Recently on the Extropy-chat email list there was (another) series of posts regarding the nature of selfhood/identity. This was begun by one correspondent as a challenge to other members of the list that their reticence regarding uploading and various other self-replication technology possibilities (eg some teleportation scenarios, etc) masked an underlying - unrecognised - belief in some kind of soul or self-essence.
The basic point being, that any argument which centred on an "it just wouldn't be me" claim is scientifically unsupportable.
The point of view which this correspondent is following is one which either A: denies any meaning to the words 'self' or 'identity' (regarding them as mere social fictions); or B: reduces these to a pattern of information or behaviour, either of which can be formally replicated from a material substrate other than the human body, and thus the same "self" will be present...
this substrate could be silicon (computer), machine, anything you like...the important thing is that if the precise set of information (memories/thoughts/behaviours) for a subject, say...Bruce Dickinson (why not?), are made to appear in something other than the original manifestation (Bruce's own original body and brain) then this new information-carrier will still *be* in any meaningful sense of the term, Bruce Dickinson.
The challenge then is this - if this is *not* any longer Bruce Dickinson, then what do we mean by these words? What in fact is the *self* of Bruce (or anyone else) which allows us to attribute identity to one manifestation of those thoughts and behaviours but not another?
There are several possible answers to this problem, and it is one hotly debated in philosophical circles at the moment.
I wish to deal with one particular angle which was present in the discussion on Ex-I. Why is it, the initial correspondent asked, that many people consciously commited to a materialist world-view still have an intrinsic hesitancy in allowing their sense of 'self' fluidity enough to include such uploaded versions? If there is no metaphysical essence or soul, then we must define identity in terms of thoughts, behaviour, memory. As one respondent put it, "the inescapable answer to the "but it's not me" objection is "well then, show us this me". It's just not possible; whatever you point at that might be you leads to absurdity". This is indeed the case. If we refuse anything non-material, then it must be something bodily which we are defining as the self. Yet (as Descartes argued all that time ago) the body can be almost entirely mutilated while still retaining this elusive 'self'-hood. Cybernetics theory has demonstrated the permeable boundaries of the individual to the extent that what we understand as 'self' in different contexts can include technological components (from a walking stick or a pacemaker to the computer through which we interact with other humans many miles away), while psychanalysis has succesfully allowed us to deconstruct the self into many separate and competing drives.
It has been argued that the defining element of self then is usually related to consciousness: it is the sense of self which most usefully confers selfhood. If there is no intrinsic link between 'me' as I sit writing this, and 'me' ten years ago, apart from the memories I have of being that person, then how would some other body (or even computer program) having the same memories and same capacity to think of itself as descending from that person ten years ago not also be me? How can this be a logically consistent position?
It should be noted that there is no real issue of transference of consciousness involved here (as some have been at pains to point out): consciousness itself does not get transferred, rather it gets split like a Y or a road which forks into two. Two bodies can then have the 'same' consciousness at the instant the copying process is completed, but will also instantly diverge as they have slightly different experiences etc. Because selfhood is not an essence there is not an issue of transferring the self - it can be precisely duplicated.
And yet still, to the dismay of the rational arguments' proponents, still many refuse to accept that another such upload could actually replace them or be a desirable future state.
It seems to me that it is not an anachronistic belief in a soul which prevents this acceptance, inherited in our subconsciouses from the religious heritage we have only recently begun to move beyond. The reason is rather a very subtle metaphysical implication present within our grammar, a grammar which is exposed both in our language and thought. People will not accept this because what we mean by the word 'me' can never refer to something outside of oneself. The word necessarily encompasses a sense of interiority. Anything which one can point to and say "that" cannot, logically, be "me". This is the only reason the acceptance of uploads etc is so problematic, and it's not because of a belief in some metaphysical self, it's because our conventions about the word and the concept of 'I' don't allow us to use it in reference to something oneself does not inhabit. The self that can be referred to in the third person is not the self, our grammar of thought doesn't work in that way.
It could be argued that we can think of a photograph or video as being 'me'. However there is a slight of hand in this process, for the image is only 'me' in a past sense; it is not the me, for precisely the reasons above. If pushed most people will see this and admit that in fact the photograph is not them, but a representation of the past-them. Just ask yourself, if that picture is 'you' then why does it not think or feel; why do you now not have access to its thought processes?
Of course, the flipside to this is that we do not have the same conventions regarding 'you', 'she' or 'he'. Therefore, it is perfectly permissible (and comprehensible) to say, "that (simulation) is her in exactly the same way that this (body) is her". This is because the second or third person is always necessarily external. We do not define others in terms of their internal states for we do not have access to these. The rationalist of course may argue that internal states are always describable in terms of externally available information (brain processes, etc). But to define something by this external information is to instantly remove it from the intrinsic definition of I-hood. It makes it an other by virtue of this very externality.
We can rationally think through our notion of self and work out why there is no essential difference between me and an exact copy of me; but the gut will always reject attempts to assign my selfhood to some other being.
A "that" can never be "me"...it will only ever be a that, he or she. (Or you).