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Descartes' proof of God in the Third Meditation


To: Stuart B.
From: Geoffrey Klempner
Subject: Descartes' proof of God in the Third Meditation
Date: 3rd October 2008

Dear Stuart,

Thank you for your email of 25 September with your University of London Modern Philosophy essay in response to the question, 'Descartes' attempt to prove the existence of God in Meditation III is not merely a failure, it is a philosophically uninteresting failure.' Discuss.'

By pure coincidence, I have just sent off a reply to the first essay submitted by one of my new UoL Diploma students, in response to the Introduction to Philosophy question, 'By what means does Descartes attempt to show that there is reason to doubt everything one believes?' Most of the students who have attempted this question miss a vital step in Descartes' argument and this was no exception. Descartes considers that he is made by a God, and the terrifying prospect that God is deliberately deceiving him. Then he considers the alternative: that he is just the product of adventitious causes, that he came into existence for no reason at all. In that case, Descartes remarks, there is all the more reason for doubt.

I mention this because the Theory of Evolution by natural selection plays a major part in your response to the question about Descartes' proof of the existence of God in Meditation III. The answer to the question raised in Meditation I, which of course Descartes is not in a position to give, is that there can be a naturalistic explanation of how our cognitive apparatus comes to be 'designed' to be fit for acquiring knowledge. The concept of knowledge has an ineliminably teleological component. That teleology must come from somewhere, there must be some explanation of how it is that the normal functioning of our cognitive apparatus leads to reliable knowledge, otherwise scepticism is the only reasonable conclusion.

I find it a bit strange, therefore, that you (following Dennett) focus on the point about Evolution in your explanation of where Descartes goes wrong in Meditation III.

What is this idea of 'God' which Descartes has? It isn't just the idea of 'supreme intelligence' or 'great intricacy'. To think that this is all Descartes is impressed by is to miss the point entirely. Suppose Douglas Adams is right and we were created by intelligent mice. Or at least assume that being a somewhat misguided reader of Adams, I have come to believe this. That is a pretty amazing hypothesis, all the more so when one attempts to fill in the details of how this would be done in practice, the technology that this would involve. Where on earth does this idea come from?

Well, we're here, aren't we? In the absence of a theory of evolution, we can still do science. We can still investigate and wonder at the amazingly intricate beings that we are. But 'the fact that such an idea was to be found in the mind would be something aching for explanation' is no more aching for explanation than the plain fact that we are here. We are sufficiently intricate, and the world around is sufficiently intricate, to provide us with more than enough materials to dream up supremely intelligent mice -- or whatever.

This argument would not impress Descartes. He isn't interested in anything as mundane as mice or supermen or anything which is merely 'bigger and better' than we are. He is struck dumb by the realization that he has, within himself, a concept of infinity. God is not just a lot bigger than us, he is infinitely bigger. He is not just more perfect, he is infinitely perfect.

It is indeed a good question to ask whether, finite beings as we are, we are capable of forming a concept of infinity. I'm not talking merely of the mathematical formula, but rather the idea that there might exist, in actual reality, something of infinite extent. At least, it is a proper subject for philosophical debate. (See the excellent book by A.W. Moore 'The Infinite' RKP.)

A radical take on this move by Descartes can be found in the work of the (admittedly difficult and obscure) philosopher Emmanuel Levinas, who links Descartes' argument over the idea of infinity with his own philosophy of the 'otherness of the Other', the idea that the very conception of there being 'someone else besides me' takes us beyond merely empirical knowledge into the realms of the metaphysical (which leads Levinas to argue that ethics -- recognition of the Other and what that entails -- is the basis for metaphysics rather than the other way round.)

Be that as it may, I think that Dennett (for once) has completely missed the point here (at least, on the basis of your report of Dennett's argument as I haven't seen the original). I would argue that Descartes' failure is a philosophically interesting failure because the problem of infinity is one that we are still grappling with today, even if we are more inclined these days to drop the 'God' connection.

All the best,