Plato (427–347 BC)

DOI: 10.4324/9780415249126-A088-1
Version: v1,  Published online: 1998
Retrieved June 19, 2024, from

15. Critical dialogues

Parmenides is that rare phenomenon in philosophy: a self-critique. Plato here makes his own theory of Forms the subject of a penetrating scrutiny which today continues to command admiration for its ingenuity and insight. Theaetetus (datable to soon after 369 bc) also reverts to Plato’s critical manner. It applies an enriched variant of the Socratic elenchus to a sequence of attempts to define knowledge. The confidence of Phaedo and Republic that Platonist philosophers are in possession of knowledge and can articulate what it consists in is nowhere in evidence, except in a rhetorical digression from the main argument. Methodological preoccupations are dominant in both works. Parmenides suggests that to defend the Forms against its critique, one would need to be much more practised in argument than is their proponent in this dialogue (a young Socrates fictively encountering a 65-year old Parmenides and a middle-aged Zeno). And it sets out a specimen of the sort of exercise required, running to many pages of purely abstract reasoning modelled partly on the paradoxes of Zeno of Elea, partly on Parmenides’ deductions in the Way of Truth (see Parmenides §§3–8). Theaetetus likewise presents itself, initially more or less explicitly, later implicitly, as a model of how to go about testing a theory without sophistry and with due sympathy. While the conclusions achieved by this ’midwifery’ – as Socrates here calls it – are as devastatingly negative as in the early dialogues, we learn much more philosophy along the way. Many readers find Theaetetus the most consistently rewarding of all the dialogues.

A sketch of the principal concerns of the two dialogues will bring out their radical character. Parmenides raises two main questions about Forms. First, are there Forms corresponding to every kind of predicate? Not just one and large, or beautiful and just, familiar from the middle period dialogues, but man and fire, or even hair and dirt? Socrates is represented as unclear about the issue. Second, the idea that other things we call for example ’large’ or ’just’ are related to the Form in question by participation is examined in a succession of arguments which seek to show that, however Forms or the participation relation are construed, logical absurdities of one kind or another result. The most intriguing of these has been known since Aristotle as the Third Man: if large things are large in virtue of something distinct from them, namely the Form of Large, then the Large itself and the other large things will be large in virtue of another Form of Large – and so ad infinitum.

Theaetetus devotes much of its space to considering the proposal that knowledge is nothing but sense perception, or rather to developing and examining two theories with which that proposal is taken to be equivalent: the view of Protagoras (§3) that truth is relative, since ’man is the measure of all things’, and that of Heraclitus that everything is in flux, here considered primarily in application to the nature of sense perception. The dialogue is home to some of Plato’s most memorable arguments and analogies. For example, Protagoreanism is attacked by the brilliant (although perhaps flawed) self-refutation argument: if man is the measure of all things, then the doctrine of the relativity of truth is itself true only in so far as it is believed to be true; but since people in general believe it to be false, it must be false. The next section of Theaetetus worries about the coherence of the concept of false belief. Here the soul is compared to a wax tablet, with false belief construed as a mismatch between current perceptions and those inscribed on the tablet, or again to an aviary, where false belief is an unsuccessful attempt to catch the right bird (that is, piece of knowledge). In the final section the interlocutors explore the suggestion that knowledge must involve the sort of complexity that can be expressed in a logos or statement. Socrates’ ’dream’ that such knowledge must be built out of unknowable simples fascinated Wittgenstein (§5), who saw in it an anticipation of the theory of his Tractatus.

Are we to infer that in opening or reopening questions of this kind Plato indicates that he is himself in a real quandary about knowledge and the Forms? Or is his main target philosophical complacency in his readers, as needing to be reminded that no position is worth much if it cannot be defended in strenuous argument? Certainly in the other two dialogues grouped here with Parmenides and Theaetetus the theory of Forms is again in evidence, presented as a view the author is commending to the reader’s intellectual sympathies. Cratylus is a work whose closest philosophical connections are with Theaetetus, although its relative date among the dialogues is disputed. It is a pioneering debate between rival theories of what makes a word for a thing the right word for it: convention, or as Cratylus holds, a natural appropriateness – sound somehow mirroring essence (see Language, ancient philosophy of §2). Underlying Cratylus’ position is an obscurely motivated commitment to the truth of Heracliteanism (see Cratylus). For present purposes what is of interest is the final page of the dialogue, which takes the theory of Forms as premise for an argument showing that the idea of an absolutely universal Heraclitean flux is unsustainable. As for Phaedrus, it contains one of the most elevated passages of prose about the Forms that Plato ever wrote.

The context is an exemplary rhetorical exercise in which Symposium’s treatment of the philosophical lover’s attraction to beauty is reworked in the light of Republic’s tripartition of the soul. Subsequently Plato has Socrates dismiss the speech as ‘play’, useful only for the methodological morals about rhetorical procedure we happen to be able to derive from it – together with a preceding denunciation of love by Socrates, capping one by his interlocutor Phaedrus – if we are dialecticians. This comment has led some readers to conjecture that Phaedrus accordingly marks Plato’s formal leave-taking of the theory of Forms: in retrospect he sees it more as rhetoric than as philosophy or dialectic, which will henceforward confine itself to something apparently less inspiring – the patient, thorough, comprehensive study of similarities and differences. Yet Phaedrus is pre-eminently a dialogue written not to disclose its author’s mind, but to make demands on the sophisticated reader’s. Perhaps Socrates’ great speech on the philosophical lover is ‘play’ not absolutely, but only relative to the controlling and unifying preoccupation of the dialogue, which is to work through a fresh examination of rhetoric, going beyond Gorgias in explaining how it can be a genuine form of expertise, based on knowledge of truth and variously geared to the various psychological types to which oratory addresses itself. We might speculate that Plato writes the speech as he does precisely because he thinks or hopes many of his readers will be of a type persuadable to the philosophical life by its vision of the soul’s desire for the Beautiful.

Citing this article:
Schofield, Malcolm. Critical dialogues. Plato (427–347 BC), 1998, doi:10.4324/9780415249126-A088-1. Routledge Encyclopedia of Philosophy, Taylor and Francis,
Copyright © 1998-2024 Routledge.

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