To: Sara R.
From: Geoffrey Klempner
Subject: Personal identity and the body duplication hypothesis
Date: 23rd March 2011 10:49

Dear Sara,

Thank you for your email of 15 March, with your second essay for Possible World Machine, in response to the question, 'Imagine you are Michael Harding. As you lie injured on the road, you are told that a brain scanner is going to be used to map your memories and personality, and the information used to programme the brain of a new body cloned from of your own cells. The moment the new 'you' gains consciousness, the old 'you' will be painlessly destroyed. How do you feel about that prospect? Justify your answer by reference to one of the competing philosophical accounts of the relation between mind and body.'

I am interested in your response to this question: 'I do not subscribe to a materialist view of mind... to quote Nagel, 'physicalism is a position we cannot understand because we do not at present have any conception of how it might be true...'.'

As you have stated several times, you are not religious, so I assume that you do not believe in a Cartesian 'soul' -- or do you? Or is there some other less committed dualism that you have in mind (e.g. epiphenomenalism)?

Rather than launch into a debate about 'isms' let's look at some possible ramifications of the Mike Harding thought experiment. Let's say you wake up in a hospital bed, with horrific memories of the accident. You are glad that you survived. As your health progresses, you finish the philosophy essay on personal identity which you were thinking about when the accident happened. In your essay, you state the things you have stated here:

'Even if my brain neurons were replicated, and my memories fully restored, there could be no way that my clone could *interpret* those memories and experiences (qualia). It might remember facts, for instance where I lived or that I liked a certain piece of music, even why I liked it, but how it actually felt to me whilst experiencing that home or piece of music would remain elusive and the clone would have to build up new meanings.'

THEN you learn the awful truth. You are Mike Harding's clone, not Mike Harding.

There are at least two possible responses at this point. The first is to dig in and refuse to accept, point blank, that what I have just described is a possible experience. You just KNOW that you could never be wrong about whether you are Mike Harding or Mike Harding's clone. How do you know this? Bear in mind that the question, 'How do you know?' is one of the most basic moves in philosophy. 'I just know' isn't an adequate answer.

A second response would be to refuse to accept (again point blank) that body duplication as described in the thought experiment is, in fact, possible. It doesn't follow (as I would argue) that if you assume the truth of materialism, then it must be possible, in principle (however broadly this is interpreted) to 'duplicate' a living human being. I wrote something about this a while ago, 'Truth and subjective knowledge' (http://klempner.freeshell.org/articles/shap.html) where I argued that, 'there is a very real sense in which knowledge of my subjective experiences is available to me in a way that it is impossible in principle to communicate to others. Not because my subjective experiences are private objects in the sense attacked by Wittgenstein. But because the only adequate way to access what is in a brain, is to be the owner of that brain.'

In other words, you can be a materialist and refuse to accept that the brain is like a computer running a 'program' (which could in principle be reproduced in 1s and 0s on a sheet of paper). Subjective knowledge is 'encrypted' in the brain in a way which makes it impossible to 'read' by anyone except the owner of that brain. The point here (the finesse) is that we don't know whether this is true or not. It is not necessary to make any dogmatic claim, because we have effectively shifted the onus onto the person who put forward the thought experiment in the first place.

That's still not fully adequate as a response, however. The move gives you the chance to avoid embracing dualism (concerning which I would echo what Nagel says about materialism, we have no coherent conception of how dualism might be true). But it still leaves open the possibility that critics of the AI approach such as John Searle are wrong, and that the brain does indeed 'run a program', in which case, what we term 'persons' would become endlessly replicable, like copies of Microsoft Word.

All the best,

Geoffrey