Against Platonism about Universals

Nothing belonging as a Universal is a Substance

"I call universal (καθόλου) that which is by its nature predicated of a number of things, and particular (καθ᾿ ἕκαστον) that which is not; man, for instance, is a universal, Callias a particular" (Aristotle, On Interpretation 17a).

καθόλου is a an adverb. It means "on the whole, in general." In authors before Aristotle, it is written καθ' ὅλου (from κατά ("according to") and ὅλου (adjective, "whole, all")).
In the Metaphysics, unlike in the Categories, Aristotle denies that universals are substances.

The Problem of Universals

"Socrates... sought in ethical matters the universal (τὸ καθόλου) and was the first to set thought on definitions. Plato followed him and assumed that the problem of definition is concerned not with any sensible thing but with entities of another kind; for the reason that there can be no common definition among the sensible things, as they are always changing (ἀδύνατον γὰρ εἶναι τὸν κοινὸν ὅρον τῶν αἰσθητῶν τινός, ἀεί γε μεταβαλλόντων). These entities he called ideas" (Metaphysics I.6.987b).

"But whereas Socrates regarded neither universals (τὰ καθόλου) nor definitions as existing as separate (χωριστὰ), they separated them and called these entities ideas. Hence on their view it followed by virtually the same argument that there are ideas of all terms which are predicated universally [or: from this, they inferred that there are ideas of all the things said according to the whole (τῶν καθόλου λεγομένων)] (Metaphysics XIII.4.1078b).

"They considered that the particulars in the sensible world are in a state of flux, and that none of them persists, but that the universal exists besides them and is something distinct from them" (Metaphysics XIII.1086b).
The problem of universals in part is the problem of universal and hence necessary truths. Suppose that every man (human being) is a rational animal. Plato, it seems, thought that what makes such a proposition true is the existence of general objects he call forms. When we grasp the form man, we know that to be a man is to be a rational animal. Further, because what man is is not subject to change, these forms do not exist among the sensible objects.

We can understand this a little more clearly once we understand the truths themselves.

When we say what is true of every man (that, for example, every man is rational animal), we are saying something about what is common to all men. In this particular case, we are saying of what is common that it includes being a rational animal. What is common must somehow be real. Otherwise there would be no universal truths about human beings.

The philosophical problem is to explain in what the reality of what is common consists, and Aristotle takes Plato to try to solve the problem in terms of the existence of forms.

Toward a New Solution

Aristotle rejects Plato's solution, but he finds his way to this rejection in two steps.

In the Categories, general objects exist. Man exists in addition to the individual men. Man is a general object. Man, however, is not a primary substance. It is a secondary substance. In this way, although man is part of the ontology, it is not one of the most basic objects.

"It seems that separateness and a this belong most of all to substance (τὸ χωριστὸν καὶ τὸ τόδε τι ὑπάρχειν δοκεῖ μάλιστα τῇ οὐσίᾳ)" (Metaphysics VII.1029a).

"It is evident that nothing belonging as a universal is a substance, as nothing predicated in common signifies a this (φανερὸν ὅτι οὐδὲν τῶν καθόλου ὑπαρχόντων οὐσία ἐστί, καὶ ὅτι οὐδὲν σημαίνει τῶν κοινῇ κατηγορουμένων τόδε τι)" (Metaphysics VII.1038b).
In the Metaphysics, Aristotle takes the second step in his rejection of the Platonic solution. In the Categories, general objects exist but are not primary substances. In the Metaphysics, they are not part of the ontology. Socrates, for example, is a man, but man does not exist.

It seems, then, in the Metaphysics, that Aristotle has become a nominalist about universals. The phrase 'every man' is used in sentences that say something about every individual man, but only the individual men exist. Man does not exist. The term 'man' is significant, but it does not refer to an object. In a way, then, the reality of the universal man is no more than its name.

The Reality of the Kind

If only particulars exist, and there is no general object man whose presence makes something a man, we may wonder how Aristotle explains the fact that natural bodies fall into kinds.

"Those who speak of the forms in one way speak rightly that they are separate, if they are substances, but in another way wrongly, in that they say the form is the one over many (Metaphysics VII.16.1040b). The answer, it seems, is that Aristotle appeals to forms, just as Plato does. The difference, however, is that for Aristotle the form of a natural body is particular object.

Aristotle thinks that the forms of natural bodies are the organizations of the material so that there are the objects that belong the natural kind. Further, these organizations are all the same. Human beings, for example, are all have the same organization. Every human being has the form of a rational animal. This, according to Aristotle, is fact about the world.

Reply to the Platonic Argument

"I say the substance without matter is the what it is to be (λέγω δὲ οὐσίαν ἄνευ ὕλης τὸ τί ἦν εἶναι)" (Metaphysics VII.1032b).

