Luke Morris

12/05/2003

Aristotle vs. Plato – An Ongoing Battle

The notion of universals poses one of the greatest problems to philosophy, provoking questions in ethics and metaphysics over which thinkers still debate today. Do things have essences or natures that make them what they are? What could such natures tell us about the things themselves? If a thing has a nature, where might we find it? Do non-physical things such as moral standards actually exist? If so, where do they exist, and how would we define them?

These questions have remained unsolved since Plato and Aristotle first started the controversy over them. So let us examine how the Greeks seek to solve the puzzle. Plato, for one, formulates his answer by postulating the existence of “Forms,” or essential natures, that exist apart from and above those things that bear their names in the physical world. The Forms are non-physical, eternal, unmoving, unchanging “Ideas” that exist in the divine realm, and in which things of this world may participate to a greater or lesser extent. Aristotle, likewise, agrees with Plato that things have natures that make them what they are, but he denies that such natures could exist apart from the things themselves. On this point Aristotle is completely correct. We cannot search for the nature of morality, for instance, outside of the beings that possess morality, since this would give us no means to discover what the nature of morality is. We must instead discover our universals, not in some supernatural realm outside of possible human experience, but within the real world in which we live our lives.

A universal, by Aristotle’s description, involves a nature or quality that we apply to two or more primary, or individual, substances (Categories 1b25). Aristotle presents this notion of universals, for instance, through the relationship of art to experience, “when from many notions gained by experience one universal judgment about similar objects is produced” (Metaphysics 981a5). Universals, therefore, allow us to categorize individual things or substances according to their similarities with others. Hence, when we describe a certain man as just, we apply to him the universal of justice, which may exist in a similar form in other men. Such a concept, however, only works when applied to those individual things, or primary substances, that possess it, since “if the primary substances did not exist it would be impossible for any of the other things to exist” (Categories 2b5). We cannot classify man as a species, for instance, if no men exist to place into that category, and the same holds true for universals, particularly in the fact that only a substance can receive “contraries” – i.e. a man can be at different times bad or good (Categories 4b16), and these contraries of nature we call universals. We could not say, in addition, that such universals as “bad” or “good” exist, if we had no particulars to which we could apply them.

While Plato does not hold to Aristotle’s concept of universals, he attempts to use the Forms to fulfill the same duties. “Justice and injustice,” he writes, “good and bad, and all the essential Forms: each in itself is one; but they manifest themselves in a great variety of combinations, with actions, with material things, and with one another, and so each seems to be many” (Republic 476a). Plato claims that a Form exists when we see two or more things that possess a similar trait that we call by the same name. A beautiful woman and a beautiful horse, for instance, would both share or “participate” in the Form of Beauty. (By this principle the woman might, in addition, share in the Form of “womanness” with others of her sex, as the horse participates in the Form of “horseness,” which thus enables the Forms to fulfill the role of Aristotle’s “Secondary substances.” This, however, lies outside the basic consideration of universals in moral notions.) “Corresponding to each of these sets of many things,” Plato says, “we postulate a single Form or real essence, as we call it . . . Further, the many things, we say, can be seen, but are not objects of rational thought; whereas the Forms are objects of thought, but invisible” (507b). The Forms, therefore, exist outside of the material world, apart from the things that share in them here on Earth. But if the Forms do not exist in the particulars to which we attribute them, how do they apply to things in this world? How could values, such as beauty, have an objective existence over and above what is valuable or beautiful?

Plato’s student Aristotle, we see, becomes the harshest critic of his teacher’s “transcendent” values. One of Aristotle’s criticisms of Plato’s theory states that the Forms do not do anything here on Earth. Even if they did exist, what good would it do us to talk about them, since by their very definition the Forms cannot cause anything? Aristotle wonders, rightly,

What on Earth the Forms contribute to sensible things, either to those that are eternal or to those that come into being and cease to be. For they cause neither movement nor any change in them. But again they help in no way towards the knowledge of the other things . . . nor towards their being, if they are not in the particulars which share in them. (Metaphysics 991a 9-14)

The natures of things result from their causes, and these causes cover four types: the material, the formal, the efficient, and the final, or teleological, cause. Aristotle attacks the theory of Forms for not taking all of these causes into account for the natures of things, and particularly for not dealing with efficient causation; that is, for not telling us how things may be generated, moved, changed, or destroyed.

