METAPHYSICS
BOOK IX
POTENTIALITY AND ACTUALITY
CONTENTS
LESSON I
The Division of Potency into Active and Passive. The Nature of Incapacity and Privation
ARISTOTLE’S TEXT Chapter 1: 1045b 27-1046a 35
742. We have dealt then with the primary kind of being and the one to which all the other categories of being are referred, namely, substance. For it is in reference to the concept of substance that the other categories are called beings, i.e., quantity, quality, and others which are spoken of in this way; for all involve the concept of substance, as we have stated in our first discussions (562). And since being is used in one sense of quiddity or quantity or quality, and in another sense of potency and actuality and activity, let us now establish the truth about potency and actuality. And first let us consider potency in the most proper sense of the term, although not the one most useful for our present purpose; for potency and actuality are found in more things than those which are referred merely to motion. But when we have spoken about this sense of potency we shall, in our discussions about actuality, also explain the other senses of potency.
743. That the terms potency and can are used in many senses we have made evident elsewhere (467). And all of those senses of potency which are equivocal may be dismissed; for some senses of potency [or power] are merely figurative, as in geometry. And we say that things are possible or impossible because they either are or are not in some particular way. But all those potencies belonging to the same species are principles and are referred to one primary kind of potency, which is the principle of change in some other thing inasmuch as it is other. For one kind is a potency for being acted upon, which is in the patient and is the principle of its being passively moved by another inasmuch as it is other; and another kind of potency is the state of insusceptibility to change for the worse and to corruption by some other thing inasmuch as it is other, i.e., by a principle of change. And the intelligible character of the primary kind of potency is found in all of these terms. Again, these potencies are said to be potencies either just for acting or for being acted upon, or for acting or being acted upon well, so that in these latter kinds of potencies the notes of the prior kind are somehow present.
744. It is evident, then, that in one sense the potency for acting and for being acted upon are one; for a thing is potential both because it itself has the potency for being acted upon, and because something else can be acted upon by it. And in another sense these potencies are different; for the one is in the patient, since it is because it has a principle, and because matter is a principle, that the patient is acted upon and changed by something else. For what is oily is capable of being burnt, and what is yielding in some way is capable of being broken (and the supposit is capable of being expressed);’ and the same is true in other cases. And another kind of potency is in the agent, as the potency to heat and the potency to build-the former in the thing capable of heating, and the latter in the person capable of building. Hence, inasmuch as a thing is by nature a unity, it cannot be acted upon by itself; for it is one thing and not also something else.
745. And incapacity or impossibility is the privation contrary to such potency, so that every potency and incapacity belong to the same subject and refer to the same attribute. And there are various kinds of privation; for there is one kind of privation when a thing does not have some attribute which it is naturally disposed to have, either in general, or when it is naturally disposed to have it. And this is so either in a particular way, for example, completely, or even in any way at all. And in some cases if things are naturally disposed to have some attribute and do not have it as a result of force, we say that they are deprived of it.
COMMENTARY
Different kinds of potency
1768. Having established the truth about being as divided into the ten categories, the Philosopher’s aim here is to establish the truth about being as divided into potency and actuality. This is divided into two parts. In the first he links up this discussion with the foregoing one, and explains what he intends to do in this book. In the second (1773) he carries out his announced plan.
He accordingly points out, first, that he has already discussed above the primary kind of being to which all the other categories of being are referred, namely, substance. And he explains that all the other categories are referred to substance as the primary kind of being, because all other beings— quantity, quality, and the like—involve the concept of substance. For being is said of quantity because it is the measure of substance; and of quality because it is a certain disposition of substance; and the same thing applies in the case of the other categories. This is evident from the fact that all accidents involve the concept of substance, since in the definition of any accident it is necessary to include its proper subject; for example, in the definition of snub it is necessary to include nose. This was made clear at the beginning of Book VII (1347).
1769. But being is variously divided. (1) One division is based on its designation as whatness (i.e., substance), quantity or quality, which is its division into the ten categories.
(2) Another is its division into potency and actuality or activity, from which the word actuality [or act] is derived, as is explained later on (1805). And for this reason it is now necessary to deal with potency and actuality.
1770. It is first necessary to speak of potency in its most proper sense, although not the one which is most useful for our present purpose. For potency and actuality are referred in most cases to things in motion, because motion is the actuality of a being in potency. But the principal aim of this branch of science is to consider potency and actuality, not insofar as they are found in mobile beings, but insofar as they accompany being in general. Hence potency and actuality are also found in immobile beings, for example, in intellectual ones.
1771. And when we shall have spoken about the potency found in mobile things, and about its corresponding actuality, we will also be able to explain potency and actuality insofar as they are found in the intelligible things classed as separate substances, which are treated later on (1867). This order is a fitting one, since sensible things, which are in motion, are more evident to us, and therefore by means of them we may attain a knowledge of the substances of immobile things.
1773. That the terms (743).
Then he deals with potency and actuality; and this is divided into three parts. In the first he discusses potency; and in the second (1823), actuality; and in the third (1844), the relationship of actuality to potency.
The first is divided into two parts. In the first of these he discusses potency itself. In the second (1787) he discusses potency in relation to the things in which it is found.
The first is divided into two parts. In the first he deals with potency; and in the second (1784), with incapacity.
In regard to the first he does two things. First, he explains the different senses of potency. Second (1781), he makes evident a truth about potency from the things previously laid down.
He accordingly says, first, that it has been shown elsewhere, i.e., in Book V of this work (954) that the words potency and can have a multiplicity of meanings. But in some cases this multiplicity is a multiplicity of equivocation, and in others it is a multiplicity of analogy.
For (1) some things are said to be capable or incapable because they have some principle (+) within themselves, and this refers to those senses in which all potencies are said to be such not equivocally but analogously. (2) But other things are not said to be capable or able because of some principle which they have (~) within themselves; and in their case the term potency is used equivocally.
1774. Therefore, with regard to those senses in which the term potency is used equivocally, he says that these must be dismissed for the present. For the term potency is referred to some things, not because of some principle which they have, but in a figurative sense, (1) as is done in geometry; for the square of a line is called its power (potentia), and a line is said to be capable of becoming its square. (2) And similarly in the case of numbers it can be said that the number three is capable of becoming the number nine, which is its square; because when the number three is multiplied by itself the number nine results, for three times three makes nine; and when a line, which is the root of a square, is multiplied by itself, a square results. And the same thing applies in the case of numbers. Hence the root of a square bears some likeness to the matter from which a thing is made; and for this reason the root is said to be capable of becoming its square as matter is capable of becoming a thing.
1775. And (3) similarly in the considerations of logic we say that some things are possible or impossible, not because of some potency, but because they either are or are not in some way; for those things are called possible whose opposites can be true, whereas those are called impossible whose opposites cannot be true. This difference depends on the relationship of predicate to subject, because sometimes the predicate is repugnant to the subject, as in the case of impossible things, and sometimes it is not, as in the case of possible things.
1776. Passing over these senses of potency, then, we must consider those potencies which are reduced to one species, because each of these is a principle. And all potencies spoken of in this sense are reduced to some principle from which all the others derive their meaning; and this is an active principle, which is the source of change in some other thing inasmuch as it is other. He says this because it is possible for an active principle to be at the same time in the mobile or patient, as when something moves itself; although it is not mover and moved, or agent and patient, in the same respect. Hence the principle designated as active potency is said to be a principle of change in some other thing inasmuch as it is other; because, even though an active principle can be found in the same thing as a passive principle, this still does not happen insofar as it is the same, but insofar as it is other.
1777. That the other potencies are reduced to this principle which is called active potency is evident; for in one sense passive potency means the principle by which one thing is moved by some other thing inasmuch as it is other. He says this because, even if the same thing might be acted upon by itself, this still does not happen insofar as it is the same, but insofar as it is other. Now this potency is reduced to a first active potency, because when anything undergoes change this is caused by an agent. And for this reason passive potency is also reduced to active potency.
1778. In another sense potency means a certain state of insusceptibility (or impossibility) “to change for the worse,” i.e., a disposition whereby a thing is such that it cannot undergo change for the worse; i.e., that it cannot undergo corruption as a result of some other thing “inasmuch as it is other,” namely, by a principle of change which is an active principle.
1779. Now it is evident that both of these senses of potency imply something within us which is referred to the undergoing of a change. For (1) in the one sense the term designates a principle by reason of which someone cannot be acted upon; and (2) in the other sense it designates a principle by reason of which someone can be acted upon.
Hence, since the state of being acted upon depends on action, the definition “of the primary kind of potency,” namely, active potency, must be given in the definition of both senses of potency. Thus these two senses of potency are reduced to the first, namely, to active potency, as to something prior.
1780. Again, in another sense potencies are spoken of not only in relation to acting and being acted upon but in relation to what is done well in each case. For example, we say that someone is capable of walking, not because he can walk in any way at all, but because he can walk well; and in an opposite sense we say of one who limps that he cannot walk. Similarly, we say that wood is capable of being burned because it can be burned easily; but we say that green wood is incapable of being burned because it cannot be burned easily. Hence it is clear that in the definitions of those potencies which are described as potencies for acting and being acted upon well, there are included the concepts of those primary potencies which were described as potencies for acting and being acted upon without qualification; for example, to act is included in to act and to be acted upon is included in to be acted upon well.
Hence it is obvious that all of these senses of potency are reduced to one primary sense, namely, to active potency; and therefore it is also evident that this multiplicity is not the multiplicity of equivocation but of analogy.
1781. It is evident, then (744).
From what has been said he now indicates something that is true about the foregoing potencies. He says that in one sense the potency for acting and that for being acted upon are one, and in another sense they are not. (1) They are one potency if the relationship of the one to the other is considered; for one is spoken of in reference to the other. For a thing can be said to have a potency for being acted upon, either because it has of itself a potency by which it may be acted upon, or because it has a potency by which something else may be acted upon by it. And in this second sense active potency is the same as passive potency; for by reason of the fact that a thing has active potency it has a power by which something else may be acted upon by it.
1782. (2) However, if these two potencies—active and passive—are taken in reference to the subject in which they are found, then in this sense active and passive potency are different; for passive potency exists in a patient, since a patient is acted upon by reason of some principle existing within itself; and matter is of this sort. Now passive potency is nothing but the principle by which one thing is acted upon by another; for example, to be burned is to undergo a change, and the material principle by reason of which a thing is capable of being burned is the oily or the fat. Hence the potency itself is present as a passive principle in the thing capable of being burned. And similarly what yields to the thing touching it so that it receives an impression from it, as wax or something of this sort, is capable of doing so inasmuch as it is impressionable. “And the supposit,” i.e., the male, is the proper subject of the modification resulting in an eunuch. The same is true of other things which are acted upon insofar as they have within themselves a principle for being acted upon, which is called passive potency. But active potency is in the agent, as heat in the thing which heats and the art of building in the builder.
1783. And since active potency and passive potency are present in different things, it is obvious that nothing is acted upon by itself inasmuch as it is naturally disposed to act or to be acted upon. However, it is possible for something to be acted upon by itself accidentally, as a physician heals himself not inasmuch as he is a physician but inasmuch as he is ill. But in this case a thing is not acted upon by itself, because, properly speaking, one of the aforesaid principles is present in one and the same thing, and not the other. For the principle of being acted upon is not present in the one having the principle of action except accidentally, as has been said (1782).
1784. And incapacity (745).
Here he establishes the truth about incapacity, saying that incapacity (which is the contrary of the above-mentioned potency or capacity) or impossibility (which is referred to incapacity of this sort) is the privation of the potency in question.
However, he says this to distinguish it from the impossible which signifies some mode of falsity, which is not referred to any incapacity, just as the possible is also not referred to any potency. For since privation and possession belong to the same subject and refer to the same attribute, potency and incapacity must belong to the same subject and refer to the same attribute.
Hence there are as many senses of incapacity as there are of potency, to which it is opposed.
1785. But it must be noted that the term privation is used in many senses. For in one sense whatever does not have some attribute can be said to be deprived of it, as when we say that a stone is deprived of sight because it does not have sight; and in another sense a thing is said to be deprived only of what it can have and does not have. And this may happen in two ways: in one way when the thing does not have it at all, as a dog is said to be deprived of sight when it does not have it; and, in another way, if it does not have it when it is naturally disposed to have it. Hence a dog is not said to be deprived of sight before the ninth day. This sense of privation is again divided. For in one sense a thing is said to be deprived of some attribute because it does not have it in a particular way, namely, completely and well; as when we say that someone who does not see well is blind. And in another sense a thing is said to be deprived of some attribute when it does not have it in any way at all; for example, we say that a person is deprived of sight who does not have sight at all. But sometimes force is included in the notion of privation, and then we say that some things are deprived of certain attributes when those which they are naturally disposed to have are removed by force.
LESSON 2
Rational and Irrational Potencies
ARISTOTLE’S TEXT Chapter 2:1046a 36-1046b 28
746. And since some such principles are present in non-living things, and others in living things and in the soul, and in the soul having reason, it is evident that some potencies will be devoid of reason and others will be rational. And for this reason all the arts and productive sciences are potencies; for they are principles of change in some other thing inasmuch as it is other.
747. And all those potencies which are rational are open to contrary determinations, and those which are irrational are each determined to one thing; for example, what is hot is capable of heating, whereas the medical art is concerned with both sickness and health.
748. And the reason of this is that science is a conception [or rational plan], and the same conception explains both a thing and its privation, though not in the same way. And in one sense it is a conception of both, and in another it applies rather to the existent thing. Hence it is necessary that such sciences should deal with contraries, but with one directly and with the other indirectly; for the conception applies to one essentially, but to the other in a kind of accidental way, because it explains the contrary by negation and removal. For the contrary is the primary privation, and this is the removal of the other term.
