To: Egor S.
From: Geoffrey Klempner
Subject: Descartes' arguments for the existence of God
Date: 3rd May 2011 12:57

Dear Egor,

Thank you for your email of 27 April, with your essay for the University of London BA Modern Philosophy: Descartes, Locke, Berkeley and Hume module in response to the question, 'Explain the strengths and weaknesses of Descartes' arguments for the existence of God'.

The most remarkable thing about this essay is that you offer no less than FIVE arguments for the existence of God which you attribute to Descartes -- God as origin of knowledge, God as cause of myself, innateness of the idea of God, God's existence as a necessary attribute of a perfect being, God as the guarantor of truth -- while I always thought that Descartes has essentially TWO arguments, the argument from the idea of infinity and the ontological argument!

However, I understand what you are doing here. There is a distinction between arguments deliberately put forward and flagged as 'arguments for God's existence' and arguments which can be extracted from the text, with a certain degree of charitable interpretation.

I think you need to state this, and support your claim with clear references. (To be fair, you do offer some references to Meditations, not not in support of each of the five arguments you attribute to Descartes.)

What would be proof of the existence of God? In Meditation 1 Descartes considers the possibility that all his experience is caused by an 'evil demon' who is far more powerful than he is. Clearly, it would not be sufficient to argue for the existence of 'some being more powerful than I' if this description is satisfied by the evil demon. That is not an argument for the existence of God. Nor is it what Descartes clearly wants: to prove that the ultimate source of his being and his experiences, is wholly benign, not deceiving, all powerful and not just very powerful.

But let's look at each of the arguments in turn:

God as origin of knowledge

My knowledge must come from somewhere. Maybe it comes from the evil demon? In that case it isn't 'knowledge' but merely a deceptive, albeit coherent dream. But that was the very thing that Descartes sets out to disprove! Why must the origin of knowledge be God?

The reply would be, 'Where does the evil demon's knowledge come from?' This is your point about the infinite (vicious) regress. There must be something concerning which we do not need to ask, 'Where it's knowledge comes from' because its very nature is such that it does not depend on some other being, i.e. God.

Does Descartes say this? where? This is an example where you must give a reference back up your claim. I don't think you can extract this from the formal reality/ objective reality distinction.

Leaving that aside, how good is the argument? Whereas there is no doubt that there IS motion, Descartes himself has raised the question whether there is any knowledge. I can see an argument to the effect that if there is knowledge then God must exist, as any other source of our experiences would not have sufficient reliability to count as a source of knowledge.

Arguably, the theory of evolution does offer an explanation of why we are beings naturally constituted to be capable of gaining knowledge necessary for our survival. This is a point made by contemporary innatists such as Peter Carruthers -- that you can be a good empiricist yet claim that our sense of what constitutes the 'best explanation' is in some sense innate.

God as cause of myself

Once again, the evil demon could have created me? Why not? The point about perfection is that, armed with the idea of different 'degrees' of perfection (as you state, based on observation of beings less perfect than me) I can conceive of something with greater perfection. But this could still be the evil demon. Only something infinitely perfect satisfies the requirements for being God.

However, I actually think that the idea of 'God as cause of myself' is very powerful as an incentive to belief (I state this as an atheist). In my book 'Naive Metaphysics' I argue that an all-knowing God cannot know one thing: that *I* exist -- because from God's perspective there is no difference between my existence and GK's existence. That I am GK (cf. Thomas Nagel's 'I am TN' in 'The View From Nowhere') is something God can never know.

But I can see how this argument could also be turned around. No scientific account (such as the Big Bang theory) could ever explain why *I* exist. At most, it can only explain why GK exists. I don't know how God could create I (given what I said in the previous paragraph!) but no natural cause would be adequate either, so it must be a 'non-natural' cause, such as God is meant to be, even though I cannot comprehend how this is possible.

Innateness of the idea of God

This is more recognizably Descartes' 'argument from the idea of infinity'. I accept that there is 'circular reasoning' in the claim that I HAVE the idea of infinity. This is a big question in philosophy, especially philosophy of mathematics. Do we have this idea? You can define an infinite set in terms of '1-1 correspondence with a proper subset' but this reduces the notion of the infinite to a kind of rule (such as the rule for constructing the series of natural numbers, 'plus 1').

The 20th century continental philosopher, Emmanuel Levinas, in his great opus 'Totality and Infinity' makes a comparison between Descartes' argument from the idea of infinity and our idea of the Other, as something that goes beyond 'totalizing' knowledge. This is part of his project of constructing an 'ethical' basis for metaphysics in the existence of the Other -- a kind of parallel to Descartes' case for God.

I only mention this because I do feel that Descartes has latched onto a very powerful idea, even though, finally, I am not convinced.

God's existence as a necessary attribute of a perfect being

This is the ontological argument. I think that this argument can be given a better run for its money than you give it. In contemporary discussions the key feature emphasized is the possibility of God. What the ontological argument effectively claims is that if the notion of God is conceivable -- if it does not entail any logical contradiction, or if God exists in some possible world -- then God must exist in all possible worlds. In other words, it puts the onus on the disbeliever to prove that God does not exist in any possible world, i.e. that the very notion of God as defined is incoherent and contradictory.

God as the guarantor of truth

As with the first argument which you describe -- the argument from knowledge -- there is clearly a worry about begging the question. What Descartes is setting out to establish is that there is such a thing as knowledge, that it is possible to distinguish truth from falsity. Maybe I am being deceived by an evil demon in which case there is no knowledge and no truth.

However, this is an argument I have seen deployed by a contemporary philosopher: Michael Dummett, who is well known as an expositor of Frege and who has also put forward some very challenging arguments for an 'anti-realist theory of meaning' where the notion of truth is replaced by verifiability, has expressed the view that this could be the basis of a Berkeley-style argument for the existence of God, if we find the Protagorean consequences of an anti-realist view of truth repellant.

All the best,

Geoffrey