On this last point, Plato might try to defend himself by claiming that he never meant for the Forms to serve as efficient causes. He would argue, rather, “that the greater is greater by size, and that size is the cause of its being greater” (Phaedo 101a); in other words, he uses Forms merely as formal causes, not as efficient ones. Indeed, Aristotle himself admits that Plato uses “cause” in only two senses, “that of the essence and the material cause” (Metaphysics 988a9). (Though Plato seems to use the “essence” in this case to cover both the formal and the final cause, or purpose, of a thing). Plato adds, “You know of no way in which a thing can be generated, except by participation in its own proper essence” (Phaedo 101c). But does not the act of generation imply efficient cause? Yet the Forms, by definition, cannot move or change; therefore, they cannot cause movement or change in physical things; how then could they generate anything? As Aristotle interprets Plato, the problem is that, “The Forms are causes both of being and of becoming; yet when the Forms exist, still the things that share in them do not come into being, unless there is some efficient cause” (Metaphysics 991b 4-5). We have, hence, a contradiction by definition. A Form that cannot move cannot serve as an efficient cause, yet it is supposed to provide the cause of a thing’s coming into being. By what principle, then, can an object’s “participation” in a Form provide the efficient cause for that object’s existence?

The problem with Plato’s thought, Aristotle shows, is that when you remove the form of a thing from the thing itself, you leave the relationship between the form and the thing an open mystery. As Aristotle sees them, “The Forms are practically equal to or not fewer than the things . . . For to each set of substances there answers a Form which has the same name and exists apart from the substances, and so also in the case of all other groups in which there is one character common to many things” (Metaphysics 990b 4-8). So, how can we know what the Forms are supposed to be, if we do not know how they connect with things in our world? Plato might answer that the Forms are “patterns” in which things share or participate. But “to say that they [Forms] are patterns and the other things share them is to use empty words and poetical metaphors” (Metaphysics 991a 21-22), for we cannot point to anything as the nature of such patterns, or to the way in which things are supposed to “participate” in them. In describing the nature of beauty, for instance, Plato (through the character of Socrates) asserts, “The thing is only made beautiful by the presence or communication, or whatever you please to call it, of absolute beauty;” but he goes on to declare that, “I do not wish to insist on the nature of the communication” (Phaedo 100d). Plato, indeed, never does give us a description of the way in which things are supposed to communicate with, or participate in, the Forms, nor does he give us a complete logos of what the Forms really are.

If we posit the Forms, which fail to include efficient causes, as the natures of things, we cannot possibly determine what purpose they would serve, and we end up running our thoughts in a circle. For Plato says, “If anything besides absolute beauty is beautiful, it is so simply because it partakes of absolute beauty, and I say the same of all phenomena” (Phaedo 100c). What, then, makes a thing beautiful? Its participation in absolute Beauty does. What is absolute Beauty? It is that in which beautiful things participate. Obviously then we cannot describe the Forms using sensory predicates. The only way to escape this circle is to claim, as Aristotle does, that “The Forms will be substance; and the same terms indicate substance in this and in the ideal world” (Metaphysics 990b32-991a1). Thus, we describe beauty here and Beauty in the Ideal world by the same terms, and we need not add any further definition. But if we use the same descriptive terms and give them the same meaning for both the thing that is beautiful and for beauty itself – if, that is, we posit a relation of similarity between the two – then we must posit a Form for this commonality as well. “And if the Ideas and the particulars that share them have the same Form,” Aristotle claims, “there will be something common to these” (991a 3-4). Hence, by trying to escape a circular definition, we run into an infinite regress, or the “third man” argument.

