true, and hence in particular there are no definitions.147The Heracliteans are expected to insist that discourse of their own favoured kind can continue, the indeterminacy of itsreferring terms, and even (asthey must now agree) of its truth-values, accurately capturing the flux of the actual world. If, that is, this now means that their assertions are, taken as a whole, no more true than false, there is no reason to assume that they will not welcome the consequence; indeed, it could even be to real-life Heracliteansthat Aristotle isreferring when he reportsthat, according to some people, Heraclitus himself makes assertions which openly violate the Principle of Non-Contradiction (Met. Γ 3, 1005b23–6).
Socrates' objection is not that such a view of things cannot be adequately expressed in language, but simply that it postulates a world in which there can be no dialectic, and, more specifically, no definitions. Consequently, Theaetetus' definition of knowledge really doesundermine itself: it isa definition that presupposes a world in which there can be no definitions.
of rational discourse is rescued.149(By rational discourse they normally mean language as such, but if I was right in the previous section we should substitute dialectic for this—fortunately, since Plato never denies that we can talk about the sensible world, whereas he does, as I shall amplify below, deny that dialectic about it is possible.) The non-doctrinal camp limitsthe function of 179c1–183c7 to the refutation of the Protagorean–Heraclitean theory, with no inferences to be drawn about the nature even of the sensible world, beyond (at most) the conclusion that it cannot be in total flux.
Here once more, I submit, to demand a straight choice between the two competing readings impoverishes the text.
Socrates, the speaker, is altogether unaware of the existence of an intelligible world over and above the sensible: this is well conveyed by the way in which, having seen off the Heracliteans, he now refuses to continue with a discussion of Parmenides' static being, confessing that he is unlikely to understand it (183c8–184a6).150 To that extent, I think, the non-doctrinal interpretation iscorrect: Socratesissimply revealing a flaw in the internal logic of Protagoreanism, without any positive metaphysical agenda of his own.
But Plato, exercising authorial control, ensures that the Platonic implications are kept in view. In analysing flux in terms of perpetual becoming without being, he can hardly fail to be aware that he isbringing to hisreaders' mindsthe radical bipartition, first introduced in the Republic, between the becoming of the sensible and the being of the intelligible.
Compare the account of sensibles developed in RepublicV (478e7–479b10) asa basisfor acknowledging separated Forms:
‘Now that this has been established, I shall say, let him give me a reply, our good man who does not think there is a Beautiful itself and a Form of Beauty itself which always stays the same way in the same respects, but does believe in the many beautiful things—that lover of spectacles who is quite intolerant of anyone who says that the Beautiful is one thing, and likewise the Just and so on. “Of these many beautiful things, my friend,” we will say, “isthere any that will not turn out ugly? And of the many just things, any that will not turn out unjust? And of the many pious things, any that will not turn out impious?” ’
149 Cf. Cornford (1935: 101).
150 From the point of view of authorial strategy, this task can be said to be being held in reserve for the Sophist, where the stranger from Elea will have all the metaphysical expertise necessary to criticize Parmenides successfully.
‘No,’ he said. ‘It's inevitable that they should turn out in a way beautiful and in a way ugly, and so too for the other thingsyou are asking about.’
‘What about the many double things? Do they turn out half any less than double?’
‘No.’
‘And large and small things, and heavy and light things: whichever of these we say, will the things be called by them any more than by their opposites?’
‘No,’ he said. ‘Each thing will alwayshang on to both.’
‘Then is each of the many, any more than it is not, whatever someone says it is?’
There is a good deal of scholarly disagreement about the precise Platonic metaphysics implied by this passage, and it is not my intention to reopen the dispute. For on any reading (even one where the ‘many beautiful things’ are limited to typesrather than tokens, assome interpretersbelieve),151it would be implausible to deny that the fluidity of particulars asdescribed here, and the fluidity of everything asdescribed in the Heraclitean theory of the Theaetetus (especially at 152d2–e1), bear a striking and non-accidental resemblance. Both accounts emphasize that each bearer of a given property will also turn out152to bear the opposite property, so that it will not be more correctly described by the one than by the other.153And both infer from this that such items cannot correctly be said to ‘be’—that is, as I understand it,154to be whatever ispredicated of them. In the Republic passage that inference is just beginning to emerge: the ‘many beautiful things’ are said in the immediate sequel to ‘fluctuate between being and not being’; it isin the subsequent two booksthat the verb ‘become’ is used to describe this intermediate state, just as in the Theaetetus.
151 e.g. Gosling (1960); Irwin (1977); contra, White (1978).
152 The verb φαὶνεσθαι followed by a simple predicate is used in both passages, and may be translated e.g. ‘turn out’. That it doesnot mean merely ‘appear’ is suggested in both passages by the direct inference from how something ‘turnsout’ to what it iscorrect to call it.
153 I avoid talk of ‘compresence’ of opposites, because this is often understood as excluding a temporal succession of opposite properties, whereas Plato does not consider ‘F at time T, but un-F at time ’ relevantly different from ‘F in aspect A, but un-F in aspect ’, where the aspects in question may be contemporaneous: cf. Smp.
210e6–211a5. An item's ‘turning out’ (see previous note) to have opposite properties covers both of these.
154 The meaning of ‘be’ in this passage is much disputed, but 479b6–10 favourstaking it to be functioning in a predominantly predicative way (I am reluctant to talk about different ‘meanings’). Cf. the illuminating discussion in Brown (1994: 220–8).
To acknowledge that the Heraclitean thesis developed in the Theaetetus corresponds to one half of this two-world metaphysics of being and becoming does not require a perfect identity between the two. What matters from the point of view of the interpretation I am proposing isthe following: Plato isasking usto notice how the Heraclitean world whose profile Socratesdevelopsprefigures the sensible world as analysed in Platonic metaphysics. To say that the Platonic sensible world is Heraclitean in character is no novelty, but articulates a widely favoured reading of Plato which goesback at least to Aristotle.155Whether or not we believe Aristotle (as I myself do) when he tells us that Plato originally learnt this Heracliteanism from his early mentor Cratylus, we have at least now seen very good reason to accept Aristotle's accompanying assertion that Plato's sensible world is a Heraclitean one. For Plato himself seems to be telling us just that by contriving so close a parallelism between the Theaetetus and Republic passages.
The Theaetetus hasshown Socratesarguing that, if the entire world isin flux, dialectic is impossible. How then is dialectic to be rescued? The Socrates of the dialogue, who has no inkling of a realm of Being separate from the sensible world, hasseen no further than the need to abandon any doctrine of total flux. But that isnot Plato'sown position: he would point, rather, to the recognition of stable Forms as the necessary condition of dialectic, since dialectic is about Forms, not sensibles. This is made abundantly clear by the Republic, which, having distinguished particulars from Forms in the way we have seen, goes on explicitly to make these latter the sole objects of dialectic (511b3–c2).156 Thanks to the postulation of Forms, Plato, unlike Socrates, can afford to leave the sensible world in a state of total flux which excludesall being (Timaeus 27d5–28a4).
From our privileged viewpoint we are enabled to recognize in Socrates, not the discoverer of these metaphysical truths, but the one who paved the way to them by developing the expertise of dialectic. It was Socrates, the philosopher who turned philosophy from the physical world to the world of pure discourse, who intuited that the ineliminable ambiguities of the sensible world bar it from being the subject of that dialectic.
155 Aristotle, Met. A 6, 987a 32–b 7. Cf. Irwin (1977) for a defence.
156 Cf. Prm. 135b5–c4, on the need for Forms if dialectic is to be possible.