749. Moreover, since contraries do not exist in the same subject, and since a science is a potency in a being which possesses a rational plan, and the soul has a principle of motion, it follows that, while what is healthful produces only health, and what is capable of heating produces only heat, and what is capable of cooling produces only cold, one who has a science may be occupied with both contraries. For reason extends to both but not in the same manner, and it exists in a soul which possesses a principle of motion Hence the soul will initiate both by the same principle by joining both to the same rational plan. And for this reason those things whose potency is rational produce effects contrary to those whose potency is irrational; for one principle of contrary determinations is contained in the rational plan.
750. It is also evident that a potency for doing something well involves the potency of merely doing something or undergoing some change. But the latter does not always involve the former; for he who does a thing well must do it, but he who does something need not do it well.
COMMENTARY
Subjects of potency
1786. Having explained the different senses in which the term potency is used, here the Philosopher establishes the truth about potency in relation to the things in which it is found. This is divided into two parts. In the first (1786) he shows how these potencies differ from each other on the basis of a difference in their subjects. In the second (1795) he shows how potency and actuality are simultaneous or not in a substance.
In regard to the first he does three things. First, he shows how potencies differ on the basis of a difference in their subjects. He says that, since potencies are principles both for acting and being acted upon, some of these principles are in non-living things and some in living ones. And since living things are composed of body and soul, and the principles for acting and being acted upon which are present in the body of living things do not differ from those in non-living ones, he therefore adds “and in the soul,” because the principles of action which are present in the soul clearly differ from those present in non-living things.
1787. Again, there are several kinds of souls, and many of these do not differ to any great extent both in acting and in being acted upon from non-living things which act by natural instinct; for the parts of the nutritive and sentient soul act by natural impulse. Now only the rational part of the soul has dominion over its acts, and it is in this respect that it differs from non-living things. Therefore, having pointed out the difference between souls, he adds “and in the soul having reason,” because those principles of living things which are found in the rational part of the soul differ specifically from those of non-living things. Hence it is evident that some powers of the soul are irrational and others rational.
1788. He explains what he means by those which are rational, when he adds that (1) “all the productive arts,” as the building and constructive arts and the like, whose actions pass over into (+) external matter, and (2) all sciences which do not perform actions that pass over into (~) external matter, as the moral and logical sciences—all arts of this kind, I say, are powers. And this is concluded from the fact that they are principles of change in some other thing inasmuch as it is other. This is the definition of active power, as is clear from what was said above.
1789. And all those (747).
Second, he gives the difference between the above-mentioned potencies. He says that the same rational potencies are (+) open to contrary determinations as the art of medicine, which is a potency, as has been explained (1404-7), can produce both health and sickness.
But irrational potencies are not (~) open to contrary determinations, but properly speaking each is determined to one thing; for example, the heat of the sun has as its proper effect to heat, although it can be the cause of coldness inasmuch as by opening the pores it causes the loss of internal heat; or by absorbing the matter of a hot humor it destroys the heat and thereby cools.
1790. And the reason (748).
Then the Philosopher gives the reason for the aforesaid difference, and it is as follows: a science, which is a rational potency, is a conception of the thing known existing in the mind. Now the same conception explains both the thing and its privation, although not in the same way, because it first makes known the existing thing and subsequently its privation; for example, the power of sight itself is known properly by means of the notion of sight, and then blindness is known, which is nothing but the very lack of sight in a thing naturally disposed to have it. Hence, if science is a conception of the thing known existing in the mind, the same science must deal with contraries—with one primarily and properly, and with the other secondarily; for example, the art of medicine is cognitive and productive primarily of health and secondarily of sickness, because, as has been pointed out, this art has to do with the conception of the thing known in the mind, and this conception is of one of the contraries directly and of the other indirectly.
1791. And since the remarks which the Philosopher had made above about privation he afterwards transferred to contraries, he shows that the same conception applies to a contrary and to a privation; for just as a privation is explained by negation and removal (for example, the removal of sight explains blindness), in a similar fashion a contrary is explained by negation and removal; because privation, which is merely the removal of some attribute, is a sort of first principle among contraries.
For in the case of all contraries one stands as something perfect and the other as something imperfect and the privation of the former; black, for example, is the privation of white, and cold is the privation of heat. Thus it is evident that the same science extends to contraries.
1792. Moreover, since (749).
He next develops this point, and he begins to give the reason for the aforesaid difference. For it is clear that natural things act by reason of the forms present in them. But contrary forms cannot exist in the same subject. Therefore it is impossible for the same natural thing to produce contrary effects.
But science is a potency for acting and a principle of motion, because a person has an idea of the thing to be made and this principle of motion is in the mind. And since this is so it follows that natural things produce only one effect; for example, what is healthful produces only health, and what is capable of heating produces only heat, and what is capable of cooling produces only cold.
But one who acts by science may be occupied with both contraries, because the conception of both contained in the soul is the same; for the soul possesses the principle of such motion, although not in the same way, as has been explained.
1793. Therefore, just as a natural activity proceeds to bring about its effect as though it were united to its form, which is the principle of action whose likeness remains in the effect, in a similar fashion the soul by its activity proceeds to bring about both opposites “by the same principle,” i.e., by the conception which is one for the two opposites, uniting both motions to this principle and causing both to terminate in it inasmuch as the likeness of this principle is verified in both of the opposites brought into being.
Therefore it is evident that rational powers produce an effect opposite to irrational powers, because a rational power produces contrary effects, whereas an irrational power produces only one effect. The reason is that a single principle of contrary effects is contained in the conception belonging to a science, as has been explained.
1794. It is also evident (750).
He explains the relationship of some of the senses of potency mentioned above to those which come under them. For it was stated above that a thing is said to have active or passive potency, sometimes only because it can act or be acted upon, and sometimes because it can act or be acted upon well. Therefore he says that the potency for acting or being acted upon well involves the potency for acting or being acted upon, but not the reverse. For it follows that someone acts if he acts well, but the opposite of this is not true.
LESSON 3
Rejection of the View That a Thing Has Potency Only When It Is Acting. Rejection of the View That All Things Are Possible
ARISTOTLE’S TEXT Chapters 3 & 4: 1046b 29-1047b 30
751. There are some, such as the members of the Megaric school, who say that a thing has a potency for acting only when it is acting, and that when it is not acting it does not have this potency; for example, one who is not building does not have the power of building, but only one who is building when he is building; and it is the same in other cases.
752. It is not difficult to see the absurd consequences of this position. For it is evident, according to this view, that a man will not be a builder if he is not building, because to be a builder is to be able to build. The same is true in the case of the other arts. Therefore, if it is impossible to have such arts unless one has at some time learnt and acquired them, and if it is impossible not to have them unless one has at some time lost them (either through forgetfulness or through some change or through the passage of time; for this cannot occur as a result of the object being destroyed, since it always exists), when one will have ceased to use an art he will not have it; and yet he will be able to build forthwith, thus somehow getting it back again.
753. And the same thing will be true in the case of non-living things; for neither the cold nor the hot nor the sweet nor the bitter nor any sensible thing will exist in any way at all if they are not being sensed. Hence they will have to maintain the theory that Protagoras did.
754. In fact nothing will have senses unless it is sensing or acting. Therefore, if that is blind which does not have the power of sight, though it is designed by nature to have it, and when it is designed by nature to have it, and so long as it exists, the same persons will be blind many times during the day; and deaf as well.
755. Further, if what is deprived of a potency is incapable, it will be impossible for that to come into being which has not yet been generated; but he who says that what cannot possibly be generated either is or will be, is in error; for this is what impossible or incapable means. Hence these theories do away with both motion and generation; for what is standing will always stand, and what is sitting will always sit, because if it is sitting it will not get up, since it is impossible for anything to get up which has no possibility of doing so.
756. Therefore, if it is impossible to maintain this, it is evident that potency and actuality are distinct. But these views make potency and actuality the same, and for this reason it is no small thing which they seek to destroy. Hence it is possible for a thing to be capable of being and yet not be, and for a thing not to be and yet be capable of being. And it is similar in the case of the other categories; for example, a thing may be capable of walking and yet not walk, and be capable of not walking and yet walk.
757. Moreover, a thing has a potency if there is nothing impossible in its having the actuality of that of which it is said to have the potency. I mean, for example, that if a thing is capable of sitting, and it turns out to be sitting, there will be nothing impossible in its having a sitting position; and it is similar if it is capable of being moved or of moving something, or of standing or causing a thing to stand, or of being or coming to be, or of not being or not coming to be.
758. And the word actuality, which is combined with entelechy, is extended chiefly from motion to other things; for actuality seems to be identified mainly with motion. And for this reason they do not assign motion to non-existent things, but they do assign the other categories. For example, non-existent things are considered the objects of intellect and desire but not to be in motion. And the reason is that they would have to exist actually even though they did not exist actually; for some non-existent things are potential. Yet they do not exist, because they do not exist in complete actuality.
Chapter 4
759. Now if what has been called potential or possible is such because something follows from it, it is evident that it cannot be true to say that a thing is possible but will not be, because things which cannot possibly be would then disappear. An example would be if someone, thinking that nothing is impossible, were to affirm that it is possible for the diagonal of a square to be commensurate, even though it is not commensurate; because nothing prevents a thing that is capable of being or of coming to be from not being or not coming to be. But this conclusion necessarily follows from the things laid down above. And if we suppose that which is not but is capable I of being, to be or to have come into being, nothing would be impossible. But in this case something impossible will occur; for it is impossible that a diagonal be commensurate. For to be false and to be impossible are not the same; for while it is false that you are now standing, it is not impossible.
760. And at the same time it is evident that, if when A exists B must exist, then if A is possible B must be possible; for if it is not necessary that B be possible, there is nothing to prevent its not being possible. Therefore, let A be possible. And if A is possible, then when A is possible, if A is assumed to exist, nothing impossible follows, but B necessarily exists. But this was supposed to be impossible. Therefore, let B be impossible. Then if B must be impossible, A must be so. But the first was supposed to be impossible; therefore so also is the second. Hence, if A is possible, B will be possible also, i.e., if they are so related that, when A exists, B must exist. Therefore, if when A and B are so related, B is not possible, then A and B will not be related in the way supposed. On the other hand, if, when A is possible, B must be possible, then if A exists, B must exist. For to say that B must be possible if A is possible, means that, if A exists both when it exists and in the way in which it is possible for it to exist, then B must also exist and exist in that way.
COMMENTARY
Objection 1: A thing has potency only when it is acting
1795. Having compared one kind of potency with another in the above discussion, here the Philosopher begins to explain how potency and actuality are found in the same subject. This is divided into two parts. In the first he rejects the false opinions of some men. In the second (1815) he establishes the truth (“And since among”).
The first is divided into two parts. In the first part he rejects the opinion of those who said that a thing is possible or potential only when it is in a state of actuality. In the second part (1810) he rejects the opinion of those who maintain the reverse of this: that all things are potential or possible, even though they are not in a state of actuality (“Now if what”).
In regard to the first he does two things. First, he rejects the erroneous opinion referred to. Second (1804), he explains what it is to be potential or possible, and what it is to be actual (“Moreover, a thing”).
In regard to the first he does three things. First, he gives this opinion. Second (1796), he destroys it (“It is not difficult”). Third (1803), he draws his intended conclusion (“Therefore, if it”).
He accordingly says, first, that some said that a thing is in a state of potency or capability only when it is acting; for example, a man who is not actually building is incapable of building, but he is capable of building only when he is actually building; and they speak in a similar way about other things.
The reason for this position seems to be that they thought that all things come about necessarily because of some connection between causes.
Thus if all things come about necessarily, it follows that those things which do not, are impossible.
1796. It is not difficult (752).
Then he adduces arguments against the above opinion, and these reduce it to its absurd consequences. The first is as follows: to be building is to have the power or capability of building. Therefore, if no one has the power or capability of acting except when he is acting, no one is a builder except when he is building. And the same thing will be true of the other arts; for all arts are certain capabilities or potencies, as has been pointed out (1786). It follows, then, that no one will have an art except when he is exercising it.
1797. But this is shown to be impossible if two assumptions are made. The first is this: if someone did not at first have an art, it would be impossible for him to have it later unless he had learned it or acquired it in some way, i.e., by discovery.
1798. The second assumption is that if someone had an art it would be impossible for him not to have the same art later unless he lost it in some way, either through forgetfulness or through some illness or through the passage of a long time during which the knowledge was not exercised; for this is the cause of forgetfulness. Now it cannot be that someone should lose an art as a result of the destruction of its object, as it sometimes happens that true knowledge is lost when a thing is changed; for example, when someone makes a true judgment that Socrates is sitting, his true judgment is destroyed when Socrates stands up. But this cannot be said about an art; for an art is not a knowledge of what exists, but of what is to be made; and so long as the matter from which an art can produce something continues to exist, the object of that art always exists. Hence an art cannot be lost when its object is destroyed, except in the ways mentioned.
1799. Now from these two assumptions the Philosopher argues as follows: if a man does not have an art except when he is exercising it, then when he begins to exercise it he has it anew. Therefore he must either have learned it or acquired it in some other way. And similarly when he ceases to exercise an art it follows that he lacks that art, and thus he loses the art which he previously had either through forgetfulness or through some change or through the passage of time. But both of these are clearly false; and therefore it is not true that someone has a potency only when he is acting.
1800. And the same (753).
Here he gives the second argument, which now has to do with the irrational principles present in non-living things, namely, hot and cold, sweet and bitter, and other qualities of this kind, which are active principles changing the senses and thus are potencies. Now if potency is present in a thing only when it is acting, it follows that nothing is hot or cold, sweet or bitter, and so forth, except when it is being sensed through a change in the senses. But this is clearly false; for if it were true it would follow that Protagoras’ opinion would be true, since he said that all the properties and natures of things have existence only in being sensed and in being thought.
