The Theory of the Forms as Portrayed Throughout Plato`s Dialogues Essay
The Theory of the Forms as Portrayed Throughout Plato`s Dialogues
Prologue to Plato’s Theory of Forms
Plato’s Theory of Forms suggests the dichotomy between the material world and the world of ideas. In the Republic, Plato clearly delineates the difference between the two by first arguing that the material world, or the world which we live in, is not a perfect world and one that is full of error. On the other hand, the world of ideas is the perfect world. In such world, the Forms exist.
The forms are the perfect entities upon which the structure or the essence of the material objects in the world are based. That is, the forms serve as the foundation not only of the physical structure of the objects in the world but also of the true composition of things apart from their corporeal composition. The forms correspond to the “blueprints” of the worldly objects.
The argument of Plato that the forms are the bases for the essence and, hence, the composition of things consequently implies the argument that the forms have a higher degree of significance than the worldly objects. Part of the reason to this is the notion that without these forms the corresponding corporeal objects in the material world will not come into existence. Thus, the primacy of the forms is held with significant value throughout the philosophy of Plato.
Moreover, Plato argues that one cannot exactly derive the essence of things in the material objects themselves for the reason that these objects do not inherently have in them their “essence”. Although to a certain degree one may be inclined to claim that the worldly objects manifest the essence they intrinsically hold through the use of the sense, Plato thinks otherwise.
One reason to this argument is the Platonic belief that our senses cannot give us a full and accurate account of the nature of things. Though our senses of perception may provide us with immediate perception on the objects which are within the proximity of our consciousness, Plato contends that our senses are so limited that we cannot actually grasp in full detail what it is that these objects hold in themselves. Further, even if we are able to sensibly acquire the sensory manifestation of these objects, it remains that we are still bereft of the essence of these objects because they do not have in them the essence that provides for the very structure of their existence.
However, we must be reminded that Plato suggests that man essentially holds within him the genuine form of knowledge and the understanding of the world. This is what man basically possesses within him, something which is so intrinsic that it cannot have been originally from beyond man himself. Further, knowledge for Plato is a type of recollection wherein each individual is reminded of the forms through his or her sensory experience of the objects in the world.
In his allegory of the cave, Plato further strengthens his claim on the primacy of the forms and the failure of the conventions set forth by the senses to provide us with the knowledge on the essence of things. Citing that human beings are like prisoners in a cave who have not seen the “reality” of the objects that they merely perceive as shadows, Plato goes on to argue that we ought to be relinquished from such a fixed state. Consequently, once man finds himself liberated from the chains that have tied him down inside the cave, he then can begin to ascend out of the cave and into the world “outside”.
The transformation does not easily arrive at a point of full realization for the reason that man’s eyes will apparently be hurt by the light coming from the sun. Thus, it can be emphasized that Plato suggests that the process of acquiring true knowledge is one which is not an easy task and may hurt the sensibilities of man. Part of the reason to this is the fact that man throughout the course of his life has been so acquainted with the seeming knowledge of things given to him through convention that he tends to easily accept what is offered by his senses without even beginning to question the validity of these sensory experiences.
Nevertheless, Plato holds that our sensory experiences also hold an initial role in the process of realizing genuine knowledge. It is through our very experiences that we get immediate understanding of the empirical existence of objects and that these events serve as the starting point of the far more noble task of obtaining true knowledge beyond the confines of human convention.
For the most part of Plato’s theoretical framework on the essence of objects and the acquisition of true knowledge, one can begin to assess these concepts in terms of their validity through logic. That is, if indeed what we are merely able to grasp through sensory experiences are those which are simply based on the corporeal existence of objects and not strictly on their “essential” level, the question remains as to how exactly will we, as human beings, be able to arrive at true knowledge. Or far more importantly, the more fundamental question is on how we can be able to even begin the “painstaking” task of gaining the essence of things.
If we are to adopt Plato’s scheme in arriving at the understanding of the forms in the world of forms, one should critically assess the measures that must be done and the goals that must be met in the long run. Having this as guidance will lessen sensory deterrence to the task of grasping the forms.
