LESSON 10

How Contraries Differ in Species

  Chapter 8: 1057b 35-1058a 28

             887. That which is differentiated specifically differs from something, and it must be in both of the things which differ; for example, if animal is differentiated into species, both must be animals (840). Hence those things which differ specifically must belong to the same genus; for by genus I mean that by which both things are said to be one and the same, and which does not involve an accidental difference, whether it is conceived as matter or in some other way. For not only must the common attribute belong to both, for example, that both are animals, but animal itself must also be different in such things; for example, the one must be a horse and the other a man. This common attribute, then, must be specifically different in each. Therefore the one will be essentially this kind of animal and the other that kind of animal; for example, the one will be a horse and the other a man. Thus it is necessary that this difference be a difference of the genus; for by a difference of a genus I mean the difference which makes the genus itself different.

             888. Therefore this will be contrariety; and this also becomes clear by an induction; for all things are distinguished by opposites.

             889. And it has been shown (843) that contraries belong to the same genus; for contrariety was shown to be the perfect difference (844). And every difference in species is something of something. Hence this is the same for both and is their genus. Thus all contraries which differ specifically and not generically are contained in the same order of the categories (841), and they differ from each other to the greatest degree; for the difference between them is a perfect one, and they cannot be generated at the same time. The difference, then, is contrariety; for this is what it means to differ specifically, namely, to have contrariety and to belong to the same genus while being undivided. And all those things are specifically the same which do not have contrariety while being undivided; for contrarieties arise in the process of division and in the intermediate cases before one reaches the things which are undivided.

             890. It is evident, then, regarding what is called the genus, that none of the things which agree in being species of the same genus are either specifically the same as the genus or specifically different from it; for matter is made known by negation, and the genus is the matter [of that of which it is considered to be the genus]; not in the sense that we speak of the genus (or race) of the Heraclidae, but in the sense that genus is found in a nature (524); nor is it so with reference to things that do not belong to the same genus; but they differ from them in genus, and things that differ specifically differ from those that belong to the same genus. For a contrariety must be a difference, but it need not itself differ specifically. To differ specifically, however, pertains only to things that belong to the same genus.

COMMENTARY

             2112. Because the Philosopher has shown above (840:C 2107) that contrariety is a kind of difference, and difference is either generic or specific, his aim here is to show how contraries differ generically and specifically. This is divided into two parts. In the first (887:C 2112) he shows that difference in species is contrariety. In the second (891:C 2127) he shows how this does not apply in the case of some contraries ("But someone").

             In regard to the first he does three things. First, he shows that the difference which causes difference in species belongs essentially to the same genus as the attribute which divided the nature itself of the genus into different species. Second (888:C 2120), he shows that this is proper to contrariety ("Therefore this will"). Third (890:C 2124), he draws a corollary from what has been said ("It is evident").

             He accordingly says, first (887), that wherever there is difference in species two things must be considered, namely, that one thing differs from something else, and that there is something which is differentiated by these two. And that which is differentiated by these two must belong to both; for example, animal is something divided into various species, say, man and horse; and both of these, man and horse, must be animals. It is evident, then, that things which differ specifically from each other must belong to the same genus.

             2113. For that which is one and the same for both and is not predicated of each accidentally or differentiated into each accidentally is called their genus. Hence it must have a difference which is not accidental whether the genus is assumed to have the nature of matter or is taken in some other way.

             2114. Now he says this because matter is differentiated in one way by form, and genus is differentiated in another way by differences; for form is not matter itself but enters into composition with it. Hence matter is not the composite itself but is something belonging to it. But a difference is added to a genus, not as part to part, but as whole to whole; so that the genus is the very thing which is the species, and is not merely something belonging to it. But if it were a part, it would not be predicated of it.

             2115. Yet since a whole can be named from one of its own parts alone, for example, if a man is said to be headed or handed, it is possible for the composite itself to be named from its matter and form. And the name which any whole gets from its material principle is that of the genus. But the name which it gets from its formal principle is the name of the difference. For example, man is called an animal because of his sensory nature, and he is called rational because of his intellective nature. Therefore, just as "handed" belongs to the whole even though the hand is a part, in a similar way genus and difference refer to the whole even though they are derived from the parts of the thing.

             2116. If in the case of genus and difference, then, one considers the principle from which each is derived, the genus is related to differences as matter is to forms. But if one considers them from the viewpoint of their designating the whole, then they are related in a different way. Yet this is common to both, namely, that just as the essence of matter is divided by forms, so too the nature of a genus is divided by differences. But both differ in this respect, that, while matter is contained in both of the things divided, it is not both of them. However, the genus is both of them; because matter designates a part, but the genus designates the whole.

