Lecture 12 — The corruptible and the incorruptible differ generically

But since contraries differ (or are other) specifically, and since corruptible and incorruptible are contraries (for privation is a definite incapacity), the corruptible and incorruptible must differ generically.

Now we have already spoken of these general terms. But, as will be seen, it is not necessary that every incorruptible thing should differ specifically from every corruptible thing, just as it is not necessary that a white thing should differ specifically from a black one.

For the same thing can be both at the same time if it is universal; for example, man can be both white and black. But the same thing cannot be both at the same time if it is a singular, for the same man cannot be both white and black at the same time, since white is contrary to black.

But while some contraries can belong to some things accidentally (for example, those just mentioned and many others), some cannot. Among these are the corruptible and the incorruptible. For nothing is corruptible accidentally. For what is accidental is capable of not belonging to a subject, but incorruptible is a necessary attribute of the things in which it is present. Otherwise, one and the same thing will be both corruptible and incorruptible, if it is possible for corruptibility not to belong to it.

The corruptible, then, must either be the substance or belong to the substance of each corruptible thing. The same also holds true for the incorruptible, for both belong necessarily to things. Hence, insofar as the one is corruptible and the other incorruptible, and especially on this ground, they are opposed to each other. Hence they must differ generically.

It is clearly impossible, then, that there should be separate forms, as some claim; for in that case, there would be one man who is corruptible and another who is incorruptible.

Yet the separate forms are said to be specifically the same as the individuals, and not in an equivocal sense, but things that differ generically are different to a greater degree than those that differ specifically.

2136. After having shown which contraries do not cause things to differ specifically, here the Philosopher explains which contraries cause things to differ generically. In regard to this, he does three things.

First (1058b26; [2136]), he establishes the truth.

Second (1058b29; [2138]), he rejects the false opinion of certain men, at now we have already.

Third (1059a10; [2143]), he draws a corollary from his discussion, at it is clearly.

He accordingly first of all (1058b26) lays down two premises necessary for the proof of his thesis.

The first of these is that contraries are formally different, as was explained above (1058a8; [2120]).

Corruptible and incorruptible are generically different

2137. The second premise is that the corruptible and the incorruptible are contraries. He proves this from the fact that the incapacity opposed to a definite capacity is a kind of privation, as has been stated in book 9 [1784]. Now privation is a principle of contrariety; therefore, it follows that incapacity is contrary to capacity, and that the corruptible and the incorruptible are opposed as capacity and incapacity. But they are opposed in a different way. For if “capacity” is taken according to its general meaning, as referring to the ability to act or to be acted upon in some way, then the term “corruptible” is used like the term “capacity,” and the term “incorruptible” like the term “incapacity.” But if the term “capacity” is used of something inasmuch as it is incapable of undergoing something for the worse, then contrariwise, the term “incorruptible” is referred to “capacity,” and the term “corruptible” is referred to “incapacity.”

But although it seems necessary from these remarks to conclude that the corruptible and the incorruptible differ specifically, he concludes that they differ generically. And this is true, for just as form and act pertain to the species, so too matter and capacity pertain to the genus. Hence, just as the contrariety which pertains to form and act causes difference in species, so too the contrariety which pertains to capacity or potency causes difference in genus.

2138. Now we have already (1058b29). Here he rejects the false opinion of certain men, and in regard to this, he does two things.

First, he gives this opinion.

Second (1058b35; [2139]), he shows that it is false, at but while some.

He accordingly first says (1058b29) that the proof which was given above regarding the corruptible and the incorruptible is based on the meaning of these universal terms, that is, inasmuch as one signifies a capacity and the other an incapacity.

But, as it seems to certain men, it is not necessary that the corruptible and the incorruptible should differ specifically, just as this is not necessary for white and black, because it is admissible for the same thing to be both white and black, although in different ways. For if what is said to be white and black is something universal, it is white and black at the same time in different subjects. Thus it is true to say that man is at the same time both white, because of Socrates, and black, because of Plato. But if it is a singular thing, it will not be both white and black at the same time (although it can now be white and afterward black), since white and black are contraries. Thus some say that some things can be corruptible and some incorruptible within the same genus, and that the same singular thing can sometimes be corruptible and sometimes incorruptible.

2139. But while some (1058b35). Here he rejects the foregoing opinion. He says that some contraries belong accidentally to the things of which they are predicated, as white and black belong to man, as has been mentioned already (1058a36; [2131]). And there are many other contraries of this kind in reference to which the view stated is verified, namely, that contraries can exist simultaneously in the same species and successively in the same singular thing. But there are other contraries which are incapable of this, and among these are the corruptible and the incorruptible.

2140. For corruptible does not belong accidentally to any of the things of which it is predicated, because what is accidental is capable of not belonging to a thing. But corruptible belongs necessarily to the things in which it is present. If this were not so, it would follow that the very same thing would sometimes be corruptible and sometimes incorruptible; but this is naturally impossible. (However, this does not prevent the divine power from being able to keep some things that are corruptible by their very nature from being corrupted.)

2141. Since the term “corruptible,” then, is not an accidental predicate, it must signify either the substance of the thing of which it is predicated or something belonging to the substance, for each thing is corruptible by reason of its matter, which belongs to its substance. The same argument applies to incorruptibility, because both belong to a thing necessarily. Hence it is evident that corruptible and incorruptible are opposed as essential predicates, which are predicated of a thing inasmuch as it is a thing of this kind, as such, and primarily.

2142. And from this it necessarily follows that the corruptible and the incorruptible differ generically, for it is evident that contraries which belong to one genus do not belong to the substance of that genus—for rational and irrational do not belong to the substance of animal. But animal is the one or the other potentially. And whatever genus may be taken, corruptible and incorruptible must pertain to its intelligible make-up. It is impossible, then, that they should have a common genus. And this is reasonable, for there cannot be a single matter for both corruptible and incorruptible things. Now, speaking from the viewpoint of the philosophy of nature, genus is taken from the matter; thus, it was said above (1058a21; [2125]) that things that do not have a common matter are other or different in genus. But speaking from the viewpoint of logic, nothing prevents them from having the same common genus inasmuch as they have one common definition, either that of substance, or of quality, or of quantity, or something of this sort.

2143. It is clearly impossible (1059a10). Next he draws a corollary from his discussion, namely, that there cannot be separate forms, as the Platonists claimed. For they maintained that there are two men: a sensible man who is corruptible, and a separate man who is incorruptible, which they called the separate form or idea of man. But the separate forms or ideas are said to be specifically the same as individual things, according to the Platonists. And the name of the species is not predicated equivocally of the separate form and of singular things, although the corruptible and the incorruptible differ even generically. And those things that differ generically are different to a greater degree than those that differ specifically.

2144. Now it must be observed that, although the Philosopher has shown that some contraries do not cause things to differ specifically, and that some cause things to differ even generically, nevertheless, all contraries cause things to differ specifically in some way if the comparison between contraries is made with reference to some definite genus. For even though white and black do not cause difference in species within the same genus of animal, they do cause difference in species in the genus of color. And male and female cause difference in species in the genus of sex. And while living and non-living cause difference in genus in reference to the lowest species, still, in reference to the genus which is divided per se into living and non-living, they merely cause difference in species. For all differences of a genus constitute certain species, although these species can differ generically.

2145. But corruptible and incorruptible divide being per se, because that is corruptible which is capable of not being, and that is incorruptible which is incapable of not being. Hence, since being is not a genus, it is not surprising if the corruptible and the incorruptible do not have a common genus. This brings our treatment of book 10 to a close.