To: Eleftherios A.
From: Geoffrey Klempner
Subject: Descartes' argument in the 6th Meditation
Date: 30 August 2005 10:10

Dear Eleftherios,

Thank you for your email of 20 August, with your second essay for the Philosophy of Mind program, in response to the question, 'Examine Descartes' argument, in the Sixth Meditation, for the distinction between mind and body. What objections can you conceive being raised against the argument? How would you attempt to defend the argument against those objections?'

The core of Descartes argument, as presented in the 6th Meditation is the principle that if it is possible to 'conceive clearly and distinctly one thing without another', then the two things must be separate substances, in the logical sense: even if the two substances are always found together, 'they can be placed in existence separately, at least by the omnipotence of God'.

This is what Descartes asserts to hold of 'my body' and 'myself as a thinking thing'. Is his argument valid?

Before I consider the objections which you raise, we have to look at the context of the argument: why does Descartes think that he can conceive of my body and my thinking self apart from one another?

It can't just be a matter of personal observation, because then an objector could simply say, 'Well, I can't conceive this!' End of argument. However, the clear and distinct ideas concerning mind and body are not simply given; they are the outcome of the argument which Descartes considers in Meditation 1, namely, the possibility that I as a thinking subject can exist in a universe where the only thing that exists apart from my mind is the evil demon who causes me to have illusory ideas of a material world.

If an objector says, 'How do you know that?' then all that Descartes can say is that the hypothesis makes sense, i.e. that he has a 'clear and distinct idea' of it.

The appeal to 'what an omnipotent God can separate' is merely used to underline the logic of identity and separateness. Descartes is not saying, 'my mind and body are separate because God can separate them'. That is not his argument. So far as the argument for mind-body dualism is concerned, God's existence is only required in the sense that the very possibility of philosophical argument depends on our being able to trust our powers of reason, which Descartes thinks is only possible if there is proof of a non-deceiving God.

Your first major objection is that 'if God created a miracle by separating body and mind, we wouldn’t be able to say anything about the relationship between mind and body in the real world for they are the result of a miracle'. It could be argued that this is precisely what Descartes believes. Mind-body interaction is miraculous, we can't explain it. We only know that it must occur. However, there is more to say on this, as we shall see below.

Your second major objection is partially met by the observation that Descartes offers an argument (the evil demon argument) for the separability of mind and body and does not merely rely on his intuition that they are separable. However, the objector is justified in replying that the same objection applies to the evil demon thought experiment. The thought experiment seems to be coherent, we seem to have a 'clear and distinct' idea of it, but we could be wrong. This is what contemporary critics of Descartes would say.

As a matter of interest, there was a popular view in the 60's which originated with the 'Australian materialists' Armstrong and Smart, which attempted to side-step the question whether mind can exist apart from body, and asserted that, from a scientific point of view, the best explanation of our experience is a 'contingent identity' between mind and body: in other words, granting the evil demon possibility, but rejecting the claim that this shows that mind and body are not, as a matter of contingent fact, identical. In 'Naming and Necessity' (Blackwell) Saul Kripke demolished this view with a brilliant argument, vindicating Descartes' claim that *if* mind and body can exist separately (i.e. if the exist separately in some possible world or worlds) then they cannot 'in fact' be identical.

Following on from your first major objection you consider the difficulty in maintaining the view that there exists an organ (the conarium or 'pineal gland') where mind and body interact. I agree with your objection here. However, it is worth pointing out that Cartesian physics differs crucially from Newtonian mechanics in allowing for the change of direction of 'animal spirits' without any input of energy. This is because Cartesian physics is based purely on the analysis of geometrical extension - a feature which Leibniz heavily criticized on the grounds that it failed to account for 'force' and 'impenetrability'.

Do the alleged facts of parapsychology go any way towards mitigating the objections to Descartes' argument? I think we would have to say that if telepathy, or telekinesis, or out of body phenomena were conclusively verified in a laboratory, then this shows that there is something we do not understand about the workings of the physical world, i.e. particles or forces which have up to now escaped physical observation. I would not be a vindication of Descartes view that mind and body are logically distinct substances.

All the best,

Geoffrey