In conclusion, Plato’s theory on the distinction between the world of forms and the visible or material world is one which sharply demarcates the limits of the senses. It brings into light the argument that human beings, as essentially endowed with sensory capabilities, cannot escape the error brought forth by the limits of the senses. Nevertheless, even with the imperfectness of man’s senses, one has no other starting point in advancing a grander goal than through these basic senses. The world of ideas may or may not actually exist, but the far more important question is whether indeed the material world cannot provide us the essence of things and that beyond the sense everything is in perfect state.
Socrates believes that correct answers to ‘What is F?’ questions specify forms; forms are the objects of definition where, as we have seen, definitions are real definitions. The ontological correlates of real definitions are real essences, non-linguistic universals that explain why things are as they are. Anything that is gold, for example, has the real essence of gold and is gold precisely because it has that real essence. So, as Socrates says, the one thing by which all Fs are F is a form (Euthyphro 5d1–5; Meno 72c7). Or again, he says that the form of piety is some one thing, the same in (en; Eu. 5d1–2; cf. Ch. 159a1–2, 158e7) everything that is pious; it is that feature of things by which they are pious.
On the account I have been suggesting, Socrates offers an epistemological argument for the existence of forms: the possibility of knowledge requires explanation, and this, in turn, requires the existence of forms—real properties and kinds. He also offers a metaphysical one over many arguments for the existence of forms: the existence of many Fs requires the existence of some one thing, the form of F, in virtue of which they are F.[i]
David Armstrong has usefully distinguished between realist and semantic one over many arguments.21 Realist one over many arguments posit universals to explain sameness of nature; if a group of objects are all F, they are F in virtue of sharing a genuine property, the property of F. (A predicate nominalist, by contrast, would say that they are all F because the predicate ‘F’ is true of them all; we need not postulate a genuine property that they all share.) Semantic one over many arguments posits universals to explain the meanings of general terms and, indeed, universals just are the meanings of those terms. On the account of Socrates that I have provided, he offers not a semantic but a realist one over many arguments. For, as we have seen, he wants to know not the meanings of general terms, but the properties in virtue of which things are as they are.
If forms are properties whose range and nature are determined by explanatory considerations rather than by considerations about meaning, then they are not meanings, if meanings are taken to be something other than properties conceived in realist fashion. But might Socrates view forms as meanings, and take (some) meanings to be properties? He presumably would do so if he accepted a referential theory of meaning.
However, it has been cogently argued that Socrates takes the virtue terms to be non-synonymous but co-referential, so he cannot consistently accept a referential theory of meaning.[ii] But is Socrates inconsistent? Or does he confusedly view forms not only as properties but also as meanings, where meanings are taken to be something other than properties? It is difficult to be sure, since he does not discuss semantic questions. But so far as I can see, he does not suggest that forms play any semantic role.[iii]
If Socrates relies on a realist one over many arguments, then he presumably takes every property to be a form. To be sure, he does not explicitly say how many forms there are; as Aristotle says, Socrates is primarily interested in the virtues. But he never suggests a principle that restricts forms to a subclass of properties; and he sometimes explains why each of the virtues is some one thing, and so a form, by appealing to quite heterogeneous sorts of cases.[iv]
Although Socrates seems to believe that every property is a form, he is not committed to the view that every predicate denotes a form. For, again, forms are explanatory properties, and not every predicate denotes an explanatory property.
In addition to suggesting that Socratic forms are universals conceived as explanatory properties, and that on Socrates’ view knowledge of them is necessary for having any knowledge at all, Aristotle also claims that Socrates did not take forms to be either non-sensible or separate. I turn now to these claims.
One might argue that Aristotle is wrong to say that Socrates did not take forms to be non-sensible; on the ground that Socrates routinely rejects answers to ‘What is F?’ questions that are phrased in terms of behavior or action-types. Moreover, at least in the case of the virtues he seems to favor accounts that are phrased in terms of certain states of the soul and these, it might be thought, are not observable. It might then be tempting to infer that Socrates believes that a correct answer to a ‘What is F?’ question must specify a non-observable property, a property not definable in observational terms.
However, although Socrates regularly rejects answers to ‘What is F?’ questions that are phrased in observational terms, he never says that they fail because they are so phrased. They fail, as we have seen, because they are too narrow or too broad, or because they are not explanatory; but Socrates does not link these failures to the fact that the answers are phrased in observational terms.