And from this it would follow that contradictories would be true at the same time, since different men have contradictory opinions about the same thing. Now the Philosopher argued dialectically against this position above in Book IV (636). Therefore it is false that potency exists only when there is activity.
1801. Here he gives the third argument, which is as follows: sense is a kind of potency. Therefore, if potency exists only when there is activity, it follows that a man has sensory power only when he is sensing, for example, the power of sight or hearing. But one who does not have the power of sight although he is naturally disposed to have it is blind; and one who does not have the power of hearing is deaf. Hence he will be blind and deaf many times on the same day. But this is clearly false, for a blind man does not afterwards regain sight nor a deaf man hearing.
1802. Further, if what (755).
Here he gives the fourth argument, which is as follows: it is impossible for a thing to act which does not have the power to act. Therefore, if one has a potency or power only when he is acting, it follows that when he is not acting it is impossible for him to act. But whoever says that something incapable of happening either is or will be, is mistaken. This is evident from the meaning of the word impossible; for the impossible is said to be false because it cannot happen. It follows, then, that something which is not is incapable of coming to be in any way. And thus potency so understood will do away with motion and generation, because one who is standing will always stand, and one who is sitting will always sit. For if anyone is sitting, he will never stand afterwards, because so long as he is not standing he does not have the power to stand. Hence it is impossible for him to stand, and consequently it is impossible for him to get up. Similarly what is not white will be incapable of being white, and thus could not be made white. The same holds true in the case of all other things.
1803. Therefore, if (756).
He draws his intended conclusion, saying that, if the absurdities mentioned above cannot be admitted, it is obvious that potency and actuality are distinct. But those who hold the foregoing position make potency and actuality the same insofar as they say that something has potency only when it is in a state of actuality. And from this it is evident that they wish to remove from nature something of no little importance, for they eliminate motion and generation, as has been stated (1802). Hence, since this cannot be admitted, it is obvious that something is capable of being which yet is not, and that something is capable of not being which yet is. And “it is similar in the case of the other categories,” or predicaments, because it is possible from someone who is not walking to walk, and conversely it is possible from someone who is walking not to walk.
1804. Moreover, a thing (757).
Here he explains what it is to be potential and what it is to be actual. First, he explains what it is to be potential. He says that that is said to be potential from which nothing impossible follows when it is assumed to be actual; for example, if one were to say that it is possible for someone to sit if nothing impossible follows when he is assumed to sit. And the same holds true of being moved and of moving something, and other cases of this kind.
1805. And the word “actuality” (758).
Second, he explains what it is to be actual. He says that the word actuality is used to signify entelechy and perfection, namely, the form, and other things of this kind, as any action at all, is derived properly from motion, so far as the origin of the word is concerned. For since words are signs of intellectual conceptions, we first give names to those things which we first understand, even though they may be subsequent in the order of nature. Now of all acts which are perceived by us in a sensible way, motion is the best known and most evident to us; and therefore the word actuality was first referred to motion, and from motion the word was extended to other things.
1806. And for this reason motion is not attributed to (~) non-existent things, although certain of the other categories mentioned above are attributed to non-existents; for we say that non-existent things are intelligible, or thinkable, or even desirable, but we do not say that they are moved. For, since to be moved means to be actual, it follows that things which do not exist actually would exist actually; but this is obviously false. For even if some non-existent things are potential, they are still not said to be, since they are not actual.
Objection 2: All things are possible.
1807. Now if what (759).
Having destroyed the opinion of those who claim that nothing is possible except when it is actual, the Philosopher now destroys the opposite opinion of those who claim that all things are possible; and in regard to this he does two things. First, he destroys this opinion. Second (1810), he establishes a truth about the succession of possible things.
He accordingly says, first, that if it is true that a thing is said to be possible because something follows from it, inasmuch as the possible has been defined as that from which nothing impossible follows if it is assumed to exist, it is evident that the statements of some thinkers that anything is possible even if it never will be, cannot be true, since as a result of this position impossible things will be eliminated. For example, if one were to say that the diagonal of a square can be commensurate with a side, even though it is not commensurate with it (and one might speak in the same way about other impossible things), and not think that it is impossible for the diameter of a square to be commensurate with a side, those who maintain this position, I say, speak truly in one sense and in another they do not.
1808. For there are some things which nothing will prevent us from designating as capable or possible of coming to be, even though they never will be or ever come to be; but this cannot be said of all things. Yet according to the doctrine laid down above, and which we are now to assume, only those things are capable of being or coming to be, even though they are not, from which nothing impossible follows when they ate posited. However, when it is posited that the diagonal of a square is commensurate, an impossible conclusion follows. Thus it cannot be said that it is possible for the diagonal to be commensurate, for it is not only false but impossible.
1809. Now some things are false only but not impossible, as that Socrates sits or that he stands. For to be false and to be impossible are not the same; for example, it is false that you are now standing, but it is not impossible.
Therefore the foregoing opinion is true of some things, because some are possible even though they are false. However, it is not true of all things, because some are both false and impossible.
1810. And at the same (760).
And since he had said that a thing is judged possible because nothing impossible follows from it, he indicates the way in which there are possible consequents. He says that not only is the position in question destroyed by the definition of the possible given above, but it is also evident at the same time that, if the antecedent of a conditional proposition is possible, the consequent will also be possible; for example, if this conditional proposition “If when A is, B is,” is true, then if A is possible, B must be possible.
1811. Now in order to understand this we must note that the word possible is used in two senses: (1) It is used, first, in contradistinction to the necessary, as when we call those things possible which are capable either of being or not being. And when possible is taken in this way, the foregoing remarks do not apply. For nothing prevents the antecedent from being capable of being or not being, even though the consequent is necessary, as is clear in this conditional proposition, “If Socrates laughs, he is a man.”
1812. (2) The word possible is used in a second sense inasmuch as it is common both to those things which are necessary and to those which are capable of being or not being, according as the possible is distinguished from the impossible. And the Philosopher is speaking of the possible in this way here when he says that the consequent must be possible if the antecedent was possible.
1813. For let it be assumed that this conditional proposition is true: If A is, then B is; and let it be assumed that the antecedent, A, is possible. Then it is necessary that B either be possible or not. Now if it is necessary, then the assumption follows. But if it is not necessary, nothing prevents the opposite from being assumed, namely, that B is not possible. But this cannot stand; for A is assumed to be possible, and when it is assumed to be possible, it is at the same time assumed that nothing impossible follows from it; for the possible was defined above as that from which nothing impossible follows. But B follows from A, as was assumed, and B was assumed to be impossible; for to be impossible is the same as not to be possible. Therefore A will not be possible if B, which was held to be impossible, follows from it. Therefore let B be assumed to be impossible, and if it is impossible and given A, B must exist, then both the first and the second, namely, A and B will be impossible.
1814. In which place it must be noted that the following proposition is correct: (+) if the consequent is impossible, the antecedent is impossible; but (~) the reverse is not true. For nothing prevents something necessary from being a consequence of the impossible, as in this conditional proposition, “If man is an ass, he is an animal.”
Therefore what the Philosopher says here must not be understood as meaning that, if the first, i.e., the antecedent, were impossible, then the second, i.e., the consequent, would also be impossible. But it must be understood to mean that, if the consequent is impossible, both will be impossible.
Therefore it is obvious that, if A and B are so related that, when A is, B must be, it necessarily follows that, if A is possible, B will be possible; and if B is not possible when A is possible, then A and B are not related in the way supposed, namely, that B follows from A. But it is necessary that when A is possible B must be possible, if when A exists it is necessary that B exist. Therefore when I say “If A is, B is,” this means that B must be possible if A is possible, in the sense that it is possible for B to exist at the same time and in the way in which A is possible; for it is not possible that it should exist at any time and in any way.
LESSON 4
The Relative Priority of Actuality and Potency. The Reduction of Natural Potencies to Actuality
ARISTOTLE’S TEXT Chapter 5: 1047b 31-1048a 24
761. And since among all potencies some are innate, as the senses, and some are acquired by practice, as the power of playing the flute, and some by learning, as artistic powers, those which are acquired by practice and by the use of reason must be acquired by previous exercise. But this is not necessary in the case of those which are not such and which involve passivity.
762. Now that which is capable is capable of something at some time and in some way, and has all the other qualifications which must be included in the definition; and some things can cause motion according to a rational plan and their potencies are rational, whereas other things are devoid of any rational plan and their potencies are irrational. And the former potencies must exist in living things, whereas the latter exist in both kinds of things.
763. And since this is so, then in the case of the latter potencies, when the thing that is capable of acting and the one that is capable of being acted upon come close to each other, the one must act and the other be acted upon; but in the case of the former potencies this is not necessary.
764. For the latter are all productive of one effect, whereas the former are productive of contrary effects. Hence they would produce contrary effects at the same time, that is, if they were to act on a proximate patient without something determining them. But this is impossible.
765. Therefore there must be some other thing which is the proper cause of this, and by this I mean appetite or choice. For whatever a thing chiefly desires this it will do, when, insofar as it is potential, it is present and comes close to the thing which is capable of being acted upon. Hence every potency endowed with reason, when it desires something of which it has the potency and insofar as it has it, must do this thing. And it has this potency when the thing capable of being acted upon is present and is disposed in a definite way; but if it is not, it will not be able to act.
766. For it is unnecessary to add this qualification: when nothing external hinders it; for the agent has the potency insofar as it is a potency for acting. But this is not true of all things but only of those which are disposed in a definite way, in the case of which external obstacles will be excluded; for they remove some of the qualifications which are given in the definition of the capable or possible.
767. And for this reason if such things wish or desire to do two things or contrary things at the same time, they will not do them; for they do not have the potency for doing both at the same time, nor is it possible to do them at the same time, since it is those things which they have the capacity of doing that they do.
COMMENTARY
How potency precedes or follows act
1815. Having rejected the false opinions about potency and actuality the Philosopher now establishes the truth about them; and in regard to this he does two things. First, he shows how actuality is prior to potency in the same subject; and second (1816), how potency, when it is prior to actuality, is brought to a state of actuality.
He accordingly says, first, that, since (1) some potencies are innate in the things of which they are the potencies, as the sensory powers in animals; and (2) some are acquired by practice, as the art of flute-playing and other operative arts of this kind; and some are acquired by teaching and learning, as medicine and other similar arts; all of the abovementioned potencies which we have as a result of practice and the use of reason must first be exercised and their acts repeated before they are acquired. For example, one becomes a harpist by playing the harp, and one becomes a physician by studying medical matters.
But (1) other potencies which are not acquired by practice but which belong to us by nature and are passive, as is evident in the case of sensory powers, are not a result of exercise; for one does not acquire the sense of sight by seeing but actually sees because he has the power of sight.
1816. Now that which (762).
Here he shows how those potencies which are prior to actuality are brought to actuality; and in regard to this he does two things. First, he shows how different potencies—rational and irrational potencies—differ from each other in this respect. Second (1820), he shows how rational potencies are brought to a state of actuality (“Therefore, there must”).
In regard to the first he does three things. First, he lays down certain conditions required for the study of the aforesaid differences, and (1) one of these is that it is necessary to consider several qualifications in the definition of the capable or potential. For the capable does not refer to just anything at all but to something definite. Hence the capable must be capable of something, such as to walk or to sit. And similarly what can act or be acted upon cannot act or be acted upon at any time whatever; for example, a tree can bear fruit only at some definite time.
Therefore, when it is said that something is capable, it is necessary to determine when it is capable. And it is also necessary to determine in what way it is capable, for that which is capable can neither act nor be acted upon in every way; for example, one can walk in this way, namely, slowly, but not rapidly. And the same thing is true of the other qualifications which they are accustomed to give in the definitions of things, for example, by what instrument, in what place, and the like.
1817. Another qualification which he lays down is that (a) some things are capable of something because of a rational plan, and the potencies for these capabilities are rational. (b) But some capabilities are irrational, and the potencies for these are irrational. Again, rational potencies can exist only in living things, whereas irrational potencies can exist in both, i.e., in both living and nonliving things. And they exist not only in plants and in brute animals, which lack reason, but also in men themselves, in whom are found certain principles both of acting and of being acted upon which are irrational; for example, the powers of nutrition and growth, and weight, and other accidents of this kind.
1818. And since (763).
(2) Second, he gives the difference between the potencies in question.
He says that in the case of irrational potencies when the thing capable of being acted upon comes close to the thing which is capable of acting, then in accordance with that disposition whereby that able to be acted upon can be acted upon and that capable of acting can act, it is (+) necessary that the one be acted upon and that the other act. This is clear, for instance, when something combustible comes in contact with fire.
But in the case of rational potencies this is not necessary; for no matter how close some material may be brought to a builder, it is not (~) necessary that he build something.
1819. For the latter (764).
(3) Third, he gives the reason for the difference pointed out. (a) He says that irrational potencies are such that each is productive of only one effect, and, therefore, when such a potency is brought close to something that is capable of being acted upon, it must produce the one effect which it is capable of producing.
(b) But one and the same rational potency is capable of producing contrary effects, as was said above (1789-93). Therefore, if, when it is brought close to something capable of being acted upon, it would be necessary for it to bring about the effect which it is capable of producing, it would follow that it would produce contrary effects at the same time; but this is impossible. For example, it would follow that a physician would induce both health and sickness.
1820. Therefore there must (765).
He then shows what is necessary in order for rational potencies to begin to act, seeing that closeness to the thing capable of being acted upon is not sufficient. In regard to this he does three things.
