In De ente et essentia D. Thomae Aquinatis commentaria

Whether matter is part of the natural quiddity.

Concerning the foregoing, it is questioned whether matter is part of natural quiddity. In this question I shall do three things: first, set forth the opinion of the Commentator; second, set forth the opinion of St. Thomas; third, answer the opposing arguments. As to the first, the Commentator, in Metaphysics VI, commentaries XXI and XXXIV, holds that matter is not part of natural quiddity, but falls into the definition of the natural thing as that which bears the quiddity. In commentary XXXIV he adduces the following argument for this: the essence of a thing is a substance declaring the thing quiddatively; matter is not a substance declaring the quiddity of the thing; therefore matter does not belong to the essence of the thing. The minor is gathered from Physics I, text LXIX, where it is said that matter in itself is unknown, and consequently is not declarative of something else. From commentary XXI, moreover, the following argument can be elicited: if the quiddity of man were the composite man made of matter and form, then the quiddity of man would have a quiddity; and thus there would be a quiddity of a quiddity, which is false. The consequence holds, because whatever things are the same, whatever one has, the other also has: if, therefore, the quiddity of man and the composite man are the same, since the composite man has a quiddity, it follows that the quiddity of man has a quiddity. Aristotle seems to teach this same position in Metaphysics VII, text XXXIV, expressly saying that matter is not part of quiddity, and in Physics II, text XXXIII, placing the parts of a definition in the genus of formal cause. Hence also in Metaphysics X, text XXV, he says that male and female do not vary in species, because they are material differences. It may also be persuaded from the consequences of matter; for matter is the cause of corruption, of the distinction of supposit from nature, of sensibles, and of the like, whose opposites belong to quiddities: for the essences of things are ungenerated, incorruptible, insensible, and so forth. This concludes the first point.

CONCLUSION

Matter is part of the quiddity of a natural substance.