He leaves open the possibility that although the proposed accounts fail, some other account phrased in observational terms might be satisfactory. This, however, is enough to vindicate Aristotle if he means only that Socrates does not explicitly say that forms are non-sensible, and so in that sense is not committed to the claim that they are; and that seems to be all Aristotle means.[v]
What, now, about separation? Discussions of separation are difficult, partly because ‘separation’ is used differently by different people. I shall follow Aristotle’s lead and say that A is separate from B just in case A can exist without B—that is, just in case A can exist whether or not B exists or, equivalently, just in case A exists independently of B.[vi] Separation so defined is a modal notion; if A is separate from B, A can exist whether or not B exists. (Hence A can be separate from B even if A never actually exists when B does not.) Separation so defined is also a relational notion: to be separate is always to be separate from something.
In the case of forms, the relevant ‘something’ is sensible particulars (Met. 1086b4, 8).[vii] So Socratic forms are separate just in case they can exist whether or not there are any corresponding sensible particulars. If forms are universals, then to say that they are separate is to say that they can exist uninstantiated by the corresponding sensible particulars.[viii]
Socrates never explicitly says or denies that forms are separate; nor do his ways of characterizing forms seem to commit him one way or the other. He says, for example, that forms are in things (e.g. Eu. 5d1–2). But to say that forms are in things is only to say that various sensible have them, i.e. have the relevant properties. It does not follow from the fact that sensibles have properties that those properties are not separate, i.e. cannot exist unless some corresponding sensible particulars instantiate them.[ix] Other evidence seems equally indeterminate. This, however, is enough to vindicate Aristotle’s claim that Socrates did not separate universals, i.e. forms, if, as seems to be the case, he means only that Socrates is not committed to separation.[x]
I close my discussion of Socrates by considering two further claims about forms—that they are self-predicative and that they are paradigms. Although Aristotle does not mention these claims in connection with Socrates, they are important in understanding both Plato and also Aristotle’s criticism of him in the Peri ideōn; and we can get a better grip on Plato’s version of these claims if we look first at Socrates’ version.
Socrates believes that the form of F cannot be both F and not F; that is, it cannot suffer narrow compresence with respect to F-ness. It can avoid being both F and not F in one of two ways: by being neither F nor not F, or by being F without also being not F. Although the evidence is meager, Socrates seems to favor the latter option; he seems to believe, that is, that the form of piety is pious, the form of justice is just, and so on. He thus seems to accept self-predication (SP), the thesis that any form of F is itself F.[xi]
It no doubt sounds odd to say that the form of justice is just, and it may not be correct to do so. But the claim is more intelligible than it may initially appear to be. We have seen that Socrates says that various action-types and character-traits are F and not F—endurance, for example, is both courageous and not courageous. He does not mean that endurance is courageous or not courageous in the very same way in which a person might be; the property of endurance, for example, does not itself stand firm in battle.
Rather, endurance is courageous and not courageous in so far as it explains why some things are courageous and why other things are not.[xii] Socrates believes, that is, that if x explains y’s being F, then x is itself F, though not necessarily in the very same way in which y is F; rather, x is (or may be) F in a sui generis way, simply in virtue of its explanatory role.[xiii]
We can understand self-predications along the same lines. Forms are properties; the form of justice, for example, is the property of justice. Socrates believes that it is the single feature by which all and only just things are just; it is the ultimate source or explanation of what is just about just things, and it never explains why anything is not just. Socrates does not mean that it is just in the very same way in which Aristides was; he means that it is just simply in virtue of its explanatory role.
On this view, Socrates has unusually generous criteria for being included in the class of Fs; something can be a member of the class of Fs by being the source or explanation of something’s being F in the ordinary way. We might well object to these criteria; but they do not commit Socrates to the view that the form of justice, for example, can win moral medals.[xiv]
On behalf of this account of self-predication, it is worth noting that we readily predicate (e.g.) ‘justice’ in the ‘ordinary’ way of categorically different types of things—of, for example, people, acts, institutions, laws, and the like. So perhaps predicating it of the property of justice is not as radical a departure from ordinary usage as it may initially seem to be. Further, we have seen that Socrates is not shy about revising our pre-analytic beliefs; so perhaps one new belief he wants us to acquire is that the form of F is itself F.
