To: Julian P.
From: Geoffrey Klempner
Subject: Locke on personal identity
Date: 19 April 2006 15:07

Dear Julian,

Thank you for your email of 13 April, with your University of London essay on Locke on Personal Identity.

What is Locke's view, exactly? Basically, with important reservations, Locke is a Cartesian. So his concept of matter is something like Descartes' 'extended substance'. No room here for the possibility that if you go deep enough down, this notion will be seen as based merely on experience, rather than a priori reasoning. The biggest step is simply to see the possibility that it is not a priori true, say, that the physical world conforms to Euclidean geometry. We have to investigate the world and see.

Your citation of the prince and the pauper story had me scuttling to Google. For some reason, I 'remembered' that the story as Locke gave it was that the souls of the prince and pauper are switched without any change in their consciousness.

In my paper, 'Is it rational to fear death?' I compare Locke's though experiments with Kant's Paralogisms of transcendental psychology. This is possibly the place where the seed of the misconception was sown:

http://klempner.freeshell.org/articles/fear.html

Anyway, this is an excellent essay, although I think there are some things you've missed.

Given that we don't literally have the 'same consciousness' in HAL's sense (an excellent example) because of gaps, false memories, etc. one would expect Locke to have a reply ready. This is the one given by personal identity theorists in elaborating the 'memory criterion', namely, that a unitary consciousness is the overall effect of a 'weave' of memories, just as you don't expect a single hair of cotton to persist from one end of a piece of cloth to the other. The problem with this, for the literal understanding of Locke's 'forensic' idea is that it leads to the consequence that I am and am not the same person, e.g. if I remember being the man who knocked the policeman's helmet off but not the man who mooned at the traffic warden.

I don't have a reference for this (you will find it in the articles in Perry Ed. 'Personal Identity') but the response to Butler is, or should be, that in addition to memory, in the sense of 'remembering x-ing' there has to be an identification, 'I was the one who x-ed'. This is the explanation of the Proust case, 'I clearly remember the affair but *I* was not the one who loved her.' There's a technical term for this kind of 'memory' - I'll call it schmemory. In order to be guilty of the crime, I must not only schremember doing it, I must also remember. Myra Hindley always claimed that, after her long years in prison, 'she' was no longer the person who 'remembered' with horror (she only 'schremembered') the cries of the Moors victims.

You quote Leibniz's criticisms of Locke's use of the soul approvingly but I'm not convinced. Souls can exist in the absence of material things, this is the essence of Descartes argument for the view that souls are essentially non-material. Descartes might well have believed that you can't switch souls without changing identities but Locke is sceptical. We don't know anything about souls or what they can do. At most we only know what souls are not (matter).

You quote from Leibniz an argument that GK on doppelganger Earth would be me on Locke's view. There are two possibilities to consider, however. The first possibility is that, as a matter of a cosmic fluke, there just happens to be a world just like this one somewhere in the universe with someone just like me writing to someone just like you. However, there remains the logical possibility - even if determinism has held up to now - that at some point in the future the two worlds will diverge. Or, to make this clearer, imagine two different worlds which, again by a cosmic accident, are indistinguishable for just one second then diverge again.

The second possibility is more like Nietzsche's eternal recurrence - except that the endless worlds are lined up in space rather than in time - where as a matter of logical necessity the two worlds are the same at every point. Here, by contrast with the former case, it does seem to make sense to hold that as 'I' type these keys, 'I' am simultaneously typing the same keys in all the other worlds.

However, this idea assumes a Leibnizian pre-established harmony as the explanation for the relation between soul, and its states of consciousness and body. On the interactionist view, we have to trace the causal sequence. My thinking about what to type next causes these key taps, and not the key taps on the doppelganger world. Locke would have said, with Descartes, that my conscious decisions cause the movements of my body.

The biggest omission in your essay is a discussion of the question of the causal basis for memory (there is an excellent account of this in David Wiggins book 'Sameness and Substance'). There has to be more to genuine memory than mere correspondence of my memory with the remembered event. This for Wiggins is the spatio-temporal continuity, in an organized package, of the physical basis for memory. On the soul view (if one could, per impossibile make sense of this at all) it would require having the same soul. Just because I 'remember' doing what Hitler did doesn't make me Hitler unless my memory not only corresponds to but is 'caused' (in the right way) by the events I remember. This is consistent with Kant's thought experiment in the Paralogisms of a sequence of souls each communicating its state to the next.

The causal basis idea does not, however, remove the possibility of branching, which produces two equally valid candidates for 'same person'. Locke should say that if Hitler was put into a person-duplicating machine we should punish both the individuals that come out. You can still save the logic of personal identity in these cases, at a price.

All the best,

Geoffrey