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Parmenides' argument for the proposition 'It is'


To: Namet I.
From: Geoffrey Klempner
Subject: Parmenides' argument for the proposition 'It is'
Date: 8 January 2007 10:43

Dear Namet Ilahi,

Thank you for your email of 24 December, with your essay for the Ancient Philosophy program in response to the question, 'Analyse and give a commentary on Parmenides' argument for the proposition, 'It is'.'

This is an accurate and well judged summary of Parmenides' argument.

However, the big question facing anyone grappling with Parmenides is why he insisted on asserting the exclusive alternative, 'It is and cannot not be' or 'It is not and must not be'.

You tantalisingly offer a one sentence explanation: 'These conclusions are based on the argument that one can never prove the non-existence of something.' In itself, this claim is not altogether implausible, so let's see how it goes. How would you go about proving the non-existence of unicorns? We could conduct a very thorough survey, but there would be no way to be sure that a unicorn had not existed in the dim distant past, and died without leaving a trace. Or, even if we were sure that no unicorns exist or ever existed on Earth, there is still the rest of the universe to explore.

However, the problem does not have to be put in those terms. It is not so difficult to prove the non-existence of a unicorn sitting at this desk typing these words. An observer only has to look. Being a human being is, by definition, inconsistent with being a unicorn. In other words, the fact or facts in virtue of which it is true that there is not a unicorn sitting here are that there is a human being sitting here.

In this sense, it might be claimed that every negative is a necessary negative. It is not necessary that a human being was sitting here. My seat might have been occupied by a unicorn. But as a matter of contingent fact, this not the case. My seat is occupied by a human being. And it follows by logical necessity from this fact that it is not occupied by a unicorn. 'All determination is negation,' as the Medieval principle says.

It might seem that I am labouring this, but we are faced with the hugely puzzling fact that Parmenides refused point blank to accept this account. Why?

In the unit on Parmenides, I try to give a possible explanation. I am not at all confident that it is correct. There are other explanations.

This is the 'game' that Parmenides scholars play, either trying to find the most plausible explanation for a view which they agree is false, or finding some novel interpretation in terms of which Parmenides turns out to be saying something true after all.

For example, it has been claimed (I seem to recall, originally by Karl Popper) that Parmenides is talking about 'the truth' as such. Either there is such a thing as 'the truth' or not. Belief in the existence of 'the truth' is the way of sanity and reason. Disbelief is the way of insanity and chaos. The battle between 'realists' who believe in truth, and 'anti-realists' or 'constructivists' is one of the major themes of 20th century philosophy. However, if this interpretation is correct, it is hard to see why Parmenides thinks it follows that change and differentiation must be excluded from the reality of 'it is'.

And what about the 'third approach'? This is the other intriguing question. You offer the explanation, 'This could happen when two persons discuss an object about whose attributes their knowledge differs - one may know the attributes 'a' to 'm' and the other the attributes 'h' to 'n'.'

I wonder about this. When two people know different things about an object, they don't necessarily disagree - in fact, if we are talking about knowledge then logically this rules out disagreement. If there were any disagreement, e.g. whether or not the object had attribute 'c', then as a matter of logic one of the two people must be wrong. Either the object has 'c' or it doesn't. But in that case, there is no claim, 'it is and is not'. If the object has 'c' then it has 'c' and it is wrong to assert that it does not have 'c'.

What exactly are the alternatives? Let's run through this again:

(a) It is. Parmenides' theory of the One is correct.

(b) It is not. There is no 'One', no 'truth', no 'reality' or however you want to describe it.

(c) What most muddle-headed mortals believe, that some things are 'real' and 'true', but other things are 'not', whatever that means.

To me, this is the especially striking part of Parmenides argument. He seems to be saying, in effect, 'You already half-believe what I'm trying to tell you, but you want to have things both ways. You refuse to accept the full logical consequences.'

What I would like to suggest is that this provides an extra handle on the argument for 'It is'. Whatever that argument may be, it has to be one which identifies something which we already 'half-believe'. All Parmenides is doing is rigorously (so he believes) following through the logical consequences of that belief.

All the best,