To: Emily P.
From: Geoffrey Klempner
Subject: Hume on the self and personal identity
Date: 7 January 2005 12:04

Dear Emily,

Thank you for your essay dated 13 December for the Possible World Machine units 1-3 in response to the question, 'The philosopher Hume remarked that when he looked into himself, he never succeeded in catching sight of his 'self', but only of particular thoughts, feelings and perceptions. Is that a valid argument against the idea of a soul?'

I am sorry for the delay in my response. I only picked up your essay earlier this week.

This is a very good piece of work. There is clear evidence that you have thought this question through for yourself, rather than just reproducing arguments from the Pathways unit or from other reading that you have done.

You put forward several arguments: 1. it is not surprising that Hume cannot see his soul, because something which is a part of a process or a chain is not able to gain a perspective on the sequence as a whole. 2. it does not follow from the fact that Hume is unable to catch sight of his soul, that anyone who attempts this will also fail to catch sight of his or her soul. 3. what gives the soul its identity might be an unknown substance or entity underlying the mental events which we are able to observe. On the other hand (4), if the soul really is separate from the body how do the two interact? 5. It is hard to look for something when you don't know what you are looking for.

If a tree could think and perceive, there would be nothing to stop it investigating the process of which it forms a part, and grasping that process as a whole. So this looks at first a rather unconvincing example. Or suppose I look down at my body. There are various parts I can't see, however athletic I may be. Yet, there is nothing to stop me using a mirror.

However, I can see what you are driving at. Whatever it is that gives unity to my thoughts, feelings and perceptions cannot be anything inwardly perceived, because anything perceived is just another part of the whole, not the whole as such. Kant had a similar idea when he argued that ever mental act presupposes the 'transcendental unity of apperception', or the 'I think' which 'accompanies each perception'. This unity is 'a priori' or prior to experience because it is logically presupposed by the very act of being aware of an experience. Through an inevitable illusion, Kant argued, we are led to 'mistake' this unity of apperception for the perception of a 'unity', i.e. a 'soul substance'. So Kant both agrees and disagrees with Hume. There is no soul substance to be perceived, but there is a logical unity which accounts for my perceptions being 'mine'.

What would we say to someone who replied to Hume, 'Well I looked into myself earlier today, and I could see my soul perfectly clearly!' 'Describe it, then' might be one response. Hume is being ironic in giving the impression that he is merely reporting something about himself. He wants the reader to draw the conclusion that there is nothing that anyone can see by introspection that could measure up to the requirements for a soul.

The Cartesian dualist argues for the existence of a non-material soul from the 'indubitability' of my mental perceptions. Even if there was no matter, no world in space and time (e.g. if an evil demon is deceiving me) I would still know that I am aware of red now. So 'red now' cannot be identical with anything material. It seems rather strange, therefore, to claim that the soul is the unknowable cause of the mental items of which we are aware. I would still be aware of red now even if there is no evil demon, or any other kind of 'unknowable cause' of my red experience. Whereas Descartes gives the impression that he thinks that he is aware not only of the experience but also of the soul which experiences it - Hence Hume's sceptical response.

Still, it would be one possible response to Hume to say that the soul is neither material (for reasons which Descartes gives) nor mental (for reasons which Hume gives) but some third kind of 'substance' which is necessarily unknowable. This is close to Kant's view that behind the 'phenomenal' world there is a 'noumenal' reality of 'things in themselves' which lie beyond the limits of human knowledge.

The locus of mind-body interaction is a problem for the dualist. Something similar to Hume's argument can be used against anyone who claims that they 'know' the locus of interaction (e.g. the pineal gland, as Descartes believed). There is no way to identify the locus of interaction from the 'inside' or from the 'outside'. From the inside, all I see are thoughts, feelings and perceptions. From the outside, all I see are physical processes. There is no possible view or perspective which takes in both at one and the same time.

We don't know what we are looking for. That is your last point. Hume can be read as saying, 'If you think the soul is F, then it should be possible to perceive the soul. Therefore the soul cannot be F.' That does not refute the belief in the soul, but only the belief that the soul is F. The only way to refute belief in the soul using this method of argument would be to consider every possible thing the soul can be. And how would we know when we had done that?

All the best,

Geoffrey