CP 5: Pragmatism and Pragmaticism

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CP 5.320 Fn P1 p 191:

The word suppositio is one of the useful technical terms of the middle ages which was condemned by the purists of the renaissance as incorrect. The early logicians made a distinction between significatio and suppositio. [Cf. Prantl, II, 286ff; III, 51f.] Significatio is defined as “rei per vocem secundum placitum representatio.” [Ibid., footnote 199.] It is a mere affair of lexicography, and depends on a special convention (secundum placitum), and not on a general principle. Suppositio belongs, not directly to the vox, but to the vox as having this or that significatio. “Unde significatio prior est suppositione et differunt in hoc, quia significatio est vocis, suppositio vrto est termini jam compositi ex voce et significatione.” [Ibid., footnote 201.] The various suppositiones which may belong to one word with one significatio are the different senses in which the word may be taken, according to the general principles of the language or of logic. Thus, the word table has different significationes in the expressions “table of logarithms” and “writing-table”; but the word man has one and the same significatio, and only different suppositiones, in the following sentences: “A man is an animal,” “a butcher is a man,” “man cooks his food,” “man appeared upon the earth at such a date,” &c. Some later writers have endeavored to make “ acceptio ” do service for “ suppositio “; but it seems to me better, now that scientific terminology is no longer forbidden, to revive supposition. I should add that as the principles of logic and language for the different uses of the different parts of speech are different, supposition must be restricted to the acceptation of a substantive. The term copulatio was used for the acceptation of an adjective or verb.

William Wallace, O.P., also discusses ex suppositione reasoning in depth, esp. as it relates Aristotle, St. Thomas, Galileo, and modern scientific demonstrative reasoning (cf. Fr. Wallace's article "Albertus Magnus on Suppositional Necessity in the Natural Sciences" in Albertus Magnus and the Sciences: Commemorative Essays.

St. Vincent Ferrer also wrote a treatise on supposition.

Chapter 5: Truth (ref:20.1-20.28): 1902 | Truth and Falsity and Error (§3. Definitons of Truth) | CP 5.570-3

CP 8 ref:32.59: "The psychological versions of Peirce’s categories of First, Second, and Third are discussed in [CP] 7.524-538"; cf. also 5.290 (ref:10.74):

290. Thus, we have in thought three elements: first, the representative function which makes it a representation; second, the pure denotative application, or real connection, which brings one thought into relation with another; and third, the material quality, or how it feels, which gives thought its quality. †P1