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Strawson: impossibility of individuating Cartesian soul


To: Matthew M.
From: Geoffrey Klempner
Subject: Strawson: impossibility of individuating Cartesian soul
Date: 13th April 2010 11:08

Dear Matthew,

Thank you for your email of 2 April, with your essay for the University of London Diploma Introduction to Philosophy module, in response to the question, 'Strawson states the principle, 'If we are to talk coherently about individual consciousnesses or minds we must know the difference between one such item and two such items'. Is this principle correct? Does it create a problem for Descartes’ account of the mind?'

In your email you expressed the worry that you have not covered 'all the work for the exams'. Remember that you only need to answer three questions from the exam paper. A good strategy is to make sure that you are fully prepared to write about the topics you have covered, and also have one or two backup topics which you could write on at a stretch, if you were unlucky with the choice of exam questions.

This is a good essay, well set out and confidently argued. An examiner would give you credit for attempting to 'think out of the box' and bringing in Heidegger's view on Dasein, although as you yourself admit, this doesn't really help the Cartesian.

There are two points where I think that your argument could have benefited from greater clarity. The first point is where you consider the second of Strawson's arguments against the Cartesian soul, which you term 'the identity issue'. You could have added here a similar hypothesis to the '100 minds all having the same thoughts'. This would be the hypothesis that (e.g.) as I write these words my Cartesian soul is destroyed every second and a new soul created with all my former memories. This is, in fact, a thought experiment which Kant considers in the Critique of Pure Reason, in the grandly titled 'Paralogisms of Transcendental Psychology'.

The point, as before, is that there is 'no difference' between the hypothesis of a persisting soul, or the hypothesis of a continually destroyed and created soul.

Of course, you can ask, in both cases, exactly what the 'no difference' claim amounts to. Is it just an expression of the 'verification principle', according to which a proposition is meaningless if it cannot be empirically verified? In which case, it would be vulnerable to objections to the verification principle. I would defend Strawson on the grounds that this is not about the verification principle, but rather about a fundamental logical requirement for intelligibility.

The essay title does ask you to state whether you think this principle is correct. One can think of counterexamples, like clouds, where you can talk of individual clouds in the sky, even though it is sometimes difficult to tell where one cloud ends and another begins. I think Strawson would respond that this is a marginal issue, unlike the case of Cartesian souls where the problem is not one of vagueness in drawing the boundary line between one entity and another entity of the same sort.

Another thought, which goes in a completely different direction, would be along the lines of, Why do we have to assume that a person is a soul together with a body which is located in space? In Leibniz's theory of monads, 'space' is just a construction. What is real are the individual monads each of which represents the entire universe from a unique point of view. As a consequence of Leibniz's theory, there cannot be two monads with identical states of consciousness, because then they would be the same monad. In his book 'Individuals' Strawson argues against the monad theory, on the grounds that it fails to provide adequate criteria for individuation, but the argument is less convincing, because he has assumed from the start that we describing a situation in which a 'speaker' identifies and re-identifies objects for a 'hearer'.

You go on to ask how Descartes arrived at his notion of a soul or 'thinking non-extended substance'. This is a good move. However, I think you miss something here, and this is the second point where you needed more clarity.

You say, 'It seems that although Descartes and Strawson both argue logically they start from different positions.' The implication seems to be that this is something of a paradox. But is Descartes' argument from the possibility of an evil demon logically watertight, as you seem to suggest? Surely, a critic could point out that if he is being genuinely sceptical, then Descartes has no right to conclude that an evil demon cannot deceive him into thinking that he has, e.g. existed one second ago, or that there are 100 Cartesian souls all thinking that they cannot be deceived by an evil demon!

Taking this into consideration, Strawson's argument does seem stronger. It trumps Descartes' sceptical considerations because it uses Descartes own sceptical strategy against his own theory of an immaterial soul.

All the best,