First, he reveals the principle by which a rational potency is made to act. He concludes from the above discussions that since a rational potency has a common relationship to two contrary effects, and since a definite effect proceeds from a common cause only if there is some proper principle which determines that common cause to produce one effect rather than the other, it follows that it is necessary to posit, in addition to the rational power which is common to two contrary effects, something else which particularizes it to one of them in order that it may proceed to act. And this “is appetite or choice,” i.e., the choosing of one of the two, or the choice which involves reason; for it is what a man intends that he does, although this occurs only if he is in that state in which he is capable of acting and the patient is present. Hence, just as an irrational potency which is capable of acting must act when its passive object comes close to it, in a similar fashion every rational potency must act (a) when it desires the object of which it has the potency, and (b) in the way in which it has it. And it has the power of acting when the patient is present and is so disposed that it can be acted upon; otherwise it could not act.
1821. For it is unnecessary (766).
Second, he answers an implied question. For since he had said that everything capable of acting as a result of a rational plan, when it desires something of which it is the potency, acts of necessity on the patient before it, someone could ask why he did not add this qualification, namely, “when nothing external hinders it”; for it has been said that it must act if it has sufficient power to act. But this does not occur in any and every way, but only when the thing having the potency is disposed in some particular way; and in this statement external obstacles are excluded. For the things which hinder it externally remove some of it desires, and assuming that some the qualifications laid down in the common definition of the capable or possible, so that it is not capable at this time or in this way or the like.
1822. And for this (767).
Third, he instructs us to avoid the absurd conclusions which he first said would follow, namely, that a rational potency would produce contrary effects at the same time. For if it is necessary that a rational potency should do what it should wish either by reason or by sense appetite, and granted that it should wish to do two different or contrary things at the same time, it does not follow for this reason that they will do them. For they do not have power over contrary effects in such a way that they may do contrary things at the same time; but they act according to the way in which they have a potency, as has been explained (1816-20).
LESSON 5
Actuality and Its Various Meanings
ARISTOTLE’S TEXT Chapter 6: 1048a 25-1048b 36
768. Since we have dealt with the kind of potency which is related to motion, let us now determine about actuality both what it is and what kind of thing it is. For in making our distinctions it will become evident at the same time with regard to the potential not only that we speak of the potential as that which is disposed by nature to move something else or be moved by something else, either in an unqualified sense or in some special way, but also that we use the word in a different sense as well. And for this reason we will also come upon these points in making our investigations.
769. Now actuality is the existence of a thing not in the sense in which we say that a thing exists potentially, as when we say that Mercury is potentially in the wood, and a half in the whole, because it can be separated from it, or as we say that one who is not theorizing is a man of science if he is able to theorize; but in the sense in which each of these exists actually.
770. What we mean becomes evident in particular cases by induction, and we should not look for the boundaries of every thing, but perceive what is proportional; for it is as one who is building to one capable of building, and as one who is awake to one who is asleep, and as one who sees to one whose eyes are closed but who has the power of sight, and as that which is separated out of matter to matter, and as that which has been worked on to that which has not; and let actuality be defined by one member of this division and potency by the other.
771. However, things are not all said to be actual in the same way, but proportionally, as this is in that or to that; indeed, some are as motion to potency, and others as substance to some matter.
772. But the infinite and the void and all other such things are said to exist potentially and actually in a different sense from that which applies to many beings, for example, from that which sees or walks or is visible. For these things can be verified, and verified without qualification; for what is visible is so designated sometimes because it is being seen and sometimes because it is capable of being seen. But the infinite does not exist potentially in the sense that it will ever have actual separate existence, but it exists potentially only in knowledge. For since the process of division never comes to an end, this shows that this actuality exists potentially, but not that it ever exists separately.’ Therefore, regarding actuality, both what it is and what kind of thing it is will be evident to us from these and similar considerations.
COMMENTARY
Kinds of act
1823. Having drawn his conclusions about potency, Aristotle now establishes the truth about actuality; and this is divided into two parts. In the first he establishes what actuality is. In the second (1832) he establishes what is true when something is in potency to actuality.
In regard to the first he does two things. First, he links this up with the preceding discussion. He says that, since we have dealt with the kind of potency which is found in mobile things, i.e., the kind which is an active or passive principle of motion, we must now explain what actuality is and how it is related to potency; because when we will have distinguished the kinds of actuality, the truth about potency will become evident from this at the same time. For actuality is found not only in mobile things but also in immobile ones.
1824. And since potency is referred to actuality, it is evident from this that capability or potency taken in reference to action is attributed not only (1) to something that is naturally disposed (+) to move something else actively or be moved by something else passively, either in an unqualified sense, inasmuch as potency is referred alike to acting and being acted upon, or in some special way, inasmuch as potency is referred to what is able to act or be acted upon well; but (2) capability or potency is also referred to that actuality which is devoid of (~) motion. For although the word actuality is derived from motion, as was explained above (1805), it is still not motion alone that is designated as actuality. Hence, neither is potency referred only to motion. It is therefore necessary to inquire about these things in our investigations.
1825. Now actuality (769).
Second, he establishes the truth about actuality. First, he shows what actuality is; and second (1828), how it is used in different senses in the case of different things (“However, things”).
In regard to the first he does two things. First, he shows what actuality is. He says that a thing is actual when it exists but not in the way in which it exists when it is potential. (a) For we say that the image of Mercury is in the wood potentially and not actually before the wood is carved; but once it has been carved the image of Mercury is then said to be in the wood actually. (b) And in the same way we say that any part of a continuous whole is in that whole, because any part (for example, the middle one) is present potentially inasmuch as it is possible for it to be separated from the whole by dividing the whole; but after the whole has been divided, that part will now be present actually. (c) The same thing is true of one who has a science and is not speculating, for he is capable of speculating even though he is not actually doing so; but to be speculating or contemplating is to be in a state of actuality.
1826. What we mean (770).
Here he answers an implied question; for someone could ask him to explain what actuality is by giving its definition. And he answers by saying that it is possible to show what we mean (i.e., by actuality) in the case of singular things by proceeding inductively from examples, “and we should not look for the boundaries of everything,” i.e., the definition. For simple notions cannot be defined, since an infinite regress in definitions is impossible. But actuality is one of those first simple notions. Hence it cannot be defined.
1827. And he says that we can see what actuality is by means of the proportion existing between two things. For example, we may take the proportion of one who is building to one capable of building; and of one who is awake to one asleep; and of one who sees to one whose eyes are closed although he has the power of sight; and “of that which is separated out of matter,” i.e., what is formed by means of the operation of art or of nature, and thus is separated out of unformed matter, to what is not separated out of unformed matter. And similarly we may take the proportion of what has been prepared to what has not been prepared, or of what has been worked on to what has not been worked on. But in each of these opposed pairs one member will be actual and the other potential.
And thus by proceeding from particular cases we can come to an understanding in a proportional way of what actuality and potency are.
1828. However, things (771).
Then he shows that the term actuality is used in different senses; and he gives two different senses in which it is used. (1) First, actuality means action, or operation. And with a view to introducing the different senses of actuality he says, first, that we do not say that all things are actual in the same way but in different ones; and this difference can be considered according to different proportions. For a proportion can be taken as meaning that, just as one thing is in another, so a third is in a fourth; for example, just as sight is in the eye, so hearing is in the ear. And the relation of substance (i.e., of form) to matter is taken according to this kind of proportion; for form is said to be in matter.
1829. There is another meaning of proportion inasmuch as we say that, just as this is related to that, so another thing is related to something else; for example, just as the power of sight is related to the act of seeing, so too the power of hearing is related to the act of hearing. And the relation of motion to motive power or of any operation to an operative potency is taken according to this kind of proportion.
1830. But the infinite (772).
(2) Second, he gives the other sense in which the word actuality is used. He says that the infinite and the empty or the void, and all things of this kind, are said to exist potentially and actually in a different sense from many other beings; for example, what sees and what walks and what is visible. For it is fitting that things of this kind should sometimes exist in an unqualified sense either only potentially or only actually; for example, the visible is only actual when it is seen, and it is only potential when it is capable of being seen but is not actually being seen.
1831. But the infinite is not said to exist potentially in the sense that it may sometimes have separate actual existence alone; but in the case of the infinite, actuality and potentiality are distinguished only in thought and in knowledge. For example, in the case of the infinite in the sense of the infinitely divisible, actuality and potentiality are said to exist at the same time, because the capacity of the infinite for being divided never comes to an end; for when it is actually divided it is still potentially further divisible. However, it is never actually separated from potentiality in such a way that the whole is sometimes actually divided and is incapable of any further division.
And the same thing is true of the void; for it is possible for a place to be emptied of a particular body, but not so as to be a complete void, for it continues to be filled by another body; and thus in the void potentiality always continues to be joined to actuality.
The same thing is true of motion and time and other things of this kind which do not have complete being.
Then at the end he makes a summary of what has been said. This is evident in the text.
LESSON 6
Matter Is Potential When Ultimately Disposed for Actuality. The Use of the Term Matter in an Extended Sense
ARISTOTLE’S TEXT Chapter 7: 1048b 37-1049b 3
773. However, we must determine when each thing is in a state of potency and when it is not; for a thing is not potential at just any time at all; for example, in the process of generation is earth. potentially a man? Or is it not, but rather when it has become seed? But perhaps even this is not true in an unqualified sense.
774. Therefore, in like manner, it is not everything which will be healed by the art of medicine or by chance, but there is something which is capable of being healed, and this is what is potentially healthy. And the intelligible expression of what comes to exist actually after existing potentially as a result of intellect is that it is something which when willed comes to be if no external impediment hinders it. And in the other case, namely, in that of the thing which gets well by itself, health exists potentially when nothing within the thing hinders it. The same is true of those things which are potentially a house; for if there is nothing in these things, i.e., in the matter, which prevents them from becoming a house, and if there is nothing which must be added or taken away or changed, this is potentially a house. The same is true of all other things which have an external principle of generation. And in the case of those things which have their principle of change within themselves, a thing will also be potentially any of those things which it will be of itself if nothing external hinders this. For example, seed is not yet such, because it must be present in some other thing and be changed. But when it is already such as a result of its own principle, it is now this thing potentially; but in the other state it needs another principle; for example, earth is not yet a statue potentially, but when changed it becomes bronze.
775. Now it seems that the thing of which we are speaking is not a that but a “thaten”; for example, a chest is not wood but wooden; and wood is not earth but earthen. And the same thing would be true if earth were not something else but a “thaten.” And that other thing is always potentially (in an unqualified sense) the thing which follows it, as a chest is not earth or earthen but wooden; for this is potentially a chest and the matter of a chest; and wood in an unqualified sense is the matter of a chest in an unqualified sense; but this wood is the matter of this chest. And if there is some first thing which is not said to be “thaten” as regards something else, this is prime matter; for example, if earth is of air, and air is not fire but of fire, then fire is prime matter, and is a particular thing. For a universal and a subject differ in this respect that a subject is a particular thing.
776. For example, the subject of modifications is man, body and animal, whereas the modification is musical or white. And when music comes to a subject, the subject is not called music but musical; and a man is not called whiteness but white; and he is not called walking or motion but what walks or is moved, like a “thaten.”
777. Therefore all those modifying attributes which are predicated in this way have substance as their ultimate subject; whereas those which are not predicated in this way, but the predicate is a form or a particular thing, have matter and material substance as their ultimate subject. Therefore it is only fitting that the term “thaten” happens to be predicated of matter and the modifying attributes; for both are indeterminate. It has been stated, then, when a thing is said to exist potentially, and when it is not.
COMMENTARY
Potency proximate to act
1832. Having shown what actuality is, here the Philosopher intends to show both when and in virtue of what sort of disposition a thing is said to be in a state of potency for actuality. In regard to this he does two things.
First (1832), he states what he intends to do. He says that it is necessary to determine when a thing is in potency and when it is not. For it is not at just any time and when disposed in just any way that a thing can be said to be in potentiality even to what comes from it; for it could never be said that earth is potentially a man, since obviously it is not; but it is rather said to be potentially a man when the seed has already been generated from a preceding matter. And perhaps it never is potentially a man, as will be shown below.
1833. Therefore, in like manner (774).
Second, he answers the question which was raised; and in regard to this he does two things. First, he explains the sort of disposition which matter must have in order to be said to be in potency to actuality. Second (1839), he shows that it is only what is in matter that gets its name from matter disposed in some particular way.
In regard to the first it must be understood, as he said above in Book VII (1411), that the effects of certain arts may also come about without art; for while a house is not produced without art, health may be produced without the art of medicine through the operation of nature alone. And even though what comes to be by nature may not be fortuitous or a result of chance, since nature is an efficient cause in the proper sense, whereas fortune or chance is an efficient cause in an accidental sense, nevertheless, because the one who is healed by nature is healed without the application of any art, he is said to be healed by chance. For nothing prevents an effect which is not fortuitous in itself from being said to be fortuitous in relation to someone who does not consider the proper cause of such an effect.
1834. Hence he says that it is not just anyone at all or anyone disposed in any way at all who is healed by medicine or by chance; but it is someone having the capability by reason of a definite disposition who is healed either by nature or by art; for to all active principles there correspond definite passive principles. And it is the thing having this capability, which nature or art can bring to a state of actual health by a single action, that is potentially healthy.
1835. And in order that this kind of capability or potency may be more fully known he adds its definition both with reference to the operation of art and to that of nature. (1) Hence he says that the capable or potential is what comes to exist actually from existing potentially as a result of intellect or art. For “the intelligible expression,” or definition, of the capable is this: it is something which the artist immediately brings to actuality when he wills it if no external impediment hinders it. And the patient is then said to be potentially healthy, because he becomes healthy by a single action of art. (2) However, in the case of those who are healed by nature, each is said to be potentially healthy when there is nothing hindering health which has to be removed or changed before the healing power within the patient produces its effect in the act of healing.
