is so it will be discovered by anyone who
studies scientific taxonomies. Finally, there is the racial species
itself, which signifies the object of an accidental definition.
To give an adequate account of the predicables, therefore, one
must enumerate them in two distinct series: first, the set of terms
which have proper species as their center, including genus and
difference as constituting essential definition, and property and
accident, as following necessarily and contingently from the essence
defined; second, the set of terms which have race (or improper
species) as their center, including the type of genus and difference
which constitute an accidental definition, and the type of property
and accident which follow, in distinct ways, from the racial character as defined. Since the difference constituting a racial type is,
predicamentally, an accident, there is probably no way to distinguish a racial difference from racial properties. If we make this
second enumeration by speaking of racial genera (or generic races),
racial differences, or properties, racial species (or specific races),
and racial accidents, it will be seen that we have two sets of predicables, the second set as a whole being generated by the logical concept race, itself derived from the original five predicables by the
composition of species and accident. These two sets of predicables
formulate, respectively, the principles of the two distinct hierhave suggested some of the elements of such an account in The Problem of Species
(vd. 72-75, 81-82, 188-198, 246-276; THE THoMIST, I, 258-61, 267-68; II, 129-139,
266-86), but much more work remains to be done on this, and I shall return to
it in a later work on the problem of generation.
129 ' For some suggestions
concerning metaphysical grounds for the distinction
between racial properties and racial accidents (i. e., between the necessary and
contingent accidents of improper species or accidental types), vd. my discussion of
inseparable and separable accidents in The Problem of Species, pp. 192-195, 254 ff.;
THE THOMIST, II, 130 ff., 274 ff.

SOLUTION

OF THE PROBLEM OF SPECIES

377

archies-the essential and the accidental. They provide, furthermore,
the logical matrices for two distinct methods of knowing the natures
of things-the philosophical and the scientific. And, finally, they
show us how the two hierarchies can be ordered to one another, as
well as distinguished, by reason of the fact that the second set of
predicables, as a whole, is an expansion of the logical concept race,
derived from the first set of predicables by the combination of
essence (species) and accident. In these terms, too, the philosophy
and the science of nature can be well-ordered, as well as distinguished, and there need be no conflict or disharmony between
their diverse taxonomies. 180
In the light of the foregoing, I conclude that no logical theory of
species is adequate unless it employs the concept race as a basic
category in the manner suggested. Without this concept, and its
derivatives, confusion and disorder must result, for the traditional
five predicables cannot account for all the predications which
occur in our knowledge of nature. Thus, we see the profound inadequacy in Aristotle's logic, in that the account of the predicables
which it generates and its account of definition, could not be applied
to both the De Anima and the De Partibus Animalium without
confusion and equivocation; and at the same time we see the direct
cause of this inadequacy to be a failure to recognize that, in the one
case, proper species are being classified, and in the other, merely
1.ao I have pointed out the respects in which the intensive, or essential, hierarchy
is finite. In contrast, the extensive, or accidental, hierarchy is potentially infinite,
i. e., in the horizontal axis of Diagram 2, as we pass from terms of maximum to
terms of minimum generality. There is, of course, a fixed upper limit, for the
supreme accidental classes are proximate to the proper species which constitute
the essential hierarchy; but there is no fixed lower limit, for there is no principle
which stops us from making further accidental determinations. And, furthermore,
there is no principle which tells us how many levels of generality we shall employ
in constructing the extensive hierarchy. This indicates the contingency which is
intrinsic to scientific classification because it i.Y accidental; this explains why
scholastics have come to call the " species " distinguished by science, "systematic,"
i. e., not " natural." But, in another sense, of course, the scientific classifications
are natural, for there are, in fact, racial natures which can be classified. And
the scientist has good reason for regarding some of his classes as more natural than
others, namely, the kinds he calls " species " as opposed to the kinds he calls
" varieties " or " genera," " phyla," etc. A reformed Aristotelian logic, concerned
with the analysis of scientific as well as philosophical judgments, has an obligation
to formulate the rationale of scientific classification, considering especially the
factors of contingency and necessity which make some of the scientific distinctions
more natural than others. All of this would be done in a thorough development
of race as a predicable, for in treating its derivatives we would deal with what
scientists call "phyla," "genera," "species" and "varieties.'' Cf. The Problem
of Species: pp. 246-276; THE THOMIST, II, 266-96.

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MORTIMER

J. ADLER

races. The ultimate cause responsible for this failure was, of course,
the inchoate state of "scientia" as including both science and
philosophy without distinction.
20. I wish to repeat that the explanation I have just given of
the origin and persistence of a mistaken view about species (and
all that is related thereto in logic and the philosophy of nature)
is offered as an hypothesis for historical research, only on the
assumption that what I have claimed to be a demonstration is
genuinely so. This last remark calls for one word more. I am
aware of the fact that, within the boundaries of this one essay,
I both confess to having made a serious error in an earlier phase of
this work, and also claim now to be certain about having rectified
that error and about having demonstrated a solution of the problem
in consequence. I appreciate the doubts that this is likely to arouse
in a reader's mind. The reader may be justified in such doubts,
whether more or less than if I had not confessed to error, I cannot
say. But the reader's real concern must be, as mine is, with the
truth about the philosophical matters under consideration. His
aim must be, as mine has been, to try to answer the basic questions,
here raised, with certitude. The philosopher's task is to demonstrate. Even though errors occur in the process, he must not be
discouraged from continuing in the same way and toward the same
goal. For it is only by making his best efforts to demonstrate that
he will enable others to correct basic errors and to concur with
him in clearly achieved truth.
MoRTIMER

J. ADLER

University of Chicago,
Chicago, Illinois

ANALYTICAL OUTLINE OF ARTICLE
I.

INTRODUCTION

1. Relation of this work to The Problem of Species.
2. Relation of this work to "Problems for Thomists."
8. Preliminary statement of the basic error in The Problem of Species, which
falsified the issue.
4. How that error was corrected, and the consequences of its correction.
6. Outline of what is to follow.
U.