In addition to these logical flaws in Plato’s theory, Aristotle also points out the absurdity of placing “substance” in general above substances in particular. The Form of a moral notion, according to Plato, is eternal, and things that come into existence come to participate in it to some extent. Therefore, Aristotle claims, “The arguments for the Forms destroy the things for whose existence we are more anxious than for the existence of the Ideas; for it follows not that the dyad [the particular pair] but number [the category into which it falls] is first, i.e. that the relative is prior to the absolute” (Metaphysics 990b 18-20). In other words, we would rather know that such a thing as “2” exists than that such a thing as “number” in general exists. Hence, “A thing-as-such, i.e., a substance, is by nature prior to a relation into which it can enter” (Ethics 1096a20). Moral notions that we apply to men, such as justice, wisdom, and piety, all apply to a man’s relation to his own actions, and therefore presuppose that a man must exist to exhibit such universals, before the universals themselves can exist.

Aristotle argues, in opposition to Plato, that a thing’s essential nature must be present in the thing itself. If we wish to describe the universal principle of justice, for instance, we cannot assume that justice could exist if there were no just people to represent it. “It must be held impossible that the substance and that of which it is the substance should exist apart,” Aristotle writes, “how, therefore, can the Ideas, being the substances of things, exist apart?” (Metaphysics 991b 1-3). The substance of a thing must include all of the four causes that compose it – the matter; its form or shape; the maker who causes it to come into being; and the final purpose or telos for the sake of which it exists (Physics 198a23) – and these causes make up the thing’s essential nature, what it truly is to be that thing. As Aristotle says, “nature is a cause, a cause that operates for a purpose” (Physics 199b32). If the nature of a thing is not within the thing itself, though, it cannot truly act as a cause in any of the above senses, since as an unmoving, external Form it would not provide the generation, the material, or even the form of the thing itself, or the purpose for which that thing might exist.

Since they do not provide an explanation for nature as a cause, in the wider, all encompassing sense in which Aristotle means, the Forms can contribute nothing to our understanding of things. While Plato might claim that “The Form or essential nature of Goodness . . . is the cause of knowledge and truth” (Republic 508e), he does not show how this cause might connect to our knowledge of the world, or in what sense it can be a cause of anything that exists here. By positing a disconnection between our everyday reality and its meaning, Plato removes from us any access we may have to universal standards of the type that could apply to us. The Form or essence of a set of many like things is itself singular (Republic 507b). But if it is only one, and it does not exist within the many things, how can we say that a particular person could ever possess such a thing as goodness? (Plato, of course, would argue that he does not possess it, but that he “participates” in it, though this still leaves the issue unresolved.) As Aristotle states, “The good cannot be something universal, common to all cases, and single; for if it were, it would not be applicable in all categories but only in one” (Ethics 1096a 28-29). If two different men, therefore, act equally according to what is “good” in completely different situations, only one of them could be said to be participating in the Form of “goodness,” since goodness would only apply to that situation.

While Plato and Aristotle both believe in the existence of universal standards of such things as beauty, justice, and the good, only Aristotle presents a rational theory that we can apply to our real-world experience. Plato’s mystical dualism, by contrast, can only lead us to despair of ever knowing what these things really are, or how they could ever apply to human life. Even if Plato is correct in “Assuming that there is some single good which different things possess in common, or that there exists a good absolutely in itself and by itself, it evidently is something which cannot be realized in action or attained by man” (Ethics 1096b 32-34). Aristotle, on the other hand, presents us with universals that we can discover through study, and which we can employ through our actions in this world. We can believe in things as they are, because they are here, not in some realm that, by definition, and despite Plato’s objections, lies beyond the reach of human comprehension. Plato’s theory of Forms fails in its attempt to give us standards by which to live, but Aristotle corrects the incoherencies and allows us access to universal truths.