1836. Now what we have said about the act of healing, which is brought about by the art of healing, can also be said about the other activities produced by the other arts. For matter is potentially a house when none of the things present in the matter prevent the house from being brought into being immediately by a single action, and when there is nothing that should be added or taken away or changed before the matter is formed into a house, as clay must be changed before bricks are made from it; and as something must be taken away from trees by hewing them and something added by joining them so that a house may be brought into being. Clay and trees, then, are not potentially houses, but bricks and wood already prepared are.
1837. And the same holds true in the case of other things whether their principle of perfection is outside of them, as in the case of artificial things, or within them, as in the case of natural things. And they are always in potency to actuality when they can be brought to actuality by their proper efficient principle without any external thing hindering them.
However, seed is not such, for an animal must be produced from it through many changes; but when by its proper active principle, i.e., something in a state of actuality, it can already become such, it is then already in potency.
1838. But those things which have to be changed before they are immediately capable of being brought to actuality require a different efficient principle, namely, the one preparing the matter, which is sometimes different from the one finishing it off, which induces the final form. For example, it is obvious that earth is not yet potentially a statue, for it is not brought to actuality by a single action or by a single agent; but first it is changed by nature and becomes bronze, and afterwards it becomes a statue by art.
1839. Now it seems (775).
Here he shows that a compound derives its name from such matter which is in potency to actuality; and in regard to this he does three things.
First, he shows how a compound derives its name from matter, saying that what is produced from matter is not called a that but a that-en (ecininum). This expression is not used in the Latin but it is used according to the custom of the Greeks to designate what comes from something else as from matter, as if to say that matter is not predicated abstractly of what comes from it, but derivately, as a chest is not wood but wooden; and as wood is not earth but earthen. And, again, if earth should have another matter prior to it, earth would not be that matter but “that-en,” i.e., it will not be predicated of earth abstractly but derivatively.
1840. Yet such predication is made, because what is potential in a definite way is always predicated of the thing which immediately comes after it. For example, earth, which cannot be said to be potentially a chest, is not predicated of a chest either abstractly or derivatively; for a chest is neither earth nor earthen but wooden, because wood is potentially a chest and the matter of a chest. Wood in general is the matter of a chest in general, and this particular wood is the matter of this particular chest.
1841. But if there is some first thing which is not referred to something else as a “that-en,” i.e., something which does not have something else predicated of it derivatively in the above way, this will be first matter. For example, if air is the matter of earth, as some have said (86), air will be predicated derivatively of earth, so that earth will be said to be of air (or airy). And similarly air will be said to be of fire and not fire, if fire is its matter. But if fire does not get its name from any prior matter, it will be first matter according to the position of Heraclitus (87). But here it is necessary to add “if it is something subsistent” in order to distinguish it from a universal; for a universal is predicated of other things but other things are not predicated of it—yet it is not matter, since it is not something subsistent. For a universal and a subject differ in that a subject is a particular thing whereas a universal is not.
1842. For example (776).
Second, he gives an example of derivative predication, saying that just as the subject of modifications, for example, man, body, or animal, has modifications predicated of it derivatively, in a similar fashion matter is predicated derivatively of that which comes from matter. Now “the modification is musical and white”; but the subject to which music accrues is not called music in the abstract, but is called musical derivatively; and man is not called whiteness but white. Nor again is man called walking or motion in the abstract, but what walks or is moved “as a that-en,” i.e., what gets a name [from something else].
1843. Therefore all (777).
Third, he compares both methods of giving names to things. He says that all those names which are predicated derivatively in this way, as the accidents mentioned, have substance as the ultimate subject which sustains them; but in all those cases in which the predicate is not derivative but is a form or a particular thing, such as wood or earth, in such predications the ultimate subject sustaining the rest is matter or material substance. And it is only fitting “that the term ‘that-en’ happens to be predicated” derivatively “of matter and the modifying attributes,” i.e., accidents, both of which are indeterminate. For an accident is both made determinate and defined by means of its subject, and matter by means of that to which it is in potency. Lastly he summarizes his remarks, and this part is evident.
LESSON 7
The Conceptual and Temporal Priority of Actuality to Potency and Vice Versa
ARISTOTLE’S TEXT Chapter 8: 1049b 4-1050a 3
778. Since we have established the different senses in which the term prior is employed (457), it is evident that actuality is prior to potency. And by potency I mean not only that definite kind which is said to be a principle of change in another thing inasmuch as it is other, but in general every principle of motion or rest. For nature also belongs to the same thing, since it is in the same genus as potency; for it is a principle of motion, although not in another thing but in something inasmuch as it is the same. Therefore actuality is prior to all such potency both in intelligibility and in substance; and in time it is prior in one sense, and in another it is not.
779. It is evident, then, that actuality is prior to potency in intelligibility; for what is potential in a primary sense is potential because it is possible for it to become actual. I mean, for example, that it is what is capable of building that can build, and what is capable of theorizing that can theorize, and what is capable of being seen that can be seen. And the same reasoning also applies in the case of other things; and therefore it is necessary that the conception or knowledge of the one should precede that of the other.
780. And actuality is prior to potency in time in the sense that an actuality which is specifically but not numerically the same as a potency is prior to it. I mean that the matter and & seed and the thing capable of seeing, which are a man and grain and seeing potentially but not yet actually, are prior in time to this man and to grain and to the act of seeing which exist actually. But prior to these are other actually existing things from which these have been produced; for what is actual is always produced from something potential by means of something which is actual. Thus man comes from man and musician from musician; for there is always some primary mover, and a mover is already something actual. And in our previous discussions (598; 611) concerning substance it was stated that everything which comes to be is produced from something, and this is specifically the same as itself.
781. And for this reason it seems to be impossible that anyone should be a builder who has not built something, or that anyone should be a harpist who has not played the harp. And the same holds true of all others who are learning; for one who is learning to play the harp learns to play it by playing it. And the same holds true in other cases.
782. From this arose the sophistical argument that one who does not have a science will be doing the thing which is the object of this science; for one who is learning a science does not have it.
783. But since some part of what is coming to be has come to be, and in general some part of what is being moved has been moved (as became evident in our discussions on motion), perhaps one who is learning a science must have some part of that science. Hence it is also clear from this that actuality is prior to potency both in the process of generation and in time.
COMMENTARY
Priority of act in time
1844. Having established the truth about potency and actuality, the Philosopher now compares one with the other; and this is divided into two parts. In the first part he compares them from the viewpoint of priority and posteriority; in the second (1883), in terms of being better or worse; and in the third (1888), in reference to knowledge of the true and the false.
In regard to the first he does two things. First, he explains his aim, saying that, since it has been established above, in Book V (936), that the term prior is used in different senses, it is evident that actuality is prior to potency in different ways. And we are now speaking of potency not only inasmuch as it is a principle of motion in some other thing as other, as active potency was defined above (1776), but universally of every principle, whether it be a principle that causes motion or a principle of immobility or rest or a principle of action devoid of motion (e.g., understanding), because nature also seems to belong to the same thing as potency.
1845. For nature is in the same genus as potency itself because each is a principle of motion, although nature is not a principle of motion in some other thing but in the thing in which it is present as such, as is made clear in Book Il of the Physics. However, nature is a principle not only of motion but also of immobility.
Hence actuality is prior to all such potency both in intelligibility and in substance. And in one sense it is also prior in time, and in another it is not.
1846. It is evident (779).
Second he proves his thesis. First, he shows that actuality is prior to potency in intelligibility. Second (1847), he shows how it is prior in time, and how it is not. Third (1856), he shows how it is prior in substance.
The first is proved as follows: anything that must be used in defining something else is prior to it in intelligibility, as animal is prior to man and subject to accident. But potency or capability can only be defined by means of actuality, because the first characteristic of the capable consists in the possibility of its acting or being actual. For example, a builder is defined as one who can build, and a theorist as one who can theorize, and the visible as what can be seen; and the same is true in other cases. The concept of actuality must therefore be prior to the concept of potency, and the knowledge of actuality prior to the knowledge of potency. Hence Aristotle explained above what potency is by defining it in reference to actuality, but he could not define actuality by means of something else but only made it known inductively.
1847. And actuality (780).
Then he shows how actuality is prior to potency in time, and how it is not. In regard to this he does two things. First, he makes this clear in the case of passive potencies; and second (1850), in the case of certain active potencies.
He accordingly says, (+) first, that actuality is prior to potency in time in the sense that in the same species the agent, or what is actual, is prior to what is potential; but (~) in numerically one and the same thing what is potential is prior in time to what is actual.
1848. This is shown as follows: if we take this man who is now actually a man, prior to him in time there was a matter which was potentially a man. And similarly seed, which is potentially grain, was prior in time to what is actually grain. And “the thing capable of seeing,” i.e., having the power of sight, was prior in time to the thing actually seeing. And prior in time to the things having potential being there were certain things having actual being, namely, agents, by which the former have been brought to actuality. For what exists potentially must always be brought to actuality by an agent, which is an actual being. Hence what is potentially a man becomes actually a man as a result of the man who generates him, who is an actual being; and similarly one who is potentially musical becomes actually musical by learning from a teacher who is actually musical. And thus in the case of anything potential there is always some first thing which moves it, and this mover is actual.
It follows, then, that even though the same thing numerically exists potentially prior in time to existing actually, there is still also some actual being of the same species which is prior in time to the one that exists potentially.
1849. And because someone could be perplexed about some of the statements which he had made, he therefore adds that these have been explained above; for it was pointed out in the foregoing discussions about substance—in Book VII (1383; 1417)—that everything which comes to be comes from something as matter, and by something as an agent. And it was also stated above that this agent is specifically the same as the thing which comes to be. This was made clear in the case of univocal generations, but in the case of equivocal generations there must also be some likeness between the generator and the thing generated, as was shown elsewhere (1444-47).
1850. And for this reason (781).
He explains the temporal sequence of actuality and potency in the case of certain active potencies; and in regard to this he does three things.
First, he explains what he intends to do. For it was said above (1815) that there are certain operative potencies whose very actions must be understood to be performed or exercised beforehand, as those acquired by practice or instruction. And with regard to these he says here that in those things which are numerically the same, actuality is also prior to potency. For it seems impossible that anyone should become a builder who has not first built something; or that anyone should become a harpist who has not first played the harp.
1851. He draws this conclusion from the points laid down above; for it was said above (1848) that one who is potentially musical becomes actually musical as a result of someone who is actually musical—meaning that he learns from him; and the same thing holds true of other actions. Now one could not learn an art of this kind unless he himself performed the actions associated with it; for one learns to play the harp by playing it. This is also true of the other arts. It has been shown, then, that it is impossible to have potencies of this sort unless their actions are also first present in one and the same subject numerically.
1852. From this arose (782).
Second, he raises a sophistical objection against the above view. He says that “a sophistical argument arose,” i.e., an apparently cogent syllogism which contradicts the truth, and it runs as follows: one who is learning an art exercises the actions of that art. But one who is learning an art does not have that art. Hence one who does not have a science or an art is doing the thing which is the object of that science or art. This seems to be contrary to the truth.
1853. But since some (783).
Third, he answers this objection by stating a position which was discussed and proved in the Physics, Book VI; for there he proved that being moved is always prior to having been moved, because of the division of motion. For whenever any part of a motion is given, since it is divisible, we must be able to pick out some part of it which has already been completed, while the part of the motion given is going on. Therefore whatever is being moved has already been partly moved.
1854. And by the same argument, whatever is coming to be has already partly come to be; for even though the process of producing a substance, with reference to the introduction of the substantial form, is indivisible, still if we take the preceding alteration whose terminus is generation, the process is divisible, and the whole process can be called a production. Therefore, since what is coming to be has partly come to be, then what is coming to be can possess to some degree the activity of the thing in which the production is terminated. For example, what is becoming hot can heat something to some degree, but not as perfectly as something that has already become hot. Hence, since to learn is to become scientific, the one learning must already have, as it were, some part of a science or an art. It is not absurd, then, if he should exercise the action of an art to some degree; for he does not do it as perfectly as one who already has the art.
1855. But in reason itself there are also naturally inherent certain seeds or principles of the sciences and virtues, through which a man can pass to some degree into the activity of a science or a virtue before he has the habit of the science or the virtue; and when this has been acquired he acts perfectly, whereas at first he acted imperfectly. Lastly he summarizes the above discussion, as is evident in the text.
LESSON 8
Priority of Actuality to Potency in Substance
ARISTOTLE’S TEXT Chapter 8: 1050a 4-1050b 6
784. But actuality is also prior in substance; (1) because those things which are subsequent in generation are prior in form and substance; for example, man is prior to boy, and human being to seed; for the one already has its form, but the other has not.
785. And (2) because everything which comes to be moves toward a principle, namely, its goal [or end]. For that for the sake of which a thing comes to be is a principle; and generation is for the sake of the goal. And actuality is the goal, and it is for the sake of this that potency is acquired.
786. For animals do not see in order that they may have the power of sight, but they have the power of sight in order that they may see.
787. And similarly men have the science of building in order that they may build, and they have theoretical knowledge in order that they may speculate; but they do not speculate in order that they may have theoretical knowledge, unless they are learning by practice. And these latter do not speculate [in a perfect way], but either to some degree or because they do not need to speculate.
788. Further, matter is in potency up to the time at which it attains its form; but when it exists actually, it then possesses its form. And the same holds true in the case of other things, even of those whose goal is motion. And for this reason, just as those who are teaching think that they have reached their goal when they exhibit their student performing, so it is with nature.