PRELIMINARY

CLARIFICATIONS

6. Verbal: the word " species " and the concept species; the distinction between
" ontology " and " logic."
7. Philosophical: the problem of universals-the community of specific natures vs.
the unity of concepts.

SOLUTION

m.

REFORMULATION

OF THE PROBLEM

OF SPECIES

879

OF THE ISSUE

8. Introductory outline.
9. Analytical account of the error in prior formulation of the first theory, and of
the false issue it generated.
10. Elimination of the error: the first theory rectified.
ll. Summary of the true issue: between the second theory and the first theory
as rectified.
IV.

THE ISSUE RESOLVED

1!!. Disproof of the second theory.
IS. Proof of the first theory (as rectified) .
V. CONSEQUENCES

OF TIDS RESOLUTION

H. Final formulation of two types of hierarchy, basic to the distinction between
natural science and natural philosophy in object and method.
15. Two minor points: (a) analogical predication of genera and species; (b)
metaphysical account of genus and difference in terms of common matter and
substantial form, with an analysis of the distinction between natural and
logical genus.
VI.

CONCLUSION:

AN IDSTORICAL

HYPOTHESIS

16. Definition of the mistaken view of species as it occurs in the tradition of
philosophia perennis, with an explanation of why the error is excusable.
17. First step in the hypothesis: origin of the mistaken view.
18. Second step in the hypothesis: persistence and spread of the mistaken view.
19. Completion of the hypothesis by a positive suggestion of how the error might
have been avoided.
20. Apologia.

BOOK REVIEWS
A Companion to the Summa, Volume ITI-The Fullness of Life. By
WALTER FARRELL, O.P. New York: Sheed & Ward, 1940. Pp. viii+
530, with index. $3.50.
This is the third of four volumes, the second to appear, in which the
author attempts to restate the thought of St .. Thomas' Summa for the
modern layman. The critical questions are three: first, what kind of transformation has Father Farrell made; second, for whom did he make it; and
third, is the transformation effective for that audience.
Father Farrell says in the Foreword: "This whole work is not a book
about the Summa, but the Summa itself reduced to popular language."
" Reduced to popular language," might mean a translation of the whole
Summa, or of certain parts, into modern English. But A Companion to the
Summa is neither of these, for there are many additions as well as subtractions. These, together with the manner of expression, would seem to
indicate that Father Farrell's transformation of the Summa is rhetorical.
The specifica.tion of the paraphrase, then, lies in the additions, subtractions
and the style.
It is a paraphrase of the entire Summa, insomuch as all the important
conclusions from the body of the articles are asserted. However they are
rhetorically argued, not demonstrated, and sometimes they are only
asserted. The Summa, then, is reduced scientifically and dialectically in
accordance with the rhetorical intention. Like the modern mathematician,
Father Farrell takes the Euclidian figures of St. Thomas and stretches them
into shapes recognizable to the modern man. And as in Topology, the
formal relations in a certain sense are preserved. The entire architectural
structure of the Summa is vaguely present, and the questions and articles
of St. Thomas merge into each other receding to the intelligibility of a confused whole. Thus the objections and answers of St. Thomas are often
omitted, and new and fewer objections are answered in a variety of ways.
But the foundation for the answer is often only a striking example,· and the
objections are quickly dismissed, e. g., "Some men have described faith
as an exaggerated optimism, a kind of super-confidence; but that was
because they did not know the purpose of faith. Others have reduced faith
to emotion; and that was because they did not know what faith was. Still
others have cynically put under faith every bit of our rational knowledge
of God; and that was because they did not know what man was " (page
4} . Frequently the objections are not stated explicitly, but are worked
into the answers, so that, almost before the reader knows it, whatever
truth there may have been in the objection has been reverted to the doctrine, e. g., " The fact that charity is not from nature, nor doled out in pro-

880

BOOK REVIEWS

381

portion to natural capacity for love, does not mean that there is nothing
for us to do about it. A man cannot sit back and wait for something to
happen, half-expecting, perhaps, that some morning he will wake up and,
to the astonishment of his wife, suddenly be a saint"· (page 71). But
again an objection is clearly stated with the distinctions necessary to
resolve it, e. g., " The point here is that such a discovery of a morality distinct froin religion is quite possible. Religion is not the product of authority nor the radical explanation of morality, at least not on the natural
plane. It flows from man's nature and is itself a command of natural law,
not the foundation of natural law. A community with morality, a moral
code, but devoid of religion, would be a community where the natural law
was operating but not perfectly, where one of the commands of natural law
had dropped out of sight" (page 251). Thus it would seem that whereas
St. Thomas' treatment of objections was determined by scientific necessity,
Father Farrell's method is determined by his intention of effectively
communicating the doctrine as a whole.
The vitality of The Fullness of Life is different from the vitality of the
Summa. The present work is very dramatic, stirring, hair-raising, humorous, consoling, where the Sttmma is sober and preeminently ordered. The
Summa quietly embraces a great multiplicity in the unity of its order.
The Companion to the Summa cannot stop in its momentum to consider
the multitude of distinctions. But, different as they are in their modes of
persuasion, the truths of which they persuade are the same. Tntimately,
too, ·their authorities are the same .. St. Thomas' arguments are founded on
Scripture, Church Councils, writings of the Saints and of Philosophers as
well as the certitude of human reason. Father Farrell's authority is the
same virtually, but it is communicated in the rhetoric, seldom explicitly.
Where St. Thomas says, " According to the words of St. Paul, ' The eye
hath not seen . . . what things God has prepared for those who love
him,' " Father Farrell says, " The fullness of faith, comparable only to the
limitless fullness of infinity, makes our natum.I life seem a narrow, dark,
blind corridor." Where St. Thomas says simply, "This follows necessarily
from this which is itself necessary," Father Farrell says," You must believe
this, because, if you do not, you will be miserable."
Father Farrell has added long discourses contrasting the man who is
seeking his proper end and through the proper means, and the man who has
lost his way, who is not seeking the proper end, or who is not using the
right means to achieve it. Almost every chapter ends with the same general peroration. For there are many deviations from the proper end, since
the means are many, and any of the means may be substituted falsely for
. the end. There are many ways of being lost, and in each chapter a different deviation is disclosed. The argument is something like this: man is
only happy in seeking his proper end, God; therefore by disregarding this