We have seen that Socrates believes that the one thing by which all Fs are F is the form of F; he also takes this one thing to be a paradigm (paradeigma, Eu. 6e4–5), so that by looking to it (apoblepein eis; Eu. 6e4) one can know of any given thing whether or not it is F. Plato and Aristotle use paradeigma in a variety of ways. Often, for example, they use it simply to mean ‘example’.[xv] Aristotle once calls his own forms paradigms (Phys. 194b26 = Met. 1013a27), by which he seems to mean that they are the formal—structural or functional—properties of things; as such, they are explanatory natures. But as we shall see, he believes that Platonic forms are paradigms in a different, and objectionable, sense.
When Socrates says that forms are paradigms, he seems to mean only that they are standards in the sense that in order to know whether x is F, one must know, and refer to, the form of F. For x is F if and only if it has the property, i.e. form, of F; so in order to know that x is F, one needs to know what F is and use that knowledge in explaining how it is that x is F. (So paradigmatism and self-predication are closely linked. The form of F is F because it explains the F-ness of things; forms are also paradigms in virtue of their explanatory role.) I shall call this weak paradigmatism.
As I interpret Socrates, he introduces forms for epistemological and metaphysical, but not for semantic reasons. Further, Socratic forms are universals in the sense that they are explanatory properties. The fact that they are self-predicative paradigms does not jeopardize their status as explanatory properties; on the contrary, they are self-predicative paradigms because they are explanatory properties.
Compresence, Knowledge, and Separation
Why does Plato take the compresence of opposites to require the existence of non-sensible forms that escape compresence? Aristotle rightly says that the reasons are metaphysical and epistemological. The metaphysical reason is especially prominent in the famous aitia-passage in the Phaedo (96a ff.), where Plato lays out criteria for adequate explanations. In his view, if x is F and not F, it cannot explain why anything is F; it cannot, in other words, be that in virtue of which anything is F.
Since some sensible properties of F suffer compresence, reference to them does not explain why anything is F, and so they cannot be what F-ness is. Since explanation is possible, in these cases things are F in virtue of a non-sensible property, the form of F. So Plato concludes that ‘if anything else is beautiful besides the beautiful itself, it is so for no other reason than that it participates in the beautiful’ (Phaedo 100c4–6).
Or again, it is not because of ‘bright color or shape or anything else of that sort’ (100d1–2) that anything is beautiful; rather ‘it is because of the beautiful that all beautiful things are beautiful’ (100d7–8). For sensible properties suffer compresence in so far as bright color, for example, is sometimes beautiful, sometimes ugly. In Plato, the Socratic view that the form of F is the one thing by which all Fs are F becomes the view that forms are aitiai, causal or explanatory factors—at least in certain cases, things are as they are because they participate in non-sensible forms that escape compresence.
This metaphysical reason for positing forms has epistemological repercussions. For like Socrates, Plato thinks that knowledge requires explanation;[xvi] since he believes that in at least some cases explanation requires reference to forms, he also believes that in these cases one can have knowledge only if one knows the relevant forms. Since knowledge in these cases is possible, there must be forms.
This epistemological reason for positing forms is especially prominent in Rep. 5–7, where Plato asks the ‘What is F?’ question and assumes that one needs to know what F is in order to know anything about F—where, as with Socrates, the knowledge at issue is knowledge as it contrasts with belief, and where definitions are real definitions.[xvii] The sight-lovers believe that we can answer the question ‘What is beauty?’ by simply mentioning the many beautifuls (ta polla kala, 479d3)—sensible properties like bright color. For in their view each such sensible property explains some range of cases. Bright color, for example, explains what makes this Klee painting beautiful; somber color explains what makes this Rembrandt painting beautiful; and so on.
Against the sight-lovers, Plato points out that each such property suffers compresence since (e.g.) some brightly colored things are beautiful, others are ugly. In his view, if x is F and not F, it cannot explain why anything is F; so no such property can explain why anything is beautiful. Further, in his view as in Socrates’, we can explain why Fs are F only if F-ness is some one thing (479d3), the same in all cases; so F-ness cannot be a disjunction of properties. It is therefore a single non-sensible property, the form of F. This is required, in Plato’s view, by the possibility of knowledge.