"For if the line when divided perishes into its halves, or the man into flesh and bones and sinews, it does not follow that they are constituted out of these as parts of their substance (οὐσίας), but rather as matter; and these are parts of the composite, but not of the form and of which the account is; and therefore neither are they included in the accounts" (Metaphysics VII.11.1035a).

"For things that are seen to be induced in specifically different materials, as, e.g., a circle is in bronze and stone and wood, it seems clear that neither the bronze and the stone belong at all to the substance of the circle, because it is separate (χωρίζεσθαι) from them. As for things which are not seen separated, there is no reason why the same should not apply to them; e.g., if all the circles that had ever been seen were bronze; for the bronze would be none the less no part of the form..." (Metaphysics VII.11.1036a31).

"[W]e have shown that the material parts of a thing cannot be present in the account of the substance (since they are not parts of that substance, but of the composite substance..." (Metaphysics VII.11.1037a).
Plato, in the Phaedo, has Socrates argue that forms have an existence separate from the existence of the sensible things because they are "always flowing" and the forms are not. If for Aristotle the forms of natural bodies are "in matter," and so not separate from the sensible things, then we may wonder why he thinks what the natural bodies are is not subject to change.

It can be tempting to think the answer has something to do with Aristotle's thought that the forms of natural bodies are "separate in account." He thinks, it seems, that these forms have no material parts. The form of a human being exists in flesh and blood, but no such material is part of what the form is. In this way, although the form is "in matter" and so is not completely separate from the existence of sensible things, it is separate from them in account.

It is difficult, though, to work out this response to the Platonic argument in sufficient detail for it to be understandable enough to determine whether in fact it is Aristotle's response.

Here is one way to formulate the Platonic argument for the universal man:

  1.  The sensible things are "always flowing."
  2.  Man is something common, and it is not subject to change.
  3.  If (1) and (2) are true, man is general and exists separately from the sensible things.
  4.  Man is general and exists separately from the sensible things.

Aristotle, it seems, thinks that what follows from (1) and (2) is that "man is general and is separate from matter in account." The form of a human being is particular, but because each is an organization that makes the material be a body of the same kind, man is general. If rational animal is what man is, then each organization makes the material a rational animal.

More difficult to see is how "separate from matter in account" fits into Aristotle's response to this argument. The idea in the argument is that the universals must exist separately from the sensible things because otherwise the univerals would be subject to change. In reply, Aristotle seems to think that "in matter and separate in account" is separateness is enough for the universal not to be subject to change. Why he thinks this, however, is not easy to see.

Perseus Digital Library:

Aristotle, Metaphysics

Henry George Liddell, Robert Scott, A Greek-English Lexicon:
καθόλου (from καθ ὅλου), katholou, adverb, "on the whole, in general"

"[L]ike men who are unable to express themselves I won't try to deal with the matter as a whole (κατὰ ὅλον) but will take up a part and use it as an example to try to show you my meaning" (Plato, Republic III.392d).

τι, ti, indefinite prounoun, (τόδε τι = "a this," "some this," "a something")
τόδε, tode, demonstrative pronoun, "this"
χωριστός, chōristos, adjective, "separable"

"[In Metaphysics Z 13, Aristotle] argues at length that no universal can be a substance. But since he also wants forms to be substances, he has to deny that forms are universal. And, in fact, we do find him claiming that the form of a particular object is peculiar to that object, just as its matter is; Socrates' form, i.e., his soul, is different from Plato's form, i.e., Plato's soul (Met. Δ 1, 1071a 24-29). We even find Aristotle claiming that the form is a particular this (a tode ti [a τόδε τι]; 8, 1017b 25; Η I, 1042a 29; Δ 7, 1049a 28-29; De gen. et corr. 318b 32). And, of course, he has to claim that a form is a particular this, if he wants forms to be substances, since he assumes that a substance has to be a particular this. It was for this reason that Aristotle rejected the claim of matter to be substance; matter is only potentially a particular this" (Michael Frede, "Substance in Aristotle's Metaphysics," 77. Essays in Ancient Philosophy, 72-80).

"It is a basic nontrivial fact about the world [according to Aristotle] that things come with forms that are exactly alike, and not just sufficiently similar to class them together in one kind. The reality of kinds amounts to no more than this: that the specification of the form of particular objects turns out to be exactly the same for a variety of objects. But for this to be true, there is no need for a universal form or a universal kind, either a species or a genus. And, in fact, the import of [Metaphysics] Z 13 seems to be that there are no substantial genera or species in the ontology of the Metaphysics" (Michael Frede, "Substance in Aristotle's Metaphysics," 78. Essays in Ancient Philosophy, 72-80).

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