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BOOK REVIEWS

end to seek substitutions which can never satisfy his soul, he makes himself miserable. Inasmuch as theology is not only theoretical, the Summa
Tkeologica is practically affective, that is, affective because man by his
nature is moved to seek what he knows to be true and good. It is affective
therefore only because the will and the passions are moved by understanding, whereas the present book is affective, besides, by the very mode of its
expression.
Father Farrell is talking to men who are unfamiliar with the language of
the scholastics. Hence he must speak to them in their language, use their
vocabulary and idioms, and choose examples with which they are familiar
to illustrate points with which they are unfamiliar. The examples and
metaphors are important because they mediate between the experience of
the layman and the thought of St. Thomas. To mediate they must be
familiar to the layman and they must exemplify accurately the particular
truth. Thus we find an abundance of metaphors, many of which are exceptionally good, and some of which are inept. Inevitably the precision of the
thought of. St. Thomas must be lost in a popular restatement; but it is
unfortunate when, in addition, the precision proper to the rhetorical mode
is also lost through confusing examples, e. g., "Faith is like a jack-in-thebox: the spring is the intellect; the lid, holding down the spring, is the will.
The intellect is straining against the obscurity of faith. With the weakening of the will, through moral degeneration, the power to hold down the
intellect becomes less and less ·until finally, with sufficient weakening of
the will, the spring pops out-faith is lost" (page 11). Although this
example exemplifies something profoundly true, it would only communicate
to some one who is more schooled in theology than the layman for whom
the book is intended. In the example, the will of which Father Farrell
speaks is the will under the influence of the Holy Ghost, not the natural
will simply. The intellect, on the contrary is the natural intellect rebelling
against darkness. But without these distinctions it might seem as though
the will and intellect were opposed principles in human nature, or that
faith is retained through an opposition of natural principles, or even that
the will is superior to the intellect. Occasionally the terms of a metaphor
are not in the right order, e. g., "A child must be poured into warm
clothes: charity must be poured into us" (page 71). Stated as a proportion this reads, child is to clothes as charity is to us, hence the term!}
charity and child are representing the same thing, and clothes and us.
Another example of confusion in metaphor is, " Pictures, like persons,
remain strangers if we see them in the sad, false light of solitude. Compared with the full, human richness it displays when flanked, say, by the
mystery of a da Vinci and the delicate beauty of a Fra Angelico, a Titian
in solitary grandeur is reserved, even sullen and pouting. We cannot
always gather such a company on the same wall; but we have a mental

BOOK REVIEWS

383

gallery that can be arranged and rearranged at our pleasure. It would be
impossible, for instance, to hang side by side, in the same exhibit, the
astounding picture of an angry Christ violently driving the moneychangers from the temple and the pitiful picture of a modern racketeer
mercilessly beating a small storekeeper for not paying ' for protection.' But
arranged in such significant contrast in our mental gallery, they tell a story
that could be told as graphically by no other means " (page 193) . In this
instance Father Farrell tries to make clear the order of mental images
through the analogy of pictures in a gallery. Thus he says that the picture
of Christ and the picture of the racketeer would not be appropriately hung
side by side, but they are appropriately held together by the mind, that is,
as images for justice and injustice. But the point he is making depends on
the opposition between the order in the mind and the order in the arrangement of pictures. This is not to say that the thought is confused in these
examples. What he intended to say here, was that, just as pictures can be
arranged to illuminate each other in a gallery, so images can ,be arranged
to illuminate each other in the mind; but pictures can be arranged incongruously. Yet from the metaphor it would seem that if the pictures are
appropriately held together in the mind, they would be appropriately hung
together in a gallery, too. An analogy cannot be applicable in every
respect, but the similitude intended should stand out above the disparities.
On the other hand there are many delightful and accurate examples and
metaphors. They are even exciting in their perfect mediation, when a very
commonplace example throws light on a difficult point, e. g., "We are not
only irritated at faith's darkness, we too often resent the very authority
upon which faith rests. Behind this irritation there is a fear of error if a
truth is not subjected to the judgment of our mind that is not unlike the
uneasiness of a woman who is quite sure the house will not be cleaned
properly unless she cleans it herself" (page 6); or, "The coins of religion
which we jingle in our pocket as we go to pay our debt to GJ>d, have two
sides; on the one is the protestation of reverence for the excellence of God,
on the other the subjection of the creature who is man. We cannot split
the coin to hand over the reverence and retain the subjection; if we try it
we mutilate the coin, not only making it worthless but subjecting ourselves
to punishment. We cannot have one side of a coin without the other; they
are two sides of the same thing. More concretely, we cannot worship God
without subjecting ourselves" (page 254).
Proper to this rhetorical mode there is a personal quality, no trace of
which is to be found in the Summa Theologica. Father Farrell is speaking
to a specific audience, whereas St. Thomas is speaking to the disciplined
student of any time and place. There is a friendliness in Father Farrell's
book which is a wonderful and necessary encouragement to those readers
who would recognize their error. He makes a clear diagnosis of their error,