Like Socrates, then, Plato posits forms as universals whose existence is necessary for explanation and so for the possibility of knowledge. He also agrees with Socrates that F-ness itself cannot be not F. Unlike Socrates, however, Plato insists that forms are non-sensible. A related difference is that Socrates countenances a form for every property. But as Plato points out in, for example, Rep. 7 (523–5), only some predicates have sensible instances that suffer narrow compresence—‘thick’ and ‘thin’ are such predicates, but ‘finger’ is not.
Like Socrates’ arguments for the existence of forms, Plato’s argument from compresence posits forms to explain, not the meaningfulness of general terms or linguistic understanding or even belief, but the possibility of explanation and knowledge. Indeed, the sight-lovers in Rep. 5 have rather sophisticated beliefs even though they do not countenance forms. Similarly, in Rep. 7 (523–5) sight can identify examples of thick and thin things, of hard and soft things; what it cannot do is define thickness and thinness, hardness and softness. For it is confined, naturally enough, to sensible properties, but in Plato’s view one cannot define thickness and thinness and so on in such terms.[xviii] Nor does the argument from compresence take forms to be particulars.
Like Socrates, Plato assumes that a correct answer to a ‘What is F?’ question will specify the property of F. His interlocutors generally seem to agree; at least, their answers are typically phrased in terms of properties (e.g. bright color). The dispute between Plato and his interlocutors is about the nature of various properties: the sight-lovers take them to be sensible; Plato takes them to be non-sensible forms.
The argument from compresence takes forms to be the basic objects of knowledge—one must know them in order to have any knowledge at all. It does not follow that forms are the only objects of knowledge. Nor is it clear why the fact that something suffers compresence should make it unknowable. Since bright color is both beautiful and ugly, it cannot be what beauty is; but it does not follow that we cannot know that bright color is both beautiful and ugly, or that something is brightly colored. Yet it is often thought that Plato takes sensibles to be unknowable, and it is often thought that Aristotle interprets Plato in this way.
I have argued elsewhere, however, that Plato is committed only to the claim that forms are the basic objects of knowledge, in the sense that in order to know anything at all one must know them; he leaves open the possibility that if one knows them one can use that knowledge in such a way as to acquire knowledge of other things. It is tempting to suppose that Aristotle agrees. To be sure, Met. 1. 6 and 13.4 can be read as saying that Plato takes whatever changes to be unknowable.
But perhaps Aristotle means only that Plato takes whatever changes to be unknowable in itself, independently of its relation to forms, so that whatever changes cannot be the basic object of definition or knowledge. Met. 13. 9 seems congenial to this interpretation. For Aristotle says there that ‘it is not possible to acquire knowledge without the universal’—a claim that plainly leaves open the possibility of knowing more than universals. Further, although he repeats the claim that Plato thinks that sensibles are always changing, he does not say that in Plato’s view that makes them unknowable. So perhaps Aristotle means to commit Plato only to the claim that forms are the basic objects of knowledge.
The argument from compresence shows that forms are different from both sensible particulars and sensible properties. But it does not show that forms are separate, i.e. that they can exist whether or not the corresponding sensible particulars exist. Difference does not imply separation. Yet it is sometimes thought that Plato, both in fact and in Aristotle’s view, argues in this invalid way.
The Metaphysics passages, however, do not saddle Plato with this invalid argument. Met. 1.6 says only that flux (i.e. on my interpretation, compresence) shows that forms are different (hetera; cf. Phaedo 74a11, c7) from sensibles; separation is not mentioned. In 13.4, Aristotle says that Plato separated forms; but he does not say why Plato did so. He mentions separation not as the conclusion of an argument, but simply as a distinguishing feature of the Platonic theory.
In 13.9, however, Aristotle explains (III (1–6); see sect. 2) that Plato inferred from the flux of sensibles that there must be forms conceived as non-sensible universals that are the basic objects of knowledge and definition. He adds (III (8–10)) that Plato took forms to be substances, i.e. basic beings; since substances must be separate, forms are separate. Aristotle seems to believe, then, that the ‘flux argument’ shows only that forms are non-sensible universals that are the basic objects of knowledge and definition; that forms are separate follows only with the aid of further premises. These further premises give Plato a valid argument for separation.
