Commentary Aristotle Metaphysics
434. Further, those things. Then he gives the second argument, which runs thus. If genera are called principles because they are common and predicated of many things, then for a like reason all those things that are principles because they are common and predicated of many will have to be genera. But all things that are intermediate between the first genera and individuals (namely, those which are considered together with some differences) are common predicates of many things. Hence they are both principles and genera. But this is evidently false. For some of them are genera, like subaltern species, whereas others are not, as the lowest species. It is not true, then, that the first or common genera are the principles of things.
435. Further, if the first genera are principles, because they are the principles by which we know species, then differences will be principles to a greater degree, because differences are the formal principles of species, and form or act is chiefly the principle of knowing. But it is unfitting that differences should be the principles of things, because in that case there would be an infinite number of principles, so to speak. For the differences of things are infinite, in a way—not infinite in reality but to us. That they are infinite in number is revealed in two ways: in one way if we consider the multitude of differences in themselves; in another way if we consider the first genus as a first principle, for evidently innumerable differences are contained under it. The first genera, then, are not the principles of things.
436. But, on the other hand. Then he shows that the lowest species are principles to a greater degree than genera. He gives three arguments, of which the first runs thus.
According to the Platonists it is the one which seems to have the species, or character, of a principle to the greatest degree. Indeed, unity has the character of indivisibility, because a one is merely an undivided being. But a thing is indivisible in two ways, namely, in quantity and in species. In quantity, as the point and unit, and this is a sort of indivisibility opposed to the division of quantity; in species, as what is not divided into many species. But of these two types of indivisibility the first and more important one is indivisibility in species, just as the species of a thing is prior to its quantity. Therefore, that which is indivisible in species is more of a principle because it is indivisible in quantity. And in the division of quantity the genus seems to be more indivisible, because there is one genus of many species, but in the division of species one species is more indivisible. Hence the last term which is predicated of many which is not a genus of many species (namely, the lowest species) is one to a greater degree in species than a genus—for example, man or any other lowest species is not the genus of particular men. Therefore, a species is a principle to a greater degree than a genus.
437. Further, in the case. Then he gives the second argument, which is based on a certain position of Plato.
At one time Plato held that there is some one thing which is predicated of many things without priority and posteriority, and that this is a separate unity, as man is separate from all men. At another time he held that there is some one thing which is predicated of many things according to priority and posteriority, and that this is not a separate unity.
This is what Aristotle means when he says in the case of those things to which prior and subsequent apply—in other words, when one of the things of which a common term is predicated is prior to another, it is impossible in such cases that there should be anything separate from the many things of which this common term is predicated.
For example, if numbers stand in such a sequence that two is the first species of number, no separate idea of number will be found to exist apart from all species of numbers. And on the same grounds no separate figure will be found to exist apart from all species of figures.
438. The reason for this can be that a common attribute is held to be separate so as to be some first entity in which all other things participate. If, then, this first entity is a one applicable to many in which all other things participate, it is not necessary to hold that there is some separate entity in which all things participate. But all genera seem to be things of this kind, because all types of genera are found to differ insofar as they are more or less perfect, and thus insofar as they are prior and subsequent in nature.
Hence, if in those cases in which one thing is prior to another, it is impossible to regard anything common as a separate entity on the supposition that there is a genus apart from species, then in the case of other things the teaching will differ—there will be another doctrine and rule concerning them, and the foregoing rule will not apply to them.
But considering the individuals of one species, it is evident that one of these is not prior and another subsequent in nature, but only in time. And thus according to Plato’s teaching a species is separate. Since, then, these common things are principles inasmuch as they are separate, it follows that a species is a principle to a greater degree than a genus.
439. Further, where one thing. Here he gives the third argument, which uses the notions “better or worse.” For in all those cases where one thing is better than another, that which is better is always prior in nature. But there cannot be held to be one common genus of those things that exist in this way. Hence there cannot be held to be one separate genus in the case of those things in which one is better and another worse. Thus the conclusion is the same as the above. For this argument is introduced to strengthen the preceding one, so to speak, with a view to showing that there is priority and posteriority among the species of any genus.
440. And from these three arguments he draws the conclusion in which he is chiefly interested: the lowest species, which are predicated immediately of individuals, seem to be the principles of things to a greater degree than genera. Here he uses the genitive case in the place of the ablative, as is the Greek custom. Thus Boethius’ rendition is more clear, which expressly concludes that lowest species are more principles than genera.
441. But again it is not. Here he argues the opposite side of the question as follows. A principle and a cause are distinct from the things of which they are the principle and cause, and are capable of existing apart from them. And this is true, because nothing is its own cause. He is speaking here of extrinsic principles and causes, which are causes of a thing in its entirety. But the only thing that is held to exist apart from singular things is what is commonly and universally predicated of all things. Therefore, the more universal a thing is, the more separate it is, and the more it should be held to be a principle. But the first genera are most universal. Therefore, the first genera are the principles of things in the highest degree.
442. Now the solution to these questions is implied in this last argument. For, according to this argument, genera or species are held to be universal principles inasmuch as they are held to be separate. But the fact that they are not separate and self-subsistent is shown in book 7 of this work. Hence the Commentator also shows, in book 8, that the principles of things are matter and form, to which genus and species bear some likeness. For a genus is derived from matter and difference from form, as will be shown in the same book.
Hence, since form is more of a principle than matter, species will consequently be principles more than genera. But the objection which is raised against this, on the grounds that genera are the principles of knowing a species and its definitions, is answered in the same way as the objection raised about their separateness. For, since a genus is understood separately by the mind without understanding its species, it is a principle of knowing. And in the same way it would be a principle of being, supposing that it had a separate being.