384

BOOK REVIEWS

and at the same time he communicates an awareness of their dignity as
human beings.
For whom, then, is this book intended? Not for beginners, simply,
because St. Thomas himself wrote for them. In the prologue to the Su,mma
he said, " Following the example of St. Paul who gave 'milk, not meat ' to
' little ones,' the Catholic teacher should so adapt his instructions that
they will be useful to those who are just beginning the study of sacred
science, as well as to those who already have a knowledge of divine wisdom. So, in this work I will try to write of Christian truths in such a way
that my words will be instructive to beginners." St. Thomas' work is
still read by beginners, but the beginner St. Thomas was thinking of, and
who still exists today, is disposed by right education to the truths of faith
and the authority of reason. But in addition to these, as a result of " universal education " in modern times, there is a large number of Catholics
(in the invisible as well as the visible Church) who are not so disposed.
Not realizing the inadequacy of their education they consider themselves
morally and intellectually competent. In fact they have neither the rectitude of the peasant, nor the discipline of the student. This " universal
education " has used reason to deny itself in the name of freedom, so that,
ironically, the denial of what is beyond reason has led to the denial of
reason itself. Thus the modern Catholic for the most part is divided, for
his thought is opposed to his faith. And it is for these that Father Farrell
seems to be writing. Particularly when they deny reason, men need the
Saint of reason. But since the reason he stands for is being denied, he must
be transformed into a rhetorician to attack modern sophistries. If Father
Farrell's work fails to lead his reader to St. Thomas, it will be through its
rhetorical weaknesses. Undoubtedly many readers will be brought through
it to St. Thomas himself. But possibly some will be untouched because of
its too insistent familiarity. Perhaps the incongruity of the appearance
and the doctrine is justified by the needs of the modern reader; but it is
possible that Father Farrell has forgotten how sensitive modern man is
to appearance.
But what is more important· Father Farrell is responsive to the needs
of his generation. However disparate his method to the method of St.
Thomas, he reveals himself a preacher of the Order of St. Dominic, whose
ultimate intention is not to make philsophers, but to lead men through
reason to sanctity. "The learned outside the true fold can be approached
through disputation which shows the excellence of our teachings as compared to their own. To win the less learned, however, use should be made
of metaphors, examples and stories, even as did Christ Himself, Who
' spoke to the crowds in parables, and without parables did not speak to
them' (Matt., xiii, 34) " (John of St. Thomas, Cursus Theologicus, I,
q. 1, a. 1).
CHARLENE SCHWARTZ,

T. 0. P.

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BOOK REVIEWS

fhe Philosophy of Physical Science. By Sm ARTHUR EDDINGTON. New
York: The Macmillan Co., 1939. Pp. ix
230, with index. $2.50.

+

Sir Arthur has repeatedly made statements on problems similar to those
he discusses in this book. Like many other physicists he evidently feels an
intense desire for a clarification of the principles on which modem science
rests and also for a justification of science as the only reliable approach to
reality. He, therefore, attempts a thorough analysis of principles and
methods, not hesitating to discuss even such subjects as existence and
epistemology. Hence the work is of wider scope than the title indicates.
Though not a fully rounded treatise. on natural philosophy, Sir Arthur's
book tries, at least, to lay the foundations of such a philosophy. In its
intention it is truly philosophical, although it is far from philosophical in
the way this intention is carried out.
The/ philosopher does not presume to pass judgment on physics; he does
not even presume to understand the physicist's statements unless he has
acquired some knowledge of facts and of methods. It is different with the
physicist's attitude in regard to philosophy. A scientist may be somewhat
suspicious of commonsense when he considers the ideas of the average
mind on physics; he trusts commonsense without reserve when he approaches philosophy. That is, he trusts his own commonsense and the
notions he has of philosophy and its methods. Of the latter he evidently
has no clear idea; that there might be a method in philosophy, as definite
as his own in science, is a thought the scientist does not consider at all.
Sir Arthur's book is just what one would expect from a man who is a
specialist and, probably, an authority in his own field, but to whom philosophy is an unexplored country. The philosophy propounded in this book
reminds one of those maps the first explorers made of the interior of
Africa-out of proportion, fantastical, empty places filled in with the
creatures of the explorer's imagination.
The general philosophical bases on which this work rests may be
described as a naive Kantianism strongly colored by psychologistic prejudices. What in Kant is the achievement of Bewusstsein ilberhaupt becomes
with Sir Arthur a characteristic of individual mental states. Referring to a
quotation taken from C. E. M. Joad, the author remarks (p. 214) that
" the conception of a sensum distinct from the sensing appears to have a
purely linguistic origin; but the important conclusion that the sensum is
something external to consciousness is based on the existence of a number
of different ways in which it can be related to consciousness." This statement is enlightening. Apart from the influence of logico-positivistic notions noticeable in Sir Arthur's world of ideas, there is the curious notion
of a sensum, not distinct from the sensing whereby it is apprehended, and
yet " related to consciousness " in manifold ways. The denial of any difference existing between the sensation as mental state· and the sensum

14

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BOOK REVIEWS

as transcendent object apprehended by means of sensation is, of course,
based on an insufficient analysis of the facts of cognition. That the author
has, in this regard, remained an adherent of philosophies which, though
not quite abandoned, have become more than doubtful in recent times, is
shown also by his remark on hallucinations. In fact he but repeats what
was the common opinion some time ago; but what would Sir Arthur say
if someone were to make assertions on physics no longer in accordance
with the ideas of the physicists? If the philosopher is warned, and justly
so, not to talk on science without having first acquired the necessary
knowledge, let the scientist follow the same rule when he is going to talk
on either philosophy or psychology.
Ever since the famous English scientist began to philosophize, it has
been pointed out to him that his assertions are not as evident as he thinks
them to be and that the principles on which he bases his conclusions are
very questionable. These criticisms have not, it seems, induced the author
to revise any of his ideas; his viewpoint is the same as the one he held
several years ago in his book The Nature of the Physical World. We are
told anew that it is not " things " we are aware of but " structure." " To
be quite precise, it is structure of the kind defined and investigated in the
mathematical theory of groups" (p. 147). It is not easy to see how this
assertion fits in with the other on sensation: "The starting point of physical
science is a knowledge of the group-structure of a set of sensations in a
consciousness." The many "fragments of structure" arising in individual
minds are collated, the gaps are filled in by an inferred structure, and we
thus obtain the structure known as the physical universe. But we, that
is, the individual minds, become aware of these fragments only by means
of new sensations, resulting from the printed or spoken words of others.
There seems to be no way out of this subjectivity; any " collation" is as
subjective and belongs as much to an individual consciousness as original
sensations. How there can be any " objective " knowledge of mere structures remains a puzzle which Sir Arthur's philosophy is not capable of
solving.
The author's trust in the " structure" as the only object of knowledge,
at least as far as science is concerned, is absolute. " I believe there are
[here there is a series of eighty digits] protons in the universe and the same
number of electrons" (p. 170). Why?-because the " theoretical calculation of the cosmical number N depends on the fact that a measurement
involves four entities and is therefore associated with a quadruple existence
symbol. . . . The cosmical number must be the total number of independent quadruple wave functions, which is found to be x 136 x
"
(p. 76) . There cannot be more or less elementary particles, or whatever
one may call them, because the kind of structure chosen by the scientist
or opposed by " sensations " does not allow for more. " Reason finds certain laws in nature, because they were put there first by reason," wrote