I think Aristotle is right not to claim that Plato argues from the flux of sensibles to the separation of forms; at least, Plato never does so explicitly.[xix] But is Aristotle right to say that Plato takes forms to be separate, if for other reasons? It is difficult to be sure. For one thing, Plato never says that forms are separate; he never, that is, uses any form or cognate of ‘chōrizein’ of forms, at least not in the relevant sense.[xx] Nor do any of his explicit arguments imply that forms are separate.
In the Timaeus, however, Plato seems to be committed to separation. For he says there that forms are everlasting and that the cosmos is not everlasting; there has always been a form of man, but there has not always been particular men. It follows that the form of man existed before the cosmos came into being, and so it existed when there were no sensible particular men; hence it can exist whether or not they do, and so it is separate. Now in the middle dialogues Plato sometimes says that forms are everlasting.
But he does not say that the cosmos is not everlasting, so the Timaeus route to separation is not mentioned.[xxi] Indeed, nothing said in the middle dialogues seems to me to involve clear commitment to separation. None the less, separation fits well with the tenor of the middle dialogues, and the casual way in which separation emerges in the Timaeus perhaps suggests that Plato takes it for granted. So I shall assume that Aristotle is right to say that Plato separated forms, though it is important to be clear that Plato never argues, or even says, that forms are separate.
Aristotle argues that since forms are separate, they are particulars (13. 9). Since he also takes forms to be universals, he concludes that forms are both universals and particulars. But as I (following Aristotle) understand separation, the claim that forms—universals—are separate is simply the claim that they can exist whether or not any corresponding sensible particulars exist. Why does Aristotle take this to show that forms are particulars? The answer is that he believes that universals exist when and only when they are instantiated; in his view, only substance particulars are separate (see e.g. Met. 1028a33–4). So he claims that if forms are separate they are (substance) particulars because he accepts the controversial view that universals cannot exist uninstantiated.
He is therefore not convicting Plato of internal inconsistency: he means that Plato’s views do not square with the truth. He sees that Plato introduces forms simply to be universals; that they are particulars results only if we accept the controversial Aristotelian assumption, which Aristotle takes Plato to reject, that universals cannot exist uninstantiated. Aristotle’s complaints about separation therefore rely on one of the argumentative strategies as he intrudes into Platonism assumptions he accepts but that he thinks Plato rejects. Once we see that this is what Aristotle is doing, we can see that although he claims that forms are particulars, there is a sense in which he agrees with me that they are, or are intended to be, only universals.
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[i] Plato never uses the phrase ‘one over many’ (hen epi pollōn; hen para polla). But he contrasts the one and the many, and he sometimes says that forms are para various things. (Parm. 132a11–12 has epi toutois au pasin heteron; 132c3 has some one thing which is epi pasin.)
[ii] See Penner, ‘The Unity of Virtue’, and Irwin, PMT, ch. 3. See also C. C. W. Taylor, Plato: Protagoras (Oxford, 1976), 103–8 (though Taylor is less sure than Penner and Irwin are that Socrates is clear about the difference between sense and reference; see pp. 106–7). In ‘Plato on Naming’, Philosophical Quarterly, 27 (1977), 289–301, I in effect argue that Crat.—which contains an extended discussion of names, and of language more generally—does not involve a referential theory of meaning, or confuse sense and reference. If Crat. articulates Socrates’ views, then it provides further evidence that he is not committed to a referential theory of meaning and does not confuse sense and reference. By contrast, Vlastos, ‘The Unity of the Virtues’, 227, claims that neither Socrates nor Plato ever distinguishes between sense and reference.
[iii] White, Plato on Knowledge and Reality, 9, agrees that semantic considerations are not ‘wholly explicit’ in the Socratic dialogues, but he believes that Meno 72–4 and Eu. 5c8–d5 suggest such considerations ‘less openly’. On the account of these passages that I have defended, however, they are not semantic. For both passages concern the ‘What is F?’ question, which asks not for the meaning of ‘F’, but for a real definition of F. Perhaps in mentioning the Meno passage, White has in mind 74d5–6, where Socrates tells Meno that since he calls various things by the name ‘shape’, Meno should be able to tell him what shape is.