789. For if this were not so, Pauson’s Mercury would exist again, because it would not be more evident whether scientific knowledge is internal or external, as is the case with the figure of Mercury. For the activity is the goal, and the actuality is the activity. And for this reason the term actuality is used in reference to activity and is extended to completeness.
790. But while in the case of some things the ultimate effect is the use (as, for example, in the case of sight the ultimate effect is the act of seeing, and no other work besides this results from the power of sight), still from some potencies something else is produced; for example, the art of building produces a house in addition to the act of building. Yet in neither case is the act any less or any more the end of the potency; for the act of building is in the thing being built, and it comes into being and exists simultaneously with the house. Therefore in those cases in which the result is something other than the use, the actuality is in the thing being produced; for example, the act of building is in the thing being built, and the act of weaving in the thing being woven. The same holds true in all other cases. And in general, motion is in the thing being moved. But in the case of those things in which nothing else is produced besides the activity, the activity is present in these, as the act of seeing is in the one seeing, and the act of speculating in the one speculating, and life in the soul. Accordingly, happiness is in the soul, for it is a kind of life.
791. It is evident, then, that substance or form is actuality. Hence it is clear according to this argument that actuality is prior to potency in substance. And, as we have said (780), one actuality is always prior to another in time right back to that actuality which is always the first principle of motion.
COMMENTARY
Priority of act substantially
1856. Having shown that actuality is prior to potency in intelligibility and in one sense in time, the Philosopher now shows that it is prior in substance. This was the third way given above (1845) in which actuality is prior to potency.
This is divided into two parts. In the first part he proves his thesis by arguments taken from things which are sometimes potential and sometimes actual. In the second part (1867) he proves his thesis by comparing eternal things, which are always actual, with mobile things, which are sometimes actual and sometimes potential (“But actuality”).
And since to be prior in substance is to be prior in perfection, and since perfection is attributed to two things, namely, to the form and to the goal [or end], therefore in the first part he uses two arguments to prove his thesis. The first of these pertains to the form, and the second (1857) to the goal, given at the words, “And because.”
He accordingly says, first, that actuality is prior to potency not only in intelligibility and in time “but in substance,” i.e., in perfection; for the form by which something is perfected is customarily signified by the term substance. This first part is made clear by this argument: those things which are subsequent in generation are “prior in substance and form,” i.e., in perfection, because the process of generation always goes from what is imperfect to what is perfect; for example, in the process of generation man is subsequent to boy, because man comes from boy; and human being is subsequent to seed. The reason is that man and human being already have a perfect form, whereas boy and seed do not yet have such a form.
Hence, since in numerically one and the same subject actuality is subsequent to potency both in generation and in time, as is evident from the above, it follows that actuality is prior to potency in substance and in intelligibility.
1857. And (2) because (785).
Here he proves the same point by an argument involving the goal of activity. First, he sets forth the argument. Second (1858), he explains one of the principles assumed in his argument (“For animals”). Third (1862), he settles an issue which could cause difficulty in the above argument (“But while”).
He accordingly says, first, that everything which comes to be when it moves towards its goal moves towards a principle. For a goal, or that for the sake of which a thing comes to be, is a principle because it is the first thing intended by an agent, since it is that for the sake of which generation takes place. But actuality is the goal of potency, and therefore actuality is prior to potency and is one of its principles.
1858. For animals (786).
He now explains the position which he maintained above, namely, that actuality is the goal of potency. He makes this clear, first, in the case of natural active potencies. He says (~) that animals do not see in order that they may have the power of sight, but (+) they rather have the power of sight in order that they may see. Thus it is clear that potency exists for the sake of actuality and not vice versa.
1859. And similarly (787).
Second, he makes the same thing clear in the case of rational potencies. He says that men have the power of building in order that they may build; and they have “theoretical knowledge,” or speculative science, in order that they may speculate. However, they do not speculate in order that they may have theoretical knowledge, unless they are learning and meditating about those matters which belong to a speculative science in order that they may acquire it. And these do not speculate perfectly but to some degree and imperfectly, as has been said above (1853-55), because speculation is not undertaken because of some need but for the sake of using science already acquired. But there is speculation on the part of those who are learning because the need to acquire science.
1860. Further, matter (788).
Third he makes the same point clear in the case of passive potencies. He says that matter is in potency until it receives a form or specifying principle, but then it is first in a state of actuality when it receives its form. And this is what occurs in the case of all other things which are moved for the sake of a goal. Hence, just as those who are teaching think they have attained their goal when they exhibit their pupil whom they have instructed performing those activities which belong to his art, in a similar fashion nature attains its goal when it attains actuality. Hence it is made evident in the case of natural motion that actuality is the goal of potency.
1861. For if this were not (789).
Fourth, he proves his thesis by an argument from the untenable consequences. He says that if a thing’s perfection and goal do not consist in actuality, there would then seem to be no difference between someone wise, as Mercury was, and someone foolish, as Pauson was. For if the perfection of science were not in the one acting, Mercury would not have exhibited it in his own science, if he had “internal scientific knowledge,” i.e., in reference to its internal activity, “or external,” i.e., in reference to its external activity, as neither would Pauson. For it is by means of the actual use of scientific knowledge, and not by means of the potency or power, that one is shown to have a science; because activity is the goal of a science, and activity is a kind of actuality.
And for this reason the term actuality is derived from activity, as has been stated above (1805); and from this it was extended to form, which is called completeness or perfection.
1862. But while (790).
He explains a point which could cause a difficulty in the foregoing argument. For since he had said that some product is the goal of activity, one could think that this is true in all cases. But he denies this, saying that the ultimate goal or end of some active potencies consists in the mere use of those potencies, and not in something produced by their activity; for example, the ultimate goal of the power of sight is the act of seeing, and there is no product resulting from the power of sight in addition to this activity. But in the case of some active potencies something else is produced in addition to the activity; for example, the art of building also produces a house in addition to the activity of building.
1863. However, this difference does not cause actuality to be the goal of potency to a lesser degree in the case of some of these potencies and to a greater degree in the case of others; for the activity is in the thing produced, as the act of building in the thing being built; and it comes into being and exists simultaneously with the house. Hence if the house, or the thing built, is the goal, this does not exclude actuality from being the goal of potency.
1864. Now it is necessary to consider such a difference among the aforesaid potencies, because (1) when something else is produced besides the actuality of these potencies, which is activity, the activity of such potencies is in the thing being produced and is their actuality, just as the act of building is in the thing being built, and the act of weaving in the thing being woven, and in general motion in the thing being moved.
And this is true, because when some product results from the activity of a potency, the activity perfects the thing being produced and not the one performing it. Hence it is in the thing being produced as an actuality and perfection of it, but not in the one who is acting.
1865. But (2) when nothing else is produced in addition to the activity of the potency, the actuality then exists in the agent as its perfection and does not pass over into something external in order to perfect it; for example, the act of seeing is in the one seeing as his perfection, and the act of speculating is in the one speculating, and life is in the soul (if we understand by life vital activity). Hence it has been shown that happiness also consists in an activity of the kind which exists in the one acting, and not of the kind which passes over into something external; for happiness is a good of the one who is happy, namely, his perfect life. Hence, just as life is in one who lives, in a similar fashion happiness is in one who is happy. Thus it is evident that happiness does not consist either in building or in any activity of the kind which passes over into something external, but it consists in understanding and willing.
1866. It is evident (791).
Lastly he retraces his steps in order to draw the main conclusion which he has in mind. He says that it has been shown from the above discussion that a thing’s substance or form or specifying principle is a kind of actuality; and from this it is evident that actuality is prior to potency in substance or form. And it is prior in time, as has been stated above (1848), because the actuality whereby the generator or mover or maker is actual must always exist first before the other actuality by which the thing generated or produced becomes actual after being potential.
And this goes on until one comes to the first mover, which is actuality alone; for whatever passes from potency to actuality requires a prior actuality in the agent, which brings it to actuality.
LESSON 9
The Substantial Priority of Actuality in Incorruptible Things
ARISTOTLE’S TEXT Chapter 8: 1050b 6-1051a 3
792. But actuality is prior to potency in a more fundamental sense; for eternal things are prior in substance to corruptible ones, and nothing eternal is potential.
793. The reason of this is that every potency is at the same time a potency for opposite determinations. For what is incapable of existing does not exist in any way; and it is possible for everything that is capable of existing not to exist actually. Therefore whatever is ca able of existinly may either be or not be, and thus the same thing is capable both of being and of not being. But what is capable of not being may possibly not be; and what may possibly not be is corruptible: either absolutely, or in the sense in which it is said to be possible for it not to be, either according to place or to quantity or to quality. And the term absolutely means in reference to substance.
794. Therefore nothing that is incorruptible in an absolute sense is potential in an absolute sense. But there is nothing that hinders it from being so in other respects, for example, in reference to quality or to place. Therefore all incorruptible things are actual.
795. And none of those things which exist necessarily are potential. In fact such things are the first; for if they did not exist, nothing would exist.
796. Nor is eternal motion potential, if there be such a thing; and if anything is moved eternally, it is not moved potentially except in reference to whence and whither. And nothing prevents the matter of this sort of thing from existing.
797. And for this reason the sun and the stars and the entire heaven are always active, and there is no need to fear, as the natural philosophers do, that they may at some time stand still. Nor do they tire in their activity; for in them there is no potency for opposite determinations, as there is in corruptible things, so that the continuity of their motion should be tiresome. For the cause of this is that their substance is matter and potency and not actuality.
798. Moreover, incorruptible things are imitated by those which are in a state of change, such as fire and earth; for these latter things are always active, since they have motion in themselves and of themselves.
799. But all other potencies which have been defined are potencies for opposite determinations; for what is capable of moving something else in this way is also capable of not moving it in this way, i.e., all those things which act by reason. And irrational potencies will also be potencies for opposite determinations by being absent or not.
800. If, then, there are any natures or substances such as those thinkers who in their theories proclaim the Ideas to be, there will be something much more scientific than science itself, and something much more mobile than motion itself; for the former will rather be the actualities and the latter the potencies of these. Hence it is evident that actuality is prior to potency and to every principle of change.
COMMENTARY
Act prior in incorruptible things
1867. Aristotle proved above that actuality is prior to potency in substance, definition and perfection, by arguments drawn from corruptible things themselves; but here he proves the same point by comparing eternal things with corruptible ones.
This part is divided into two members. In the first (1867) he proves his thesis; and in the second (1882), by the thesis thus proved, he rejects a certain statement made by Plato (“If, then”).
In regard to the first he does two things. First, he proves his thesis. This he does by the following argument: eternal things are compared to corruptible ones as actuality to potency; for eternal things as such are not in potency, whereas corruptible things as such are in potency. But eternal things are prior to corruptible ones in substance and perfection; for this is evident (1856). Hence actuality is prior to potency both in substance and perfection. He says that his thesis is proved in a more proper way by this argument, because actuality and potency are not considered in the same subject but in different ones, and this makes the proof more evident.
1868. The reason (793).
Second, he proves one assumption which he made, namely, that nothing eternal is in potency; and in regard to this he does two things. First, he gives an argument to prove this, and it runs as follows: every potency is at one and the same time a potency for opposite determinations. Now he does not say this about active potency, for it has already been shown (1789) that irrational potencies are not potencies for opposite determinations; but he is speaking here of passive potency, on the basis of which a thing is said to be capable of being and not being either absolutely or in a qualified sense.
1869. Now the claim which he made he proves by an argument to the contrary; because where such potency does not exist, neither of the opposite determinations is possible; for what is incapable of being never exists in any way. For if a thing is incapable of being, it is impossible for it to be, and it is necessary for it not to be. But what is capable of being may possibly not be actual. Hence it is evident that what is capable of being may either be or not be; and thus the potency is at one and the same time a potency for opposite determinations, because the same thing is in potency both to being and non-being.
1870. But what is capable of not being may possibly not be, for these two statements are equivalent ones. Moreover, what may possibly not be is corruptible either absolutely or in a qualified sense inasmuch as it is said to be possible for it not to be. For example, if it is possible for some body not to be in place, that body is corruptible as far as place is concerned; and the same applies to quantity and quality. But that is corruptible in an absolute sense which is capable of not existing substantially. Therefore it follows that everything potential inasmuch as it is potential is corruptible.
1871. Therefore nothing (794).
Second, he draws from the foregoing the conclusion at which he aims; and in regard to this he does three things. First, he concludes to this thesis about eternal things, inferring from the observations made above that, if everything potential is corruptible, it follows that nothing which is incorruptible in an absolute sense is a potential being, provided that we understand incorruptible things in an absolute sense and potential being (~) in an absolute sense in reference to substance.
1872. But nothing prevents something that is incorruptible in an absolute sense from being potential (+) in a qualified sense, in reference either to quality or to place. For example, the moon is in a state of potency to being illuminated by the sun; and when the sun is in the east it is in a state of potency with regard to being in the west. It is evident from what has been said, then, that all eternal things as such are actual.
1873. And none (795).
Second, he comes to the same conclusion about necessary things as he did about eternal things, because even in corruptible things there are certain necessary aspects; for example, man is an animal, and every whole is greater than its part. Hence he says that nothing necessary is potential; for necessary things are always actual and incapable of being or not being. And those things which are necessary are the first of all things, because if they ceased to exist, none of the others would exist; for example, if essential predicates, which are referred to a subject necessarily, were taken away, accidental predicates, which can be present and not present in some subject, could not be present in any subject. It follows, then, that actuality is prior to potency.
1874. Nor is (796).
Third, he comes to the same conclusion about eternal motion as he did about eternal substances; and in regard to this he does three things. First, from what has been said above he concludes to his thesis. He says that, if some motion is eternal, that motion is not potential; nor is anything that is moved eternally in a state of potency to motion, but it is in a state of potency to this or to that place, i.e., inasmuch as it goes from this place to that place. For since motion is the actuality of something in potency, everything which is being moved must be in potency to the goal of that motion, not however as regards motion itself, but as regards some place to which it tends by its motion.
