A critical history of Greek philosophy

by W. T. Stace

Aristotle's metaphysical theory grows naturally out of his polemic against Plato's theory of Ideas, because his own system was in effect simply an attempt to overcome the defects which he found in Plato. The main heads of this polemic are the following:--

(1) Plato's Ideas do not explain the existence of things. To explain why the world is here is after all the main problem of philosophy, and Plato's theory fails to do this. Even admitting that, say, the Idea of whiteness exists, we cannot see how it produces white objects.

(2) Plato has not explained the relation of Ideas to things. Things, we are told, are "copies" of Ideas, and "participate" in them. But how are we to understand this "participation"? In using such phrases, says Aristotle, Plato is giving no real account of the relationship, but is merely "uttering poetic metaphors."

(3) Even if the existence of things is explained by the Ideas, their motion is not. Suppose that the Idea of whiteness produces white things, the Idea of beauty beautiful things, and so on, yet, since the Ideas themselves are immutable and motionless, so will be the world which is their copy. Thus the universe would be [{263}] absolutely static, like Coleridge's "painted ship upon a painted ocean." But the world, on the contrary, is a world of change, motion, life, becoming. Plato makes no attempt to explain the unceasing becoming of things. Even if the Idea of whiteness explains white objects, yet why do these objects arise, develop, decay, and cease to exist? To explain this there must be some principle of motion in the Ideas themselves. But there is not. They are immovable and lifeless.

(4) The world consists of a multitude of things, and it is the business of philosophy to explain why they exist. By way of explanation Plato merely assumes the existence of another multitude of things, the Ideas. But the only effect of this is to double the number of things to be explained. How does it help thus to duplicate everything? And Aristotle likens Plato to a man who, being unable to count with a small number, fancies that, if he doubles the number, he will find it easier to count.

(5) The Ideas are supposed to be non-sensuous, but they are, in fact, sensuous. Plato thought that a non-sensuous principle must be sought in order to explain the world of sense. But not being able to find any such principle, he merely took the objects of sense over again and called them non-sensuous. But there is, in fact, no difference between the horse and the Idea of the horse, between the man and the Idea of the man, except a useless and meaningless "in-itself" or "in-general" attached to each object of sense to make it appear something different. The Ideas are nothing but hypostatized things of sense, and Aristotle likens them to the anthropomorphic gods of the popular religion. "As [{264}] these," he says, "are nothing but deified men, so the Ideas are nothing but eternalized things of nature." Things are said to be copies of Ideas, but in fact the Ideas are only copies of things.

(6) Next comes the argument of the "third man," so called by Aristotle from the illustration by which he explained it. Ideas are assumed in order to explain what is common to many objects. Wherever there is a common element there must be an Idea. Thus there is a common element in all men, and therefore there is an Idea of man. But there is also an element common to the individual man and to the Idea of man. There must, therefore, be a further Idea, the "third man," to explain this. And between this further Idea and the individual man there must be yet another Idea to explain what they have in common, and so on ad infinitum.

(7) But by far the most important of all Aristotle's objections to the ideal theory, and that which, to all intents and purposes, sums up all the others, is that it assumes that Ideas are the essences of things, and yet places those essences outside the things themselves. The essence of a thing must be in it, and not outside it. But Plato separated Ideas from things, and placed the Ideas away somewhere in a mysterious world of their own. The Idea, as the universal, can only exist in the particular. Possibly the reality in all horses is the universal horse, but the universal horse is not something that exists by itself and independently of individual horses. Hence Plato was led into the absurdity of talking as if, besides the individual horses we know, there is somewhere another individual called the horse-in-general, or as if besides white objects there is a thing called [{265}] whiteness. And this is in fact the supreme self-contradiction of the theory of Ideas, that it begins by saying that the universal is real, and the particular unreal, but ends by degrading the universal again into a particular. This is the same thing as saying that Plato's mistake lay in first (rightly) seeing that existence is not reality, but then (wrongly) going on to imagine that the reality is an existence.

Out of this last objection grows Aristotle's own philosophy, the fundamental principle of which is that the universal is indeed the absolute reality, but that it is a universal which exists only in the particular. What is reality? What is substance? This is the first question for the metaphysician. Now substance is what has an independent existence of its own; it is that whose being does not flow into it from any source outside itself. Consequently, substance is what is never a predicate; it is that to which all predicates are applied. Thus in the proposition, "Gold is heavy," gold is the subject, or substance, and "heavy" is its predicate. The heaviness is dependent for its existence on the gold, and it is therefore the latter, and not the former, that is the substance.

Now, keeping this in mind, are universals, as Plato asserts, substances? No; because the universal is merely a common predicate which attaches to many objects of a class. Thus the concept of man is merely what is common to all men. It is the same thing as the predicate "humanness." But humanness cannot exist apart from human beings, any more than heaviness apart from the heavy object. Universals, then, are not substances. But neither are particulars substances. For there is no such thing as that which is absolutely [{266}] particular and isolated. If humanness does not exist apart from men, neither do men exist apart from humanness. Take away from a man what he has in common with other men, and what he has in common with other objects, and you will find that, having stripped him of all his qualities, there is absolutely nothing left. We say gold is heavy, yellow, malleable, etc. Now the heaviness, the yellowness, and the other qualities, cannot exist apart from the gold. But it is equally true that the gold cannot exist apart from its qualities. Strip off all its qualities in thought, and then ask yourself what the gold itself is apart from its qualities. You will find that your mind is a total blank. In taking away the qualities you have taken away the gold itself. The gold can only be thought through its qualities. It only exists through its qualities. The gold, therefore, just as much depends on the qualities for its existence as the qualities depend upon the gold. Hence neither of them, considered apart from the other, is substance. But the qualities are the universal element in the gold, the gold without the qualities is the absolutely particular and isolated. For, first, the yellowness is a quality which this gold has in common with that gold, and is therefore a universal, and so with all the qualities. Even if a particular piece of gold has a quality possessed by no other gold, it is yet possessed by some other object in the universe, or it would be unknowable. Every quality is consequently a universal. Secondly, the gold without its qualities is the absolutely particular. For, being stripped of all qualities, it is stripped of whatever it has in common with other things; it is stripped of whatever universality it has, and it remains an absolute particular. Hence the [{267}] universal is not substance, nor is the particular. For neither of them can exist without the other. Substance must be a compound of the two; it must be the universal in the particular. And this means that that alone which is substance is the individual object, for example, the gold with all its qualities attached to it.