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Plato on knowledge and perception in Theaetetus


To: Julian P.
From: Geoffrey Klempner
Subject: Plato on knowledge and perception in Theaetetus
Date: 15 November 2004 14:05

Dear Julian,

Thank you for your email of 4 November, with your University of London essay in response to the question, 'How does Plato go about refuting the definition of knowledge as perception? Is he successful?'

This is a very thorough answer to the question, which sticks close to the text, and also shows an awareness of competing interpretations of Plato's argument. It is very difficult to find any gaps, or indeed anything to criticize in what you have written. The thoughts that I did have, all seemed to involve issues that fall outside an answer to the question set.

For example, I wondered whether there should not be some discussion of Socrates dream, which seems to revert to the view that there is, after all, a form of knowledge (of the logical 'atoms' of experience) which is pure perception, but then I thought not. That would be an answer to a different question.

Also, the wider implications of the rejection of the 'knowledge is perception' thesis seem to raise a question mark against the very notion of 'Forms' as objects of mental perception, a direct intuitive awareness which precedes, both logically and genetically our ability to give a 'logos'. (Against this, it must be admitted that nowhere in his dialogues does Plato explicitly state these claims. It is the most convincing interepretation of what he says in the Meno and Republic, and also explains the inconclusiveness of the early Socratic dialogues.)

I agree with you in questioning whether Plato has succeeded in showing that the radical flux theory is the only one that can account for Protagorean relativism. However, the conclusion I would draw from this is that the basic error is in identifying the 'knowledge is perception' claim with Protagorean relativism.

It could be argued that in bringing in Heraclitean flux and Protagorean relativism, what Plato is trying to do is not so much (or, not simply) to give the best possible statement of the 'knowledge is perception' thesis (which is what you seem to claim) but rather - in a most spectacular fashion - to kill several birds with one stone. The advantage of this interpretation is that if Plato fails to hit his secondary targets, this does not affect the argument as directed against the primary target. He just been over-ambitious. (Or, rather, as I suspect, he knows exactly what he is doing and has his tongue in his cheek.)

A more convincing interpretation of Protagorean relativism would be in terms of the realism vs. anti-realism debate over the nature of meaning and truth, first mooted in Michael Dummett's seminal article 'Truth' (and developed by Dummett and Crispin Wright). The Protagorean relativist is the global anti-realist. I am not saying this is the only possible interpretation, but it does have the advantage of making the Protagorean theory at least defensible, or at least not so lunatic. But once again, this point falls outside the scope of your essay.

Plato's discussion of Heraclitus, as you note, is somewhat confused, with considerations introduced concerning relational properties which have nothing to do with the pure subjectivist reading.

Where Plato succeeds brilliantly is in drawing the reader further and further into the metaphysics of the 'knowledge is perception' thesis, first by making it seem plausible then in successive stages demonstrating just how crazy it is. The 'Heraclitus' and 'Protagoras' who appear here turn out to be straw men, but that's not the point.

I can see a contemporary reader fully appreciating this fact. Plato is saying, 'Now, that really would be a "Protagorean" doctrine!' rather than, 'This is what I think Protagoras believed.' Similarly with Heraclitus. I might be wrong. From the evidence of the dialogue 'Protagoras', Plato had considerable respect for Protagoras as a thinker. (He is somewhat less respectful towards the other great sophist Gorgias.)

A case could be made that the main thrust of Plato's argument - and this does count against the Socrates' dream theory - is an anticipation of Wittgenstein's attack on the notion of a 'private object'. It seems that my knowledge of this sensation is the most certain form of knowledge, just because there is no gap between subject and object where error could creep in. The sheer fact of experiencing X at this moment in time logically guarantees the existence of X. However, as you recognize in your essay, as soon as the moment is passed the certainty, the immediate contact between mind and object disappears. The very knowledge that this was a case for applying the name 'X' rather than the name 'Y' presupposes something which the strict 'knowledge is perception' theorist is not entitled to. So in the end, all one can say is 'this is this', or like Cratylus, wave one's finger. The sum of all the 'this is thises' is not human experience just as it is - as it were uninterpreted - not even my experience, but nothing at all.

All the best,