1875. And since what is being moved must have matter, he adds that nothing prevents a thing which is being moved by an eternal motion from having matter; because, even though it is not in potency to motion in an absolute sense, it is nevertheless in potency to this or to that place.
1876. And for this (797).
Second, he draws a corollary from the above discussion. For since what is being moved by an eternal motion is not in potency to motion itself (and the motion of the heavens is eternal according to the discussion in Book VIII of the Physics), it follows that the sun and the moon and the stars and the entire heaven are always active, because they are always being moved and are acting by means of their motion.
1877. Nor is it to be feared that at some time the motion of the heavens may cease, as “some of the natural philosophers feared it would,” namely, Empedocles and his followers, who held that at times the world is destroyed by discord and is restored again by friendship. Hence he says that this is not to be feared, because they are not potentially immobile.
1878. And for this reason too incorruptible things insofar as they are being moved do not tire in their activity, because “the potency for opposite determinations” is not found in them, namely, the ability to be both moved and not moved, as is found in corruptible things, which have these as a result of motion. And thus in this way continuous motion becomes laborious for them. For corruptible things labor insofar as they are moved; and the reason is that they are in a state of potency both for being moved and not being moved, and it is not proper to them by reason of their substantial nature always to be undergoing motion. Hence we see that the more laborious any motion is, the nearer also does the nature of the thing come to immobility; for example, in the case of animals it is evident that motion in an upward direction is more laborious.
1879. Now what he says here about the continuity of celestial motion is in keeping with the nature of a celestial body, which we know by experience.
But this is not prejudicial to the divine will, on which the motion and being of the heavens depend.
1880. Moreover, incorruptible things (798).
Third, he compares corruptible bodies with incorruptible ones from the viewpoint of activity. First, he does this insofar as they are alike. He says that the bodies of those things whose being involves change resemble incorruptible bodies insofar as they are always acting; for example, fire, which of itself always produces heat, and earth, which of itself always produces proper and natural activities. And this is true because they have motion and their own proper activity of themselves— inasmuch, namely, as their forms are principles of such motions and activities.
1881. But all the other (799).
Second, he compares them insofar as they are unlike. He says that in contrast with eternal things, which are always actual, the other potencies of mobile things, about which the truth has been established above, are all potencies for opposite determinations. But this is verified in a different way; for (1) rational potencies are potencies capable of opposite determinations because they can move in this way or not, as has been said above (1789); whereas (2) irrational potencies, though acting in one way, are themselves also potencies of opposite determinations in view of the fact that they can be present in a subject or not; for example, an animal can lose its power of vision.
1882. If, hen (800).
As a result of what has been said he rejects a doctrine of Plato. For Plato claimed that there are certain separate Forms, which he held to have being in the highest degree; say, a separate science, which he called science-in-itself; and he said that this is foremost in the class of knowable entities. And similarly he maintained that motion-in-itself is foremost in the class of mobile things. But according to the points made clear above, something else besides science-in-itself will be first in the class of knowable things; for it was shown that actuality is prior to potency in perfection, and science itself is a kind of potency. Hence speculation, which is the activity of science, will be more perfect than science is; and the same will apply in the case of other things of this kind. Lastly he summarizes his discussion, saying that actuality is prior to potency and to every principle of motion.
LESSON 10
The Relative Excellence of Actuality and Potency
ARISTOTLE’S TEXT Chapter 9: 1051a 4-1051a 33
801. Furthermore, that actuality is also better and more excellent and more honorable than good potency is evident from the following: all things which are spoken of as potential are alike capable of contrary determinations; for example, what is said to be capable of being well is the same as what is capable of being ill, and simultaneously has both capabilities; for it is the same potency that is capable of being well and being ill, and of being at rest and in motion, and of building and demolishing, and of being built and being demolished. Therefore the capacity for contrary determinations belongs to the same thing at the same time; but it is impossible for contrary determinations to belong to the same thing at the same time, for example, being well and ailing. Hence one of these must be good; but the potency may be both alike or neither; and therefore the actuality is better.
802. And also in the case of evil things the goal or actuality must be worse than the potency; for it is the same potency that is capable of both contraries.
803. It is clear, then, that evil does not exist apart from things; for evil is by its very nature subsequent to potency.
804. Hence in those things which exist from the very beginning and are eternal, there is neither evil nor wrong nor corruption; for corruption belongs to evil things.
805. And it is also by activity that geometrical constructions are discovered, because they are discovered by dividing. For if they had already been divided, they would be evident; but they are now present potentially. Why, for example, are the angles of a triangle equal to two right angles? Because the angles grouped around one point are equal to two right angles. Hence, if the line next to the one side were extended, the answer would be clear to anyone seeing the construction. Again, why is an angle in a semicircle always a right angle? Because, if its three lines are equal, two of which form the base and the other rests upon the middle point of the base, the answer will be evident to anyone who sees the construction and knows the former proposition. Hence, it is evident that constructions which exist potentially are discovered when they are brought to actuality; and the reason is that the intellectual comprehension of a thing is an actuality. Hence the potency proceeds from an actuality, and it is because people make these constructions that they attain knowledge of them. For in a thing numerically one and the same, actuality is subsequent in the order of generation.
COMMENTARY
Act is better in good things
1883. Having compared actuality and potency from the viewpoint of priority and posteriority, the Philosopher now compares them from the viewpoint of good and evil; and in regard to this he does two things.
First, he says that in the case of good things actuality is better than potency; and this was made clear from the fact that the potential is the same as what is capable of contrary determinations; for example, what can be well can also be ill and is in potency to both at the same time. The reason is that the potency for both is the same—for being well and ailing, and for being at rest and in motion, and for other opposites of this kind. Thus it is evident that a thing can be in potency to contrary determinations, although contrary determinations cannot be actual at the same time. Therefore, taking each contrary pair separately, one is good, as health, and the other evil, as illness. For in the case of contraries one of the two always has the character of something defective, and this pertains to evil.
1884. Therefore what is actually good is good alone. But the potency may be related “to both” alike, i.e., in a qualified sense—as being in potency. But it is neither in an absolute sense—as being actual. It follows, then, that actuality is better than potency; because what is good in an absolute sense is better than what is good in a qualified sense and is connected with evil.
1885. And also (802).
Second, he shows on the other hand that in the case of evil things the actuality is worse than the potency; and in regard to this he does three things.
First, he proves his thesis by the argument introduced above; for what is evil in an absolute sense and is not disposed to evil in a qualified sense is worse than what is evil in a qualified sense and is disposed both to evil and to good. Hence, since the potency for evil is not yet evil, except in a qualified sense (and the same potency is disposed to good, since it is the same potency which is related to contrary determinations), it follows that actual evil is worse than the potency for evil.
1886. It is clear, then (803).
Second, he concludes from what has been said that evil itself is not a nature distinct from other things which are good by nature; for evil itself is subsequent in nature to potency, because it is worse and is farther removed from perfection. Hence, since a potency cannot be something existing apart from a thing, much less can evil itself be something apart from a thing.
1887. Hence in those (804).
Third, he draws another conclusion. For if evil is worse than potency, and there is no potency in eternal things, as has been shown above (1867), then in eternal things there will be neither evil nor wrong nor any other corruption; for corruption is a kind of evil. But this must be understood insofar as they are eternal and incorruptible; for nothing prevents them from being corrupted as regards place or some other accident of this kind.
1888. And it is (805).
Having compared potency and actuality from the viewpoint of priority and posteriority and from that of good and evil, be now compares them with reference to the understanding of the true and the false. In regard to this he does two things. First (805:C 1888), he compares them with reference to the act of understanding; and second (806:C 1895), with reference to the true and the false (“Now the terms”).
He accordingly says, first (805), that “geometrical constructions,” i.e., geometrical descriptions, “are discovered,” i.e., made known by discovery in the actual drawing of the figures. For geometers discover the truth which they seek by dividing lines and surfaces. And division brings into actual existence the things which exist potentially; for the parts of a continuous whole are in the whole potentially before division takes place. However, if all had been divided to the extent necessary for discovering the truth, the conclusions which are being sought would then be evident. But since divisions of this kind exist potentially in the first drawing of geometrical figures, the truth which is being sought does not therefore become evident immediately.
1889. He explains this by means of two examples, and the first of these has to do with the question, “Why are the angles of a triangle equal to two right angles?” i.e., why does a triangle have three angles equal to two right angles? This is demonstrated as follows.
Let ABC be a triangle having its base AC extended continuously and in a straight line. This extended base, then, together with the side BC of the triangle form an angle at point C, and this external angle is equal to the two interior angles opposite to it, i.e., angles ABC and BAC. Now it is evident that the two angles at point C, one exterior to the triangle and the other interior, are equal to two right angles; for it has been shown that, when one straight line falls upon another straight line, it makes two right angles or two angles equal to two right angles. Hence it follows that the interior angle at the point C together with the other two interior angles which are equal to the exterior angle, i.e., all three angles, are equal to two right angles.
1890. This, then, is what the Philosopher means when he says that it may be demonstrated that a triangle has two right angles, because the two angles which meet at the point C, one of which is interior to the triangle and the other exterior, are equal to two right angles. Hence when an angle is constructed which falls outside of the triangle and is formed by one of its sides, it immediately becomes evident to one who sees the arrangement of the figure that a triangle has three angles equal to two right angles.
1891. The second example has to do with the question, “Why is every angle in a semicircle a right angle?” This is demonstrated as follows.
Let ABC be a semicircle, and at any point B let there be an angle subtended by the base AC, which is the diameter of the circle. I say, then, that angle B is a right angle. This is proved as follows: since the line AC is the diameter of the circle, it must pass through the center. Hence it is divided in the middle at the point D, and this is done by the line DB. Therefore the line DB is equal to the line DA, because both are drawn from the center to the circumference. In the triangle DBA, then, angle B and angle A are equal, because in every triangle having two equal sides the angles above the base are equal. Thus the two angles A and B are double the angle B alone. But the angle BDC, since it is exterior to the triangle, is equal to the two separate angles A and B. Therefore angle BDC is double the angle B alone.
1892. And it is demonstrated in the same way that angle C is equal to angle B of the triangle BDC, because the two sides DB and DC are equal since they are drawn from the center to the circumference, and the exterior angle, ADB, is equal to both. Therefore it is double the angle B alone. Hence the two angles ADB and BDC are double the whole angle ABC. But the two angles ADB and BDC are either right angles or equal to two right angles, because the line DB falls on the line AC. Hence the angle ABC, which is in a semicircle, is a right angle.
1893. This is what the Philosopher means when he says that the angle in a semicircle may be shown to be a right angle, because the three lines are equal, namely, the two into which the base is divided, i.e., DA and DC, and the third line, BD, which is drawn from the middle of these two lines and rests upon these. And it is immediately evident to one who sees this construction, and who knows the principles of geometry, that every angle in a semicircle is a right angle.
1894. Therefore the Philosopher concludes that it has been shown that, when some things are brought from potency to actuality, their truth is then discovered. The reason for this is that understanding is an actuality, and therefore those things which are understood must be actual. And for this reason potency is known by actuality. Hence it is by making something actual that men attain knowledge, as is evident in the constructions described above. For in numerically one and the same thing actuality must be subsequent to potency in generation and in time, as has been shown above.
LESSON 11
The Reference of Truth and Falsity to Actuality. The Exclusion of Falsity from Simple and Eternal Things
ARISTOTLE’S TEXT Chapter 10: 1051a 34-1052a 11
806. Now the terms being and non-being are used in one sense with reference to the categorical figures; and in another with reference to the potentiality or actuality of these or their contraries; and in still another sense they are referred most properly to truth and falsity.
807. And in things this consists in being combined or being separated. Hence he who thinks that what is separated is separated, and that what is combined is combined, is right; but he who thinks about things otherwise than as they are, is wrong. And it is necessary to consider what we mean when we say that truth and falsity exist or do not exist. For it is not because we are right in thinking that you are white that you are white, but it is because you are white that in saying this we speak the truth.
808. Therefore, if some things are always combined and it is impossible for them to be separated, and others are always separated and it is impossible for them to be combined, and others admit of both contraries, then being consists in being combined and being one, and non-being consists in not being combined and being many. Therefore with regard to contingent things the same opinion or statement becomes true and false, and it is possible for it at one time to be true and at another to be false. But with regard to those things which are incapable of being otherwise than as they are, an opinion is not sometimes true and sometimes false, but one. is always true and the other always false.
809. However, with regard to things which are not composite, what is being and non-being, and what is truth and falsity? For such things are not composite so as to exist when combined and not exist when separated; for example, the proposition “The wood is white,” or the proposition “The diagonal is incommensurable.” Nor will truth and falsity still be present in them in the same way as in other things. And just as truth is not the same in these things, in a similar fashion neither is being the same.
810. But truth or falsity is as follows: to come in contact with a thing and to express it is truth (for expression is not the same as affirmation), and not to come in contact with a thing is ignorance. For it is impossible to be deceived about a thing’s quiddity, except in an accidental sense; and the same holds true in the case of incomposite things, for it is impossible to be deceived about them.
811. And they are all actual and not potential, for otherwise they would be generated and corrupted. But being itself is neither generated nor corrupted; otherwise it would be generated out of something. Therefore, regarding all those things which are really quiddities and actualities, it is impossible to be deceived about them, but one must either know them or not. But concerning them we may ask what they are, namely, whether they are such and such or not.