But Socrates seems to mean only that since Meno thinks that there are various shapes, he should be able to tell Socrates what shape is—it is the fact that the name applies to something, rather than the fact that there is such a name, that suggests that shape is something. To say that if a name, ‘F’, applies to something, there is such a thing as F-ness does not imply that every general term denotes a property or form, or that forms are the meanings of the terms to which they correspond, or even that forms are relevant to explaining the meanings of general terms.
[iv] In La. 192ab, for example, Socrates argues that just as speed is some one thing, so too is courage. In Meno 72a–74a, he argues that just as being a bee is some one thing, so too is virtue.
[v] Allen, by contrast, thinks that Met. 1. 6 ‘implies that Socrates identified the objects of definition with sensibles, which is another way of saying that he did not distinguish Forms from their instances’ (Plato’s Euthyphro, 134; cf. 136). But Met. 1. 6 says only that Socrates did not take them to be non-sensible, which leaves open the possibility that Socrates did not take them to be sensible either—he was uncommitted either way.
Even if Aristotle means that Socrates took the objects of definition to be sensible, it would not follow that he thought that Socrates did not distinguish them from sensible particulars (which is what Allen seems to mean by ‘instances’). For Aristotle believes that there are not only sensible particulars but also sensible or observable properties or universals (see Ch. 2.4). And in Met. 13. 9, he commends Socrates for acknowledging the existence of universals as entities distinct from particulars, since ‘it is not possible to acquire knowledge without the universal’ (1086b5–6). If Aristotle claims both that Socrates recognized the existence of universals and also that he took them to be sensible, then the sensibles at issue here should be sensible universals rather than sensible particulars.
[vi] I take ‘A exists independently of B’ to be equivalent to ‘A can exist whether or not B exists’. To say that A is separate from B is compatible with saying that B is separate from A. If A is separate from B but B is not separate from A, then A is not only separate from but also ontologically prior to B. Ontological priority implies separation, but separation does not imply ontological priority.
[vii] In these two passages, ‘kath’ hekasta’ and ‘aisthēta’ denote only particulars..
[viii] Hence the claim that forms are separate is weaker than the claim that they can exist uninstantiated tout court. If forms can exist uninstantiated, they are separate, but the converse is not true.
[ix] If Socrates believes that a form can exist only if it is in something, then he rejects separation; for the view that he believes this, see Vlastos, Socrates, 74; cf. pp. 55–66, 72–80. (By contrast, in ‘The Unity of the Virtues’, 252, Vlastos says that Socratic forms or universals are not ‘ontological dependencies of persons’; this seems to say that they exist independently of sensible particulars, in which case they are separate.) But although Socrates assumes that forms are in things, I do not see that he commits himself to the view that they would not exist unless they were in things.
[x] By contrast, Allen, Plato’s Euthyphro, 136, argues that Socrates separated forms.
[xi] See e.g. Prot. (330c3–e2, where justice is said to be just, and piety pious); HMa. 291d1–3 (beauty ‘will never appear ugly to anyone anywhere’—though even if it never appears ugly, it does not follow that it appears beautiful); Eu. 5d1–5 (the eidos of piety is pious) and, possibly, Eu. 5d1–5 (but cf. Vlastos, Socrates, 57 n. 48); Lys. 217ce. As I go on to suggest, commitment to self-predication also seems to be tacit or assumed elsewhere.
[xii] More precisely, Socrates believes that endurance no more explains why one thing is courageous than why another thing is not. For in his view the only real—or, at least, the ultimate—explanation of anything’s being F is the one thing by which all Fs are F. But it will be convenient to speak as I do in the text.
[xiii] To say that if x explains y’s being F, it is itself F, though perhaps in a different way from the way in which y is F, is not to say that x and y are F in different senses of ‘F’. To illustrate the difference between different ways of being F and different senses of ‘F’: horses and cows are animals in different ways, but ‘animal’ means the same in ‘Horses are animals’ and in ‘Cows are animals’. ‘Seal’, however, means something different as applied to the seals in a zoo and the Great Seal of the United States; see S. Peterson, ‘A Reasonable Self-Predication Premise for the Third Man Argument’, Philosophical Review, 82 (1973), 451–70 at 464. I elaborate on this point below in discussing Plato on SP; see also Chs. 10, 15, and 16.