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Kant. " Reason " in this statement is used in two senses; it signifies individual reason in the first, and Bewusstsein uberhaupt in the second part.
It is not easy to know what Kant really wanted to refer to when he spoke
of the Bewusstsein iiberhaupt, but it is more than probable that he did
not refer to individual and phenomenal consciousness. 1 These two senses
are joined into one in Sir Arthur's philosophy, which thus becomes a
psychologistic Kantianism-far from what the philosopher intended his
system to be.
It is hardly necessary to enter into details. A philosophy resting on such
questionable presuppositions is questionable in itself. To the author's
assertion there applies a remark by E. Husserl, that it is not always science
which speaks when the scientist speaks, and never less than when he
speaks on" natural philosophy." 2 The philosopher is willing to learn from
the .scientist what the methods, the facts, the theories of science are. He is
not willing to listen to the scientist when the latter speaks of philosophy
without taking pains to make himself acquainted with philosophical principles and methods. The scientist is fully justified in criticizing the philosopher if the latter makes assertions about facts and theories of science on
the basis of purely philosophical principles, but it is not science which can
tell us whether we deal with sensations and structures, or with objective
facts of which we are made aware by sensations and to which our theories
refer. Philosophica philosophice traduntur et ... judicantur. All our
respect for the scientist Eddington and his achievements cannot hinder us
from rejecting his philosophy as dilettante and utterly insufficient.
RunoLF ALLERS

Catholic University of America,
Washington, D. C.

Physics and Reality. Lectures of Aristotle on Modern Physics at an International Congress of Science, Cambridge, 679 Olymp., 1940 A. D. By
KuRT RIEZLER. New Haven: Yale University Press, 1940. Pp.
The author is on the staff of the New School of Social Research, New
York. He publishes this book as "a humble experiment in thought dedicated to those, who conscious of a widening cleavage between nature and
man, are willing to inquire into its causes." To this end he imagines Aristotle returning from the land of shadows and delivering ten lectures to
modern scientists. Four of these lectures form the first part, entitled " The
Impasse"; the title of the second part is "The Other Way." The lecturer
after having "invoked the gods according to my country's custom," dis1
2

Cf. E. Herrigel, Die metaphysische FMm, Tiibingen: 1929.
ldeen zur reinen Phiinomeriologie, Halle a. S.: 1913, p. 38.

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cusses motion, classical and quantum physics, and event; this critical analysis is followed by studies on concreteness, substance, motion, time, the one
and the many, nature and man.
It is not the admirable achievements of science which make " Aristotle "
wonder; what amazes him is that the most intense experience man has, his
own desire for knowledge, is not a subject of investigation. The further
man penetrates into the laws of nature the further he gets away from it,
the more elusive it becomes; man is separated from nature .. " What, by
Zeus, have you been doing?" says" Aristotle." Notwithstanding the degradation of nature implied in the faith of the theologians, theology embraced
man and nature as one mystery, but this unity is rent for the scientist.
He cannot help being human, therefore he squints toward theology
amidst his numbers, and he feels guilty because he cannot help squinting.
These remarks, taken from the first six pages, characterize the general
attitude of the lecturer.
He
to analyze motion which he understands as comprising all
kinds of change. It is necessary to distinguish between the one problem
implied in the assertion, "motion is," and the other referred to in the
question, "what is motion." The scientist as such is not concerned with
the meaning of " is "; he is intent only on discovering and formulating the
order of all possible observations, and he limits his observation to the
measurable, leaving out all non-measurable parts of his perceptions. Individual differences are eliminated; all observations refer to an anonymous
subject, " a robot whose being consists in reading numbers from the pointers
of your instruments." The scientist's "objective" reality is merely an
intersubjective order relative to the robot observer. To this notion also
refers the " is "; motion is within this order and defined by it. Classical
physics, i. e., the physics prior to the quantum theory faces the problem
of two unexplainable contingencies, the definite world-geometry and the
initial constellation. Becoming is unexplainable, and unstatable as well.
No reference to four dimensional space-time is of any help; "the world
extended in time stands still." It is only because the physicist involuntarily
relates his pre-scientific experience of motion to his four dimensional system of symbols that the semblance of rest to movement is brought about.
The notion that· time points in a certain direction is not deducible from
the second principle of thermodynamics; it originates in immediate personal experience. Another serious difficulty arises in regard to the notion
of substance. There is no "one"; there is only the whole cosmos and every
determination of any " one," as a part within this whole, results from some
separation made by the mind. Thus, "ones" exist not by nature--.pvu€tbut by an act of the mind-9lu£t· The identity of the individual self becomes a perfect riddle. There is no legitimation for this theory in the
space-time continuum. In a physics which is based on the notion of

