To: James L.
From: Geoffrey Klempner
Subject: Strawson vs Descartes: 'no entity without identity'
Date: 18 November 2005 10:47

Dear Jim,

Thank you for your email of 12 November, with your University of London Diploma essay in response to the question, In his essay 'Self, Mind and Body', P. F. 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 acceptable? Does it make a problem for Descartes?

You give a clear and convincing account of Strawson's argument. So much so, that I was fully expecting that you would agree with his conclusion. But you do not.

Your strategy is known in Latin as 'tu quoque', 'you also'. Strawson has discovered a problem with specifying the identity conditions for Cartesian consciousnesses. However, if it is a problem as Strawson states, then the same difficulty arises with specifying the identity conditions for persons.

It would not be sufficient, however, to demonstrate that there is a problem with specifying the identity conditions for persons. Strawson's case against the Cartesian is not based merely on there being 'a problem' - a difficulty which provokes philosophical discussion and debate - but rather an out and out incoherence.

This is what you say:

'Simply stating that one person equals one mind does not defend against the possibility that there may be one thousand minds or souls within Professor X. How does he know that one person equals one mind? This is an assumption on Strawson’s part. He gives no evidence of his premise and has no means available to make the determination that one person equals one mind. There may be persons with several minds, possibly thousands, inside one person, all fighting to have its thoughts heard.'

- Well, Strawson would fully agree to this. Your hypothesis of 'several minds, possibly thousands, inside one person, [each] fighting to have its thoughts heard' is not the same hypothesis that Strawson considered when he put forward the example of Professor X. We are to understand that the thousand Cartesian consciousnesses each of whom knows itself as 'Professor X' all think *identical* thoughts. They cannot fight for control because there would be nothing to fight with. On the contrary, each continues in blissful ignorance of the others. Just as I am typing these words now: each of the thousand 'I's inside me thinks that *it* is typing these words. And it is perfectly right to think so.

Your later example of Plumber X and Professor X makes a similar point. There is such a thing as there being 'two persons with one body' (multiple personality disorder). This serves merely to confirm Strawson's argument: that in order to 'count' subjects we rely on the fact that those subjects are physically embodied. It would be absurd to claim that someone had multiple personalities, but that these could not be seen because the personalities were subjectively and behaviourally indistinguishable in every way.

In the Critique of Pure Reason (in the section named 'The Paralogisms of Transcendental Psychology'), Kant makes a similar point to Strawson, regarding the identity of a Cartesian consciousness over time. There is no logical difference, Kant claims, between the hypothesis that there is one consciousness 'inside' Professor X's body, and a series of consciousnesses each one of which lives only for a moment, then dies and communicates its state onto the next, like a line of colliding billiard balls.

In a part of Strawson's article which is not included in Guttenplan, I recall that he quotes the miracle of the Gadarene swine. A man who is possessed by devils has them 'cast out' by Jesus. The devils then invade a herd of swine. If devils are non-physical, how do you count them? Easy. By counting the number of swine which get possessed when the devils are exorcised. This is a graphic illustration of the point that Strawson is making: that our concept of 'a' subject of consciousness is logically tied to the notion of 'a' physical body.

I fully agree with you that there are serious difficulties with giving the identity conditions for persons, conceived as necessarily physically embodied. If you are interested in pursuing this further, 'Reasons and Persons' by Derek Parfit argues powerfully for the elimination of the concept of a 'person' using various thought experiments. Parfit draws some quite radical ethical conclusions from this claim.

Other philosophers, notably David Wiggins and Bernard Williams, have argued that the concept of 'personal identity' can and should be defended.

However, as I have indicated above, a problem for philosophers to discuss is not the same as an out and out incoherence.

All the best,

Geoffrey