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Protagoras: man is the measure of all things


To: Edvard K.
From: Geoffrey Klempner
Subject: Protagoras: man is the measure of all things
Date: 6 June 2001 14:07

Dear Edvard,

Thank you for your e-mail of 26 May, with your fifth essay for the Ancient Philosophy program, in response to the question, 'What do you think Protagoras meant by his statement, "Man is the measure"? In the light of your interpretation, how fair is the account that Plato gives of Protagoras' doctrine in the "Theaetetus"?

As you may know, I describe myself on the Pathways site as an 'Internet Sophist'. I would number myself amongst those who would like to see the term 'Sophist' reclaimed, purged of its negative associations. (I think you would enjoy Robert Pirsig's book "Zen and the Art of Motorcycle Maintenance" which offers a vigorous defence of the sophists.)

Not all the Sophists who taught their students 'how to win arguments and influence people' cared about philosophy. I believe that Protagoras was one of those who did. Gorgias, on the other hand, seems more questionable. Yet, as I argue in the last unit of the program, he did make - despite his scorn for other philosophers, - a significant contribution to philosophy.

I am not sure that you have really answered the question set for this essay. In the 'Theaetetus', Socrates attributes to Protagoras extreme subjectivist and pragmatist views which are easily refuted. The question is whether Socrates/ Plato is attacking the real Protagoras or a 'straw man'. I suspect that to a large extent he is attacking a straw man. Even so, useful results arise from the discussion of Protagoras, which are relevant to the question which Plato is addressing, 'How is it possible to have a false belief?'

In other words, the attack on Protagoras serves a useful purpose, despite involving a highly suspect account of Protagoras' views.

Of course we don't know for sure what Protagoras meant by his 'Man is the measure' remark. I like your interpretation, according to which 'Each man must judge for himself' and not rely uncritically on the authority, or the opinions of others. That would have been a true and worthwhile thing to say. As you remark, it is 'a very important part of one's personal, subjective development'. I also see how difficult it can be to defend such a view under a totalitarian regime.

In unit 14, I suggest that one moderate reading of 'Man is the measure' is as an expression of the principle of empiricism. This is not the same as the view that each person must judge for themself. It is just another plausible candidate.

I also suggest two less moderate readings, one in the spirit of Berkeleian idealism, and the other in the spirit of contemporary 'anti-realist' theories of truth and meaning.

The Berkeleian reading would certainly fit some of the things that Plato says about Protagoras doctrine in the 'Theaetetus'. However, it is important to recognize that for the Berkeleian idealist there is an objective world, to which my ideas correspond. Berkeley did not believe that all exists is a subjective stream of momentary impressions. Berkeley held that the objective world consists in ideas in God's mind, an idea that would have been repugnant to Protagoras. Take away God, however, and we are once more faced with the problem of accounting for the existence of objects which are not perceived. If the world is made up of objects of sense, how are we to conceive of such objects prior to their being sensed? Do they pop into and out of existence? Is the world full of holes?

On balance, I prefer the alternative, anti-realist reading, although here too there is a danger of anachronism. I hear Protagoras declaring, 'I don't believe in so-called "truths" which no-one could ever know. Truth is a product of judgement rather than something external to judgement.' However, if one presses this initially plausible claim, it becomes apparent that here too, we end up with a 'world full of holes'. Suppose I shake a coin in my hand. Then I shake it again. Surely it was true that the first shake produced 'heads', or it was true that the first shake produced 'tails'? But these are truths which can never be known! So one is forced to say that the proposition, 'The first shake produced heads' lacks a determinate truth value.

Your essay will require quite a bit of work to get up to the standard of the Associate Diploma, but it has promise. I would like to see you say a bit more about the value of your interpretation, 'Each man must judge for himself'. If that is the correct interpretation, then it would certainly be the case that Plato misrepresents Protagoras' views in the 'Theaetetus'.

I look forward to seeing your first Associate Diploma essay. Aim for 2000-2500 words, if you can. You will get another shot at improving each of the four essays which you choose for your Associate Diploma portfolio before submitting the portfolio for examination. I believe you can make the grade!

All the best,