To Matthew M.
From: Geoffrey Klempner
Subject: Parmenides on the unthinkability of 'what is not'
Date: 29th October 2010 12:14

Dear Matthew,

Thank you for your email of 23 October, with your essay for the University of London BA Greek Philosophy: Presocratics and Plato module in response to the question, 'How important to Parmenides is his claim that "What is not" cannot be thought?'

You have had a good go at what seems to me a rather confusing question. There are various questions one could ask about Parmenides' One or 'What Is': What he means by 'is' (existence, predication, truth), the deductions which he draws from the premise 'It Is' (Reality has no past or future, no differentiation, is limited 'like a sphere' and so on).

You cover these in your essay; you also raise the very good question what Parmenides means by 'thought' or 'thinking': Does he have in mind a special kind of non-empirical thought, the thought that a God might think? You also make a good point about his use of 'not'. Surely, it cannot be that the very idea of negation is impossible, or in that case he could not coherently make the statement, 'What is not can not be thought.'

There is also a suggestion in your essay, which I would have liked to have seen expanded upon, that Parmenides was developing a critique of a particular way of thinking of 'what is not', as it were the reification of 'the not' as, e.g. the 'nothing' that (according to a certain naive way of thinking) separates one discrete object from another, or the idea of the universe coming into existence from a previous state of sheer non-being or non-existence, or indeed the idea that negation is a property alongside other properties (so that, e.g. in not being green, my table has the property of being brown and also the property of not-ness).

It would be nice if we could re-interpret Parmenides in this way, as offering critique of notions which undoubtedly deserve critique. That would rehabilitate his reputation in the eyes of contemporary philosophers. I have even come across an interpretation according to which 'what is' refers simply to 'the facts' or the 'totality of facts': as in the Tractatus, 'the world is all that is the case... facts in logical space' -- a space which is necessary filled and does not contain any gaps.

But this is taking us way off track.

What the question seems to be asking concerns Parmenides' motivations. The fact that some of the things he says -- applying the principle of charity -- could be interpreted in a way which makes him a lot more interesting in the eyes of contemporary philosophers is irrelevant.

I think that something you don't mention is relevant here. It does not seem implausible to see Parmenides as *reacting* to the nascent philosophical tradition, in particular the theories of the Milesians. All the talk about the Goddess, his seemingly half-hearted (but very thorough) pseudo-Milesian theory of 'light' and 'night' in the Way of Opinion, suggests that he is focusing on an idea in which he very much believes: the idea that there is a difference between appearance and reality, between how things present themselves to our senses and how reality presents itself to pure thought.

For Anaximenes, to take an example, the senses present a variety of kinds of substance arranged in various ways; what thinking discovers, by contrast, is one substance, air, all of whose modifications can be explained by a single process, condensation and rarefaction. In Parmenides' eyes, this is interesting but it is not fundamental. The theory arises out of thinking -- or more accurately speculating -- about the nature of reality, but it is still tied to the world of our senses.

Parmenides mind-blowing revelation is that thought alone, without any need to speculate or guess the ultimate nature of things, can determine how things really are in every relevant detail. It is logic alone which determines the nature of reality. What he is saying to the Milesians, effectively, is 'You can carry on doing what you do: here is my theory (the Way of opinion) to add to the debate. But you're missing something more fundamental.'

Note that I am not arguing the 'the One' is specifically intended to be the One of Milesian cosmology (which is an interpretation which has been offered alongside the other interpretations of the meaning of 'is'). If 'is' was intended to refer to the Milesian One, Parmenides' argument would be merely ad hominem. Whereas he is starting from the very basics, not assuming anything.

In that case, the answer to the question would be: What Parmenides means by thought is not thinking as a psychological phenomenon but rather as a logical notion. So that 'X cannot be thought' is equivalent to 'X is logically incoherent' or 'X is logically impossible'. The reason that the claim that 'What is not' cannot be thought is important, is that without any further premisses Parmenides is able, he thinks, to deduce the nature of reality, in all its logical features.

All the best,

Geoffrey