As to the second, St. Thomas, in Metaphysics VII at the cited text XXXIII, in the First Part, question LXXV, article 4, and here, holds that matter is part of the quiddity of a natural substance. He proves this conclusion with three arguments, two of which are placed in the text; the third is this: whatever belongs to the essence of all the individuals contained under a species, when universally conceived, belongs to the essence of the species. This is true because otherwise the specific essence would not be predicated essentially of the whole essence of the individual. But matter belongs to the essence of all natural individuals; therefore matter, universally taken, belongs to the essence of the species, and thus does not enter the species as that which bears it, but as an essential part. The opponents say concerning the first argument made in the text that it is proper to accidents to be defined by an addition of another genus; this does not belong to substances, but substances are defined by an addition of their own genus, for matter belongs to the genus in which the borne quiddity is. On the contrary: then there is no difference between the definition of the form of a part and the definition of the form of the whole, except perhaps according to the mode of signifying, since both are defined by an addition of their own genus; and thus the definition of soul and of the living thing will be the same. Then, just as no genus of the category of substance is placed in the definition of soul, so none will be placed in the definition of the living thing, and similarly with the others—which is manifestly false. St. Thomas’s position is further confirmed in three ways. First: in every object taken quiddatively to which some adequate property belongs, the cause of that property must be found intrinsically. But a body subject to contrariety, taken quiddatively, is a subject to which corruptibility belongs as an adequate property. Therefore, in a body subject to contrariety and taken quiddatively, the cause of corruptibility must be found intrinsically; and such a cause is none other than matter; therefore, and so forth. The major is self-evident, because a property flows from the intrinsic principles of the quiddity; otherwise it would not belong to it according to what it is. The minor is made clear by the fact that corruptibility is first concluded of a body subject to contrariety. That matter is the cause of corruptibility is especially clear according to the Commentator. Second: that which is part of human nature is part of human quiddity, because nature and quiddity are the same; but matter is part of human nature; therefore, and so forth. The minor is proved by the fact that matter is nature, Physics II, text XXI. And if it is not a part, then there must be in Socrates two non-partial natures, because they are not parts of any nature—which is impossible. Third, it is shown that this was Aristotle’s mind in Metaphysics I and VIII, texts XV and XVI, where he assigns the cause why the definition of composites is one: because from act and potency one thing naturally comes to be. Simple quiddities, he says, immediately possess unity through themselves, since they are forms alone. From this it follows that if the essence of a composite substance were form alone, Aristotle would not need to assign the reason why it is one: form is one through itself. But because it is composite, he therefore said that it has unity because one part is act and the other potency. Likewise, in Metaphysics IX, at the final text, he says that error occurs in the quiddities of composites, but not in those of simple things, because of the multitude of parts from which those quiddities are composed. Hence error can arise from their composition, whereas it has no place in simple things, since they lack parts. From this it is evident that he holds the essence of a composite to be composite and not simple, and that the quiddity of a material substance differs from a separate quiddity because the latter is essentially simple, while the former is essentially composite. This concludes the second point. As to the third, the opposing arguments must be answered. Concerning the first, the minor is denied: although matter in itself—that is, taken in isolation—is unknown, when joined to and underlying such a specific or generic form it is declarative of something else. Concerning the second, the consequence is denied. In proof of it, it is said that the major can be understood in two ways. In one way: whatever things are really the same, whatever is really joined to one is also really joined to the other; this is conceded, but it is not against us. In another way: whatever things are really the same, whatever is predicated of one is predicated of the other; in this way it is false. For something belongs to one insofar as it is conceptually distinct from the other, which does not belong to the other, as in the present case: to have a quiddity belongs to man insofar as he is conceptually distinct from his quiddity. For he is distinguished from it as the possessor from what is possessed. Since, therefore, the major must be distinguished in this way in the present case, the argument does not proceed. Concerning what is added from Aristotle, it is said that Metaphysics VII does not remove matter from quiddity, but removes particular matter and those parts which are accidental to the understanding of the species—hands and feet, for example—from the account of man: these flesh and these bones. That the parts of a definition are placed in the genus of formal cause is not contrary to what we say. For we must remember that every higher genus stands as formal with respect to the lower, as Aristotle establishes there. Male and female, although they do not differ in species in the genus of animal, as white and black do, nevertheless differ in species in the genus of sex; the differences of this genus are accidental to the genus of animal and arise from the side of matter, and therefore in that genus they do not cause specific diversity. Concerning the final confirmation from the properties of matter, it is said that those properties follow matter as it exists particularly, and do not follow matter abstracted from singulars, which is part of the specific quiddity. Therefore they need not be present in the quiddity, nor must matter be removed from quiddity because their opposites are present in the quiddity. But because the principle of individuation is matter, it may seem to follow that the essence which embraces matter and form together is merely particular and not universal; from this it would follow that universals have no definition, if essence is what is signified by a definition. In the third part of this chapter he objects against the fourth conclusion as follows: that which intrinsically comprehends matter in itself is particular; the essence of a composite substance intrinsically comprehends matter in itself; therefore the essence of substance is particular; therefore there is no universal essence of a composite substance—which is false. Further, it follows that natural universals are not definable, because among natural things only essences are definable, since a definition signifies the essence of a thing; but the essences of natural things, as has been established, are particular. The major is proved thus: that which has the principle of individuation intrinsically in itself in actuality is particular; that which intrinsically has matter has the principle of individuation in itself, because matter is the principle of individuation; therefore, and so forth. Accordingly, it must be known that matter is not the principle of individuation when taken in just any way, but only designated matter. I call designated matter that which is considered under determinate dimensions. This matter is not posited in the definition of man insofar as he is man, but would be posited in the definition of Socrates, if Socrates had a definition. In the definition of man, however, non-designated matter is posited: for this bone and this flesh are not posited in the definition of man, but bone and flesh absolutely, which are the non-designated matter of man.

Here he answers the objection by destroying the major together with its proof, saying that matter is taken in two ways: designated and non-designated. Designated matter is the principle of individuation; non-designated matter is posited as part of the specific essence. Designated matter would be posited in the definition of Socrates, if he were defined; non-designated matter is posited in the definition of universals. Hence it is clear that universals are defined and nevertheless include matter, but non-designated matter, which is the principle of particularity.