             2117. Therefore in explaining his statement that a genus is that by which both of the things which differ specifically are said to be one and the same, he adds that, not only must the genus be common to both of the things which differ specifically (as, for instance, both are animals) as something which is undivided is common to different things, just as a house and a possession are the same, but the animal in both must differ, so that this animal is a horse and that animal is a man.

             2118. He says this against the Platonists, who claimed that there are common separate natures in the sense that the common nature would not be diversified if the nature of the species were something else besides the nature of the genus. Hence from what has been said he concludes against this position that whatever is common is differentiated specifically. Hence the common nature in itself, for example, animal, must be this sort of animal with one difference, and that sort of animal with another difference, so that the one is a horse and the other is a man. Thus if animal in itself is this and that sort of animal, it follows that the difference which causes difference in species is a certain difference of the genus. And he explains the diversification of a genus which makes a difference in the generic nature itself.

             2119. Now what the Philosopher says here rules out not only the opinion of Plato, who claimed that one and the same common nature exists of itself, but also the opinion of those who say that whatever pertains to the nature of the genus does not differ specifically in different species, for example, the opinion that the sensory soul of a man does not differ specifically from that in a horse.

             2120. Therefore this will (888).

             Then he shows that the difference which divides the genus essentially in the foregoing way is contrariety. He says that, since the specific difference divides the genus essentially, it is evident that this difference is contrariety.

             He makes this clear, first, by an induction; for we see that all genera are divided by opposites. And this must be so; for those things which are not opposites can coexist in the same subject; and things of this kind cannot be different, since they are not necessarily in different things. Hence anything common must be divided by opposites alone.

             2121. But the division of a genus into different species cannot come about by way of the other kinds of opposites. For things which are opposed as contradictories do not belong to the same genus, since negation posits nothing. The same is true of privative opposites, for privation is nothing else than negation in a subject. And relative terms, as has been explained above (881:C 2103), belong to the same genus only if they are in themselves relative to each other and are in a sense contraries, as has been stated above (ibid.). It is evident, then, that only contraries cause things belonging to the same genus to differ specifically.

             2122. And it has (889).

             Then he proves the same point by an argument. He says that contraries belong to the same genus, as has been shown (883:C 2105). For it has been pointed out (844:C 2027-29) that contrariety is the perfect difference; and it has also been stated (889) that difference in species is "something of something," i.e., from something. And besides this it has been noted (887:C 2112) that the same genus must belong to both of the things which differ specifically. Now from these two considerations it follows that all contraries are contained in the same "order of the categories," i.e., in the same classification of predicates, yet in such a way that this is understood of all contraries which differ specifically but not generically. He says this in order to preclude the corruptible and the incorruptible, which are later said to differ generically.

             2123. And contraries not only belong to one genus but they also differ from each other. This is evident, for things which differ perfectly as contraries are not generated from each other at the same time. Therefore, since difference in species requires identity of genus and the division of the genus into different species, and since both of these are found in contrariety, it follows that difference in species is contrariety. This is evident because in order for things in the same genus to differ specifically they must have contrariety of differences "while being undivided," i.e., when they are not further divided into species, as the lowest species. And these are said to be undivided inasmuch as they are not further divided formally. But particular things are said to be undivided inasmuch as they are not further divided either formally or materially. And just as those things are specifically different which have contrariety, so too those things are specifically the same which do not have contrariety, since they are not divided by any formal difference. For contrarieties arise in the process of division, not only in the highest genera but also in the intermediate ones, "before one reaches the things which are undivided," i.e., the lowest species. It is accordingly evident that, even though there is not contrariety of species in every genus, there is contrariety of differences in every genus.

             2124. It is evident (890).

             Here he draws a corollary from what has been said, namely, that none of the things which agree in being species of the same genus are said to be either specifically the same as the genus or specifically different from it; for things which are said to be specifically the same have one and the same difference, whereas things which are said to be specifically different have opposite differences. Hence, if any species is said to be specifically the same as the genus or specifically different from it, it follows that the genus will contain some difference in its definition. But this is false.

             2125. This is made evident as follows: matter "is made known by negation," i.e., the nature of matter is understood by negating all forms. And in a sense genus is matter, as has been explained (887:C 2113-15); and we are now speaking of genus in the sense that it is found in the natures of things, and not in the sense that it applies to men, as the genus (or race) of the Romans or of the Heraclidae. Hence it is clear that a genus does not have a difference in its definition.

             2126. Thus it is evident that no species is specifically different from its genus, nor is it specifically the same as its genus. And similarly things that do not belong to the same genus do not differ specifically from each other, properly speaking, but they do differ generically. And things that differ specifically differ from those that belong to the same genus; for a contrariety is the difference by which things differ specifically, as has been explained (888:C 2120)--not that the contrariety itself of the differences need differ specifically, even though contraries differ specifically; but contrariety is found only in those things that belong to the same genus. It follows, then, that to differ specifically does not properly pertain to things that belong to different genera.