BOOK REVIEWS

389

"field " and defines matter by "field," motion does not move; when there
is no motion, neither is there any rest.
The difficulties caused by quantum physics are, in the truth, the difficulties inherent in the fundamental concepts of classical physics. Quantum
physics is faced by three difficulties: the relation between the observed
process and the process of observing; the fact that all statements of microphysics are bound to the concepts of classical physics; the problematic
nature of probability. The statements of this physics do not refer to any
self-identical, individual subject; they refer to aggregates or classes. The
data on which microphysics bases its statements are supplied by pointer
readings; they imply notions like velocity, interval, potential. Microphysics
is {as are its laws), secondary to the microphysical events, but the latter
have to be stated in terms of this secondary knowledge. The development
of physics from Galileo to Einstein is a gradual change of the frame of
reference so as to make possible the incorporation of new facts. There is
no possibility of a similar adaptation in microphysics, because the instruments obey the microphysical laws. The laws of microphysics refer to
numerical probabilities, the distribution of which define a class, and the
most that can be asserted of an individual case is that it belongs to some
class thus defined. The statement that the psi function " makes a jump "
is unjustified and unjustifiable, because in truth there is no real subject
which could jump; the subject spoken of is only a grammatical one. All
statements about elements are only probable; certainty is had only in regard to aggregates. What is probable? What does the vibrating of a
probability wave mean? The answer is: the probability of an event-a very
problematic notion. Also, there is the mystery of definite numbers, as the
elementary quantum, or Planck's constant. They are inexplicable, mysteries. Event, in classical physics, is defined by motion. This is impossible
in quantum physics; here, event has to define motion, but it certainly cannot be defined in terms of " jump."
Causaljty has been eliminated, quite logically, from classical physics.
A cross section of three dimensions and infinitely small in the fourth
dimension of time contains certain values, called parameters. They obey
definite differential equations-the laws of physics. This is the assertion
regarding physical causality; so far as physics is concerned this is a correct
definition. No other causality can exist. Indeterminism, often spoken of
by certain physicists, is not another system to be opposed to causality.
Indeterminism is a pure negation, making no positive statement at all; it
cannot, by itself, pass from negation to any positive assertion.
Aristotle's mistake was to interpret the movement of. the celestial bodies
by conceptions developed from living experience. The scientist of to-day
inverts this mistake and attempts to interpret life and himself by the frag-

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BOOK REVIEWS

mentary knowledge of inorganic nature. Both mistakes can be avoided by
devising a scheme of nature embracing reality as a whole. One has to
revise the meaning of " is." Whether this attempt be christened physics,
or metaphysics, or ontology does not matter; it has to be made.
" Aristotle " proceeds in the second part to talk about their being to the
scientists, not as they are scientists but as they are human beings-indeed,
as he says, an unaccustomed way of talking to scientists. There is a twofold
meaning of "is" and, correspondingly, there are two meanings of nature.
The physicist understands nature as world, the order of the many in
space and time. Aristotle conceives nature as " Physis," the structure of
concreteness so far as the concrete is concrete; nature as Being; " Physis
born together," as Plato said.
(Here, " Aristotle " without explicitly referring to it, reveals one of the
roots of modern philosophy of existence, which, at least with Martin
Heidegger, started with a shifting from Kantianism and Phenomenalism to
Aristotelean ontology. It would make an interesting study to clarify the
correlations obtaining between developments in modern physics and certain
modern philosophies which apparently are of a quite different spirit and,
nevertheless, express the same basic mentality. The lecturer, however, is
not concerned with modern philosophy.)
In physics the world vanishes; it is replaced by abstraction. Being without a world is nothing, a world not revealing being is vain. " Aristotle "
wants to find t"he way back into the" inward density of being." The road
is the one of ontology. He tries, accordingly, to make his audience see the
true significance and the implications of substance. This notion has disappeared from physics which rather deals with relations of relations only,
and which, to reach an " objective " world has discarded also the relation to
the observer, "retaining a 7rpoc; -rl without a ,.[, a kind of being-to-others
without others." The being of the observer himself, his "inner density of
concreteness" is neglected. Any concreteness, accordingly, disappears; no
substance is conceivable any longer. " Objective being is the being of subjects as substances, r':>t of objects. that are not related to subjects." Motion
too is incomprehensible without substance and without potentiality and
actuality being taken into consideration. Tendencies, impulses, vectors,
etc., are words to mask what Aristotle spoke of as potency.
Aristotle's intention, when studying motion, was to discover terms which
aJ:ply both to the reality behind physics and to human life. These terms
may be vague, lacking definiteness; but the terms of physics are clear and
distinct only as long as one remains within a mere number space. They
are accurate only in an empty world. The world of physics and the reality
wherein man lives are separated by an abyss.
"Aristotle's " ideas as developed in these lectures hinge on the conception
that reality has "both an outward breadth and an inward density." Only

BOQK REVIEWS

891

when taken together can they reveal reality. What physics talks of is not
the cosmos; it is a " message of the cosmos." As long as physics is considered as the true and the only approach to reality, reality will elude man's
attempts to get hold of it.
This is, of course, a fragmentary and very incomplete rendering of these
lectures. One wonders how far these ideas mirror truly what the Philosopher
would have thought had he known modern science. No doubt the criticisms
and the views he opposes to the modern conception are largely justified.
No doubt also the modern scientist will not know what to do with a notion
like " density of being "; you cannot measure it, therefore it has no meaning.
But this is just the point of " Aristotle "; there is more meaning in reality
than the statements of the physicist reveal, and this other meaning is even
more meaningful, as it were, than the formulae of physics, however well
demonstrated by experiment. " Aristotle " voices, as in fact all true philosophy must, the basic ideas of mankind, clarifying and purifying what
commonsense dimly apprehends. Whether or not one agrees with Dr.
Riezler in all points, there is nothing to lessen the value and importance
of his work. If nothing else, the book is exceedingly provocative. It ought
to be read carefully by anyone interested in philosophy of nature. If not
too prejudiced either by a blind belief in the omnipotence of science or by
an unrealized or only half-realized metaphysics, the scientist too may profit
by its study. The Schoolman will find many ideas he is accustomed to
cherish and to see ignored by tl!.e moderni. He will also discover some points
with which he cannot but disagree. There is a note on the analogia entia
as conceived by Aquinas which seems to imply some misinterpretation of
this idea. But, the note is so brief that this reviewer is not quite sure that
he understood the author's meaning. Whatever one may find objectionable
in this work as a whole, it is interesting, provocative and definitely worth
reading. If it receives the attention it deserves, it may start some fruitful
discussion.
RUDOLF ALLERS

The Steps of Humility. By BERNARD, Abbot of Clairvaux. Translated,
with Introduction and Notes, as a study of his Epistemology by George
B. Burch. Cambridge, Mass.: Harvard University Press, 1940. Pp.
xi+
with index. $3.00.
From the viewpoint of the reviewer this work naturally falls into three
parts: the Latin text of Bernard's work, the translation, and the introduction
and notes. The text is that of Dom Mabillon; the translation is the author's
own. With neither can we have any quarrel; the translation is especially
praiseworthy for it captures the spirit of the Latin original in a remarkable
manner.