812. Now considering being in the sense of truth and non-being in the sense of falsity, in the case of composite beings there is truth if the thing is combined with the attribute attributed to it; in the case of simple beings the thing is just simply so. And if a thing is truly a being, it is so in some particular way; but if it is not, it does not exist at all. Again, truth means to know these beings, and there is neither falsity nor deception about them but only ignorance; but not ignorance such as blindness is, for blindness is as if one did not have intellective power at all.
813. And concerning immobile things it is also evident that there is no deception about them as regards time, if one assumes that they are immobile. For example, if one assumes that a triangle does not change, he will not be of the opinion that at one time its angles are equal to two right angles and that at another time they are not; for otherwise it would change. But he might assume that one thing has such and such a property and that another has not; for example, one might assume that no even number is a prime number, or that some are and some are not. But this is impossible as regards one single number; for one will not assume that one thing is such and another is not; but whether he speaks truly or falsely, a thing is always disposed in the same way.
COMMENTARY
Truth and falsehood
1895. Here the Philosopher compares actuality to potency with reference to truth and falsity; and in regard to this he does three things. First, he claims that truth and falsity are chiefly referred to actuality. Second (1896), he explains what he aims to do (“And in things”). Third (1917), he draws a corollary (“And concerning”).
He accordingly says, first, that, since being and non-being, which is its opposite, are divided in two ways: first, into the different categories—substance, quantity, quality and so forth; and second, into the potency and actuality of one or the other of contraries (since either one of two contraries may be actual or potential), it follows that true and false are most properly predicated of what is actual.
1896. And in things (807).
He now proves his thesis; and in regard to this he does three things. First, he makes this clear in the case of continuous substances; and second (1901), in that of simple substances (“However, with regard”). Third (1914), he summarizes both of these (“Now considering”).
In regard to the first he does two things. First, he explains his thesis, saying that in things “this,” i.e., being true or false, consists merely in being combined or being separated. Hence one who thinks that to be separated which is separated in reality, has a true opinion—for example, one who thinks that man is not an ass. And the same is true of one who thinks that to be combined which is combined in reality—for example, one who thinks that man is an animal. But, on the other hand, one who relates things in thought in a different way than they are in their own proper nature has an erroneous opinion—for example, one who thinks that man is an ass, or that he is not an animal—because when a thing is or is not, it is then said to be true or false.
1897. This must be understood as follows: you are not white because we think truly that you are white; but conversely we think you are white because you are white. Hence it has been shown that the way which a thing is disposed is the cause of truth both in thought and in speech.
1898. He adds this in order to clarify what he said above, namely, that in things truth and falsity consist in being combined and being separated. For the truth and falsity found in speech and in thought must be traced to a thing’s disposition as their cause. Now when the intellect makes a combination, it receives two concepts, one of which is related to the other as a form; hence it takes one as being present in the other, because predicates are taken formally.
Therefore, if such an operation of the intellect should be traced to a thing as its cause, then in composite substances the combination of matter and form, or also the combination of subject and accident, must serve as the foundation and cause of the truth in the combination which the intellect makes in itself and expresses in words. For example, when I say, “Socrates is a man,” the truth of this enunciation is caused by combining the form humanity with the individual matter by means of which Socrates is this man; and when I say, “Man is white,” the cause of the truth of this enunciation is the combining of whiteness with the subject. It is similar in other cases. And the same thing is evident in the case of separation.
1899. Therefore (808).
Second, he concludes from what has been said that, if the combining and separating of a thing is the cause of the truth and falsity in thought and in speech, the difference between truth and falsity in thought and in speech must be based on the difference between the combining and separating of what exists in reality. Now in reality such difference is found to involve combination and separation, because (1) some things are always combined and it is impossible for them to be separated; for example, sentient nature is always united to the rational soul, and it is impossible for the latter to be separated from the former in such a way that the rational soul may exist without the power of sensation, although on the other hand a sentient soul can exist without reason. Again, (2) some things are separated and it is impossible for them to be combined, for example, black and white, and the form of an ass and that of a man. Again, (3) some things are open to contraries, because they can be combined and separated, as man and white and also running.
1900. However, the being in which the intellect’s act of combining consists, inasmuch as there is affirmation, indicates a certain composition and union; whereas non-being, which negation signifies, does away with composition and union and indicates plurality and otherness. Hence it was shown that in the case of things which may be combined and separated one and the same statement is sometimes true and sometimes false; for example, the statement “Socrates is sitting” is true when he is sitting; but the same statement is false when he gets up. And the same holds true in the case of thought.
But with regard to those things which cannot be otherwise than they are, i.e., those which are always combined or separated, it is impossible for the same thought or statement to be sometimes true and sometimes false; but what is true is always true, and what is false is always false; for example, the proposition “Man is an animal” is true, but the proposition “Man is an ass” is false.
1901. However, with regard (809).
He now explains how truth and falsity can be present in simple things; and in regard to this he does three things. First, he shows that truth is not present in the same way in simple things and in composite ones. He says that in the case of things which are not composite but simple, such as immaterial substances, truth or falsity is not present in them (~) as a result of any combination or separation which occurs in reality, but (+) arises because their quiddity is known or not known. For when we acquire knowledge of the quiddity of any simple being, the intellect seems to be true; and when we fail to acquire knowledge of its quiddity, but attribute something else to it, the intellect is then false.
1902. For there is no composition in simple beings as a consequence of which it could be said that, when the thing is combined, the intellect in making a combination is then true; or that, when that is separated in reality which the intellect combines, the intellect is then not true. Or to express this in a different way, there is no composition in simple things by reason of which, when we express affirmatively that it is so, its composition is signified; and when we express negatively that it is not so, its separation is signified; as, for example, in the case of composite things, when it is said that a piece of wood is white, its composition is signified, or when it is said that it is not white, or that the diagonal is not commensurable, its separation is signified.
1903. Thus it is evident that truth and falsity are not present in simple things in the same way as in composite things. Nor is this surprising, since being also is not the same in both; but the being of composite things results from their components, whereas that of simple things does not. Now truth follows being, because, as was said in Book II (298) of this work, the structure of things in being and in truth is the same.
Hence those things which are not similar in being are not similar in truth.
1904. But truth (810).
Second, he shows how truth and falsity are present in simple things. He says that in the case of simple things truth and falsity are such as will be explained; for to come in contact with a simple thing through the intellect, in such a way as to apprehend what it is “and to express it,” i.e., to signify this simple thing by a word, constitutes the truth present in simple things. And since sometimes the word “to express” is taken for affirmative predication, which involves composition, he rejects this interpretation. He says that affirmation and expression are not the same, because affirmation occurs when one thing is predicated of something else, and this implies combination, whereas expression is the simple utterance of something.
1905. Therefore to come in contact with simple things through the intellect and to express them constitutes truth; but not to come in contact with them is not to know them at all. For whoever does not grasp the quiddity of a simple thing is completely ignorant of it; because one cannot both know and not know something about it, since it is not composite.
1906. Moreover, since he had said that to come in contact with simple things is to express their truth, it would seem that not to come in contact with them is (~) to be false or in error. He did not say this, however, but said that not to come in contact with them is (+) not to know them.
Hence he gives the reason why not to come in contact with them is not to be in error about them, saying that it is possible to be in error about their quiddity only accidentally; and this must be understood as follows.
1907. It was said above in Book VII (1362) and in Book VIII (1710) that in the case of simple substances the thing itself and its quiddity are one and the same. Hence, since a simple substance is its own quiddity, the judgment about the knowledge of a simple substance and the judgment about the knowledge of its quiddity are one and the same. But the intellect is deceived about a quiddity only accidentally; for either a person comes in contact with a thing’s quiddity through his intellect, and then he truly knows what that thing is; or he does not come in contact with it, and then he does not know what it is. Hence, with regard to such a thing the intellect is neither true nor false. This is why Aristotle says in Book III of The Soul that, just as a sense is always true with regard to its proper object, in a similar fashion the intellect is always true with regard to its proper object—quiddity.
And the fact that the intellect is not deceived about a thing’s quiddity applies not only in the case of simple substances but also in that of composite ones.
1908. Now it is necessary to consider how one may be accidentally deceived about a quiddity. For a person is deceived about a quiddity only as a result of combining or separating; and with regard to composite substances this may occur in two ways. (1) First, it may occur by combining a definition with something defined or by separating them; for example, if someone were to say that an ass is a mortal rational animal, or that a man is not a mortal rational animal, both would be false. (2) Second, insofar as a definition is composed of parts which are incompatible with each other; for example, if someone were to give this definition—man is a non-sensible animal. Thus a definition is said to be false in the first way because it is not the definition of this thing; and in the second way it is said to be false in itself, as the Philosopher has instructed us above in Book V (1132).
1909. Now we can be deceived accidentally about the quiddity of simple substances only in the first way; for their quiddity is not composed of many parts in the combining and separating of which falsity can arise.
1910. And they are (811).
He adapts his remarks about simple substances to his main thesis, in which he shows that truth involves actuality rather than potency. Indeed, he had shown this to be true in the case of composite substances insofar as their truth embodies combination and separation, which designate actuality. But he shows that this is true in the case of simple substances from the fact that they do not contain falsity but only truth. And for this reason they are not potential but actual.
1911. He accordingly says that all simple substances are actual beings and are never potential ones; for if they were sometimes actual and sometimes potential, they would be generated and corrupted. But this cannot be the case, as has been shown above (1715), for substances of this kind are forms alone, and for this reason they are also beings of themselves. Now what exists of itself is neither generated nor corrupted, for everything that is generated is generated from something.
But being in an absolute sense cannot be generated from anything; for there is nothing apart from being but only apart from some particular being, just as there is some being apart from man. Hence this being can be generated in a qualified sense, but being in an absolute sense cannot.
Hence what is a being of itself, because it is a form, from which being naturally follows, cannot be generated; and for this reason it is not sometimes potential and sometimes actual.
1912. Therefore, since truth consists chiefly in actuality, it is unfitting that there should be error or falsity in all those things which are actual only and are what something truly is, since they are quiddities or forms; but they must either be understood if they are grasped by the intellect, or not be understood at all if they are not grasped by the intellect.
1913. But even though it is impossible to be (~) deceived about these things as regards their essence, this is nevertheless (+ possible when “we ask what they are,” i.e., whether they are of such and such a nature or not. Hence it is possible to be deceived about them accidentally, as someone might ask whether a simple substance is fire or a corporeal substance or not, because if it is held to be a corporeal substance, there will be falsity accidentally as a result of combination.
1914. Now considering (812).
He summarizes the statements he has made about truth and falsity both with reference to composite things and to simple ones. He says that this being which signifies truth and non-being which signifies falsity (because he who says that a man is white signifies this to be true; and he who says that a man is not white signifies this to be false), being and non-being in this sense, I say, are used (1) in one way in the case of the composition of things. That is, there is truth if what the intellect combines is combined in reality, but there is falsity if what the intellect combines when it understands or forms a proposition is not combined in reality.
1915. (2) And truth exists in a different way in the case of simple things, if what is truly a being,” i.e., the quiddity or substance of a simple thing, is as it is understood to be; but if it is not as it is understood to be, no truth exists in the intellect. Thus truth consists in understanding these things; but concerning them there is neither falsity nor error in the intellect, as has been explained (1912), but ignorance; for if one does not grasp the quiddity of a thing, one does not know that thing in any way at all. In the case of composite things, however, one can know one of their properties and be deceived about the others.
1916. Furthermore, he shows what sort of ignorance this is when he says that this ignorance is not “a privation such as blindness,” which is the privation of the power of sight. Hence that ignorance would be similar to blindness if one did not have the intellective power of acquiring knowledge of simple substances.
And from this it is evident that according to the opinion of Aristotle the human intellect can acquire an understanding of simple substances. This is a point which he seems to have left unsolved in The Soul, Book III:3.
1917. And concerning (813).
Here he introduces a corollary. He says that it is evident from what has been said that there is no error about (~) immobile things as regards time. But in the case of (+) contingent things, which are not always so, it is possible to be in error about them as regards time; for example, if Socrates is going to sit down and someone were to judge this to be so, he could be deceived insofar as he might judge that Socrates is going to sit down when he is not. The same thing would be true if someone were to think that an eclipse will occur when it will not. But in the case of immobile things and those which always are, the above can occur only in one way, i.e., if someone were to think that these things are mobile and that they do not always exist; for he is then in error about them, but he would not be in error as regards time. Hence he says that, if someone thinks that they are immobile, he will not be deceived about them as regards time.
1918. He says this, then, because, if someone assumes that they are immobile, he will not think that they sometimes are and sometimes are not, and thus he is not deceived about them as regards time. For example, if someone thinks that a triangle is unchangeable, he will not be of the opinion that the sum of its angles will sometimes equal two right angles and sometimes will not, for it would then be both changeable and unchangeable.
1919. But in the case of immobile things it is possible to consider under one common aspect one thing that has such and such a property and another that has not; for example, it is possible to understand that under triangle some triangles are equilateral and others are not. And it is possible to ask whether no even number is prime, or whether some are and some are not—a prime number being one which the unit alone measures. Hence among even numbers only the number two is a prime number, but none of the others.
And regarding what is numerically one, in the case of immobile things it is impossible to be in error or to be deceived even in this [taking one thing that has and another that has not a certain property]. For in the case of something numerically one it is impossible for anyone to think that one individual can be so and another not be so; for what is numerically one is not divided into many. Hence he will have to say what is true or false in an unqualified sense, since what is numerically one always exists in the same way and is incapable of being diversified either in point of time or of subjects. From this it is clear that truth has to do with actuality; for immobile things as such are always actual.
SUMMARY
| Accident: | —Operation —Habit —Faculty | |
| Substance: | —Existence | |
| —Essence | —Form —Matter | |