that exist. He points out that Plato asserts that the Forms and sensibles exist. Plato never says anything to indicate that sensibles (those which both are and are not) do not exist. Vlastos claims that, while Plato held that the Forms were of greater reality than sensibles, both grades of reality exist nonetheless.52 We have Vlastos' summation:
When the sensible instance is said to be less real than its Form, this is not said to ambiguate its existence, but on the contrary to disambiguate the sort of existence it has. By the same token the Form is said to be "really real" not to assert, but to categorize, its existenceto tell us what kind of existence it has.53
This leads us directly into some potential ontological difficulties. As Vlastos has it then, existentially speaking, Forms and sensibles (particulars) are of the same type, in the sense that they are both existing objects. If Vlastos held the contrary view, and maintained that Forms and particulars were of categorically differing types, then "to be and not to be" would have to be taken literally as indicative of these opposed categoriesbeing versus non-being. Vlastos' point seems to be that Forms and particulars are radically different with respect to their qualitative degree, that is, the degree to which they reflect or correspond to a Form or definition. Particulars are said to be deficiently real or less real in the sense that they are approximate "images" or reflections of qualities, which in Forms find "complete" or "perfect" expression. However, it seems that to speak of degrees of reality, and make use of such comparatives as greater or lesser, is to necessarily assimilate particulars and Forms categorically for purposes of qualification and comparison. Things of fundamentally different types, or categories, cannot be compared by degree, since they are not in the same set to begin witha qualitative spectrum would be meaningless in such a context. It can be argued that predication can only make sense if it supervenes on a fundamental ontology.
Forms clearly function, in the early and middle dialogues, as standards and paradigms. Plato's theory of predication admirably supplements a fundamental thesis of his ontology.54
A particular is deficient with respect to a Form insofar as it possesses in "merely approximate or comparative degree"55 a property that the Form, which is the character, has "perfectly" or "completely."56 But this model of comparison by degree, as Allen points out, "assimilates the Form categorically to the class of things it defines." The degrees of reality theory implies that the deficiency of particulars is one of quality, rather than type. Some quality F is had perfectly by Formswhich
is the quality itselfand to a lesser, deficient degree by particulars. Allen argues that particulars are deficient in the sense that they are of a fundamentally different type than the perfect Forms, of which they are mere "imitations."
The deficiency in question is that of one type of thing with respect to something of another type: 'deficiency' is here a category distinction, not a distinction within categories.
It could be argued, against Vlastos, and along with Allen, that this assimilation of Forms and particulars seems to be exactly what Plato is not doing in Republic Bk. V. How can we "disambiguate the sort of existence" or "kind" of existence of graded elements of the same existential type? In referring to "what participates in both being and not being" is not Plato distinguishing two different ontological categories? Plato does not merely say that sensibles are less real and leave it at that. Sensibles participate in being and not being57; they are qualified by opposites, not merely by a deficient correspondence to perfect Forms, since then Forms would only be perfect particulars. They are not just deficient qualitatively, but categorically.
Particulars are deficient not because they have the characters they have but because they are the kind of things they are...58
We have seen that both the existential and predicative positions have their strengths and weaknesses. It is possible to generate arguments for and against either position. We will now turn from philosophical arguments to direct applications of the existential and predicative models to Bk. V in order to determine the conditions for accepting one interpretation over the other. I intend to show that Bk. V, taken together with Plato's conception of change, or flux, does not adequately furnish the conditions for making a decisive judgement.
The Existential and Predicative Models in the Republic Bk. V (476a-478e)
We have briefly considered the existential and predicative positions. However, in order to come to some conclusion on the matter, we must apply these two models to our analysis of Republic Bk. V (476a-478e). By considering these formulations explicitly and evaluating their consistency with the text, we can then either decide which interpretation is more accurate given the relevant difficulties or conclude that a decisive judgement is unwarranted.