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BOOK REVIEWS

We cannot be as enthusiastic about the introduction and notes. The
introduction especially is an ambitious piece of research on Bernard's
spiritual doctrine. Practically all of the saint's works are quoted and there
is an obvious attempt to present his thought objectively. But here, and
especially in the notes, Mr. Burch betrays a lack of real appreciation for
Bernard's thought which he interprets in terms of modern philosophy, in
particular, Kantian philosophy.
Two examples will suffice. In the introduction (pp. 88-84), after exposing Bernard's thought on the various types of consideration, the author
concludes: " There are, then, including the subdivisions, six kinds of consideration. These are identical with the six ' ways of knowing ' of modem
philosophy: dispensative consideration is ' pragmatism '; estimative consideration of visible things is ' empiricism '; estimative consideration of
invisible things by opinion is ' scepticism '; that by faith is ' authoritarianism '; that by understanding is ' rationalism '; speculative consideration is
' mysticism.' "
The second example is more conclusive of the author's ignorance of
Bernard's doctrine, as well as of the Catholic doctrine of the Trinity, which
Bernard certainly held. In the notes (p. 250), the author says: "Ultimate reality, proximate reality, and appearance are absolutely one, because
they are identical, being the same thing considered from different points
of view. Yet they are absolutely three, because they are more different from
each other than any other things whatever, all other divisions or distinctions
being merely subdivisions within one of these, which are the most ·basic
categories possible. Ultimate reality is ultimate, itself derived from nothing,
all else derived from it. Proximate reality is derived from ultimate because
it is an appearance of it. Appearance is derived from proximate reality because it is an appearance of it, yet not in quite the same way as proximate
reality is derived from ultimate. Appearance is also appearance of, and so
derived from, ultimate reality. Their relations, therefore, are those of the
Christian Trinity." It would be amusing to quote more; but this is enough
to show that Mr. Burch has not written a book on the epistemology of St.
Bernard.
JAMES

Dominican House of Studies,
Washington, D. 0.

M. EGAN, O.P.

BRIEF NOTICES
Mediaeval Studies. Vol. II, 1940. The Pontifical Institute of Mediaeval
Studies. New York: Sheed & Ward. $5.00.
The second volume of Mediaeval Studies contains the following papers:
"The Teaching of the Canonists on Usury: IV. Punishment of Usurers,
by T. P. McLaughlin; "The. Treatise De Anima of Dominicus Gundissalinus," edited by J. T. Muckle, C. S. B.; "Ralph Niger-An Introduction to
his Life and Works,'' by G. B. Flahiff, C. S. B.; "Origin and Significance
of the Byzantine Iconoclastic Controversy,'' by G. B. Ladner; "The
Canzone d'Amore of Cavalcanti According to the Commentary of Dino
del Garbo,'' by Otto Bird; " The Franciscan Ordo Missae in the Thirteenth
Century," by V. L. Kennedy, C. S. B.; "Albertus Magnus on Aristotle's
Second Definition of the Soul,'' by William Gorman; " An English PilgrimDiary of the Year 990,'' by F. P. Magoun, Jr.; and "A Teachnical Construction in Old Engijsh,'' by L. K. Shook, C. S. B.

L'Hygi{me mentale et l'Education. Premiere Congres annual, 19-22 juin
1940. Ottawa: Les Editions du Levrier.
In the introductory paper Fr. ·Louis-Marie Regis, 0. P., explains the
significance of the meeting whose proceedings are included in this book.
He points out that for the art of education a speculative knowledge of the
child's nature, though ol extreme importance, is in fact insufficient. As an
art, education is dominated by the particular nature of the work to be
done; the children with whom the teacher works are individual specimens of
human nature and not merely imperfect adults; Such individualized knowledge can come only from the experimental sciences. Their data plus the
truths .of rational psychology are essential to the teacher.
The papers read at this first meeting were: " L'Enfant et la Criminologie,''
by Dr. Antonio Barbeau; "The Personality Development of the Secondary
School Child,'' by Dr. E. C. Webster; "Hygiene Mentale et Education
Sexuelle,'' Noel Mailloux, O.P.; "The Hygiene of Mental Work,'' by Dr.
A. G. Bills; "La Pratique de I 'Hygiene Mentale a l'Ecole,'' by Dr. A.
Marcotte; " The Role of the Teacher in Character Education,'' by Dr •.
J. A. Long.

898

394

BRIEF NOTICES

Reason. (University of California Publications in Philosophy, Vol. 21.)
Berkeley, Calif.: University of California Press, 1939. Pp. 228.
For several years the University of California has published annually
a volume of lectures given by scholars who discuss a certain topic from
their respective viewpoints. The lectures of 1938 deal with a very actual
topic--reason. Actual it is, because the right understanding and evaluation
of reason is a basic issue in the whole life of mankind and particularly in
a crisis. The lecturers, all from the staff of the University of California,
envision their common topic under the headings: " The Appeal to Reason,"
by W. R. Dennes; "Artifacts of Reason," by J. Loewenberg; "Reason in
Science," by V. F. Lenzen; "Definition," by St. C. Pepper; "Reason in
History," by E. W. Strong; "Rationality and Irrationality," by P. Marhenke; "Reason as Custodian,' by D. S. Mackay; "Reason and Purpose,''
by G. P. Adams. Many of the authors start or end with statements taken
from Hume or embodying Hume's conceptions. On the other hand, there
are statements which, although couched in a different terminology, remind
the reader of well-known concepts. Both Loewenberg and Lenzen, for example, operate with a notion very much like the one of the degrees of
abstraction. Mackay emphasizes the difference of "logical rigor " in
science and in philosophy, not because metaphysics is devoid of such rigor,
but because its " rigor " is of another kind from that of science. Adams
affirms that there is, with man, " a new dimension added to the old principles of organization," the name of this new dimension being " reflection."
The lectures of the present volume may appear unsatisfactory and disconcerting to those who incline more toward the Scholastic viewpoint, and
will be criticized by others for not being " scientific " enough and too unwilling to make far-reaching concessions to positivism. In any case, they
are stimulating, interesting, informative. And, most of all, they are a
testimony to the aliveness of philosophical passion in an age very much in
need of such an attitude and its achievements.