If x‘s explaining y‘s being F is a sui generis way of being F, then Socrates’ view of self-predication is not refuted by the fact that e.g. saccharine tastes bitter but makes other things taste sweet. Nor does saccharine therefore suffer narrow compresence of opposites, since it is not both sweet and bitter in virtue of some one and the same aspect of itself. It is sweet because it makes other things taste sweet; it is bitter because of its own taste.
[xiv] C. C. W. Taylor interprets Socrates’ notion of self-predication in a somewhat similar way, saying that ‘if justice is seen as a force in a man causing him to act justly, it is by no means obviously nonsensical to describe it . . . as just’ (pp. 119–20; contrast pp. 112–13). See also Irwin, PMT 306 n. 6. However, they seem to think that Socrates takes the form of justice, for example, to be just in the very same way in which a person is just.
[xv] In Plato, see e.g. Ap. 23b1; Gorg. 525c6–7; So. 251a7; Phdr. 262c9; Pol. 277d1; Laws 663e9. In Aristotle, see e.g. Top. 151b21, 157a14, 15.
[xvi] For Plato’s insistence that knowledge requires an account, see Phd. 76b4–6, Rep. 531e4–5, 534b3–6, Tm. 51e3. Passages in which Plato asks the ‘What is F?’ question also assume that knowledge requires an account; for he believes that one needs to know what F is in order to know anything about F, and knowing what F is involves knowing an account of it. For references to places where Plato asks the ‘What is F?’ question, see below and the next note. (In all these passages, the relevant sort of account involves explaining the natures of the relevant entities; but see n. 17.)
[xvii] For references to the ‘What is F?’ question, see e.g. Rep. 523d4–5, 524c11, e6. In Rep. 5 Plato infers from the fact that the sight-lovers do not know what beauty is that they know nothing about beauty; this assumes that one needs to know what F is in order to know anything about F. I discuss Rep. 5 further in Ch. 7. For a more detailed discussion, see my ‘Knowledge and Belief in Republic V’, Archiv für Geschichte der Philosophic 60 (1978), 121–39, and ‘Knowledge and Belief in Republic V–VII’, in S. Everson (ed.), Companions to Ancient Thought, i: Epistemology (Cambridge, 1990), 85–115.
[xviii] Rep. 523–5 is sometimes thought to concern not definitions of properties but identification of examples. For some discussion, see Irwin, PMT, ch. 6, esp. 318 n. 26, and 320–1 n. 39. I discuss this matter further, though still briefly, in ‘The One over Many’ and in ‘Plato on Perception’, Oxford Studies in Ancient Philosophy, supplementary volume (1988), 15–28.
[xix] In Phd. 74a9–c5, for example, he infers from the fact that sensible equals are equal and unequal that there must be a form of equal that is different from, non-identical with, sensible equals. Separation is not mentioned.
[xx] Neither Tm. nor the middle dialogues use any form or cognate of ‘chōrizein’ of forms. In Parm., Plato says that ‘similarity itself exists separately (chōris) from the similarity we ourselves have’ (130b4); Vlastos, Socrates, 259–61, takes him to mean that forms exist independently of sensibles, i.e. can exist whether or not they do.
However, in the just preceding lines Plato asks: ‘Have you yourself, as you say, distinguished in this way, on the one hand, separately certain forms themselves, on the other, separately, in turn, the t hings which participate in them?’ (130b1–3). Here he suggests, not that forms exist independently of sensibles, but that they can be distinguished separately from them, just as sensibles can in their turn be distinguished separately from forms. 130b4 seems to illustrate this general point by way of a particular example; it does not make a new point about existential independence.
[xxi] Actual uninstantiation is sufficient but not necessary for separation. My point is that unlike Tm., the middle dialogues are not clearly committed to this particular sufficient condition. Rep. 10 has a form of bed. If it is everlasting, presumably it has not always been instantiated, since presumably there have not always been sensible beds, in which case it is separate.