Scholasticism and Politics. By JACQUES MARlTAIN. New York: Macmillan,
1940. Pp. viii + 248. $2.50.
Readers will be interested in this late.!lt exposition of M. Maritain's
thought on political problems, originally presented as a series of lectures at
Chicago University. The fundamental theme. is the de.fense of man's
humanity against the inhumanity rampant in the world today. In the
first chapter the author summarizes his thought on integral humanism.
This is followed by discussions of the dignity of the human person, its
peculiar characteristics, and the failure of materialistic systems, inspired
by Freud, to preserve human dignity. There is a further defense of the
author's widely-known distinction between person and individual.

BRIEF NOTICES

895

Joannis Dominici Lucula Noctis. By EDMUND HUNT. (Publications in
Mediaeval Studies, IV: The University Qf Notre Dame.) Notre Dame,
Indiana, 1940. Pp. xxxi + 482.
Giovanni da Saminato, a monk in the Camaldolese Monastery of St.
Mary of the Angels wrote to Coluccio Salutati, the outstanding defender of
humanistic studies, a letter warning him of the folly of the classics. Salutati
replied; the monk, feeling incapable of answering, sent the reply to Joannes
Dominici at the Dominican Monastery of Santa Maria Novella. Dominici's
answer is the Lucula Noctis, here edited by Edmund Hunt. This edition is
based on the recently discovered manuscript in the University of Chicago
Library, which is the very one read by Salutati himself. The Lucula Noctis
is an interesting document in the history of Christian education. In the
first twelve chapters Dominici presents a very strong case for the humanists.
The remaining thirty-five chapters are a refutation of these arguments.

Theotogia Fundamentalis. By H. C. CoTTER, S. J. Weston, Mass.: 1940.
Pp. 789, with index. $3.50.
This work follows to a great extent the traditional lines of treatises on
Apologetics. The form is possibiy more rigidly scholastic than usual, but
the Latin is simple and readable. The section on Scripture is rather extended-intentionally,
says the author, since Scripture is the soul of
theology.

The Doctrine of the Trinity. By FELIX KLEIN. Translated by D. J.
Sullivan, M.A. New York: Kenedy, 1940. Pp. 298. $2.50.
By an excellent combination of positive and scholastic theology, Abbe
Klein presents as clear a picture of the mystery of the Trinity as one would
wish. The profundity of the mystery is not lost, but simplicity of language
puts the book within the grasp of all.

The Spiritual Life according to St. Isidore of Seville. By Sister PATRICK
JEROME MULLINS, 0. P. (The Catholic University of America Studies
in Medieval and Renaissance Latin Language and Literature, Vol.
XIIT.) Washington, D. C.: Catholic University Press, 1940. Pp.
xi + 212, with index. $2.00.
In tb.e first two chapters the author considers the life and character of
St. Isidore and the sources of his doctrine. The doctrine is then exposed
in three chapters, entitled: The Foundation of the Spiritual Life; The Way
of Perfection; The Ideal of Perfection. A select bibliography is appended.

BOOKS RECEIVED
Allie, Jean-Leon. L'Argument de Prescription dana le Droit Roman, en
Apologetique et en Tkeologie Dogmatique. Ottawa,1 Les Editions de
l'Universite d'Ottawa, 1940. Pp. 220, with index.
Bryan, W. L. Wars of Families of Minda. New Haven: Yale University
Press, 1940. Pp. xv + 148, with index. $2.00.
Efron, A. The Sacred Tree Script: The Esoteric Foundation of Plato'·a
Wisdom. New Haven: Tuttle, Morehouse and Taylor Co., 1941. Pp.
xxiv + 872.
Garlan, E. N. Legal Realism and Justice. New York: Columbia University
Press, 1941. Pp. xii + 161, with index. $2.00.
Healy, Sr. Emma Therese. Saint Bonaventure's "De Reductione Artium
ad Theologiam." St. Bonaventure, N. Y.: 1989. Pp. 212.
Kieda, Francis, C. R. De Matrimonii Celebratione Per Procuratorem.
Rome: Typis Ponti:ficiae Universitatis Gregorianae, .1989. Pp. xii +
104, with index. $1.25. (Procurable through author, Box. 4468, Brookland, D. C.)
Leen, James, C. S. Sp. By Jacob's Well: A Planned Retreat. Trans. by
Edward Leen, C. S. Sp. New York: Kenedy, 1940. Pp. 419. $8.50.
Mackey, J. H. A Preface to Christian Theology. New York: Macmillan,
1941. Pp. x + 187, with index. $2.00.
O'Connell, D. M. Kindly Light. (A Second Cardinal Newman Prayer
Book.) New York: America Press, 1941. Pp. 846, with indices. $2.50.
Rail, H. F. Christianity: An Inquiry into ita Nature and Truth. New
York: Scribner's, 1940. Pp. xvi + 868, with indices. $2.50.
Russell, Bertrand. An Inquiry into Meaning and Truth. New York:
Norton, 1940. Pp. 445, with index. $8.75.
Schroll, Sr. M. Alfred. Benedictine Monasticism as Reflected in the Warnefrid-Hildemar Commentaries on the Rule. New York: Columbia University Press, 1941. Pp. 217, with index. $2.75.
Science, Philosophy and Religion: A Symposium. New York: Conference
on Science, Philosophy and Religion, 1941. Pp. 448. $1.50.
Vann, Gerald, 0. P. Saint Thomas Aquintia. London: J. M. Dent & Sons,
1940. Pp. ix + 182. 6 s.

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