The answer to this question depends on what one's criteria for personal identity are, as well as the nature of the changes in personality brought about by the envisioned brain manipulation. If, for example, one took personal identity to consist in psychological continuity, understood to consist in a continuation of interests, plans, projects, etc., then if one were to alter someone's brain and that person's personality were to change markedly enough that the person no longer shared the same interests, plans, projects with the person who entered the operating room, than the person would indeed have ceased to exist, as a result of the operation, and so one could be said to have effectively killed the old person in the operating room and caused a new person to be born. If, however, one takes identity to consist in bodily identity, then even in a case when a person's interests, plans, projects, etc., were to change markedly, provided that the person continued to occupy the same body, then the same person would persist. Now the deep question about personal identity, I think, is the extent to which one or the other or both criteria are relevant to identity. (Ought one to decide between the 'psychological criterion' of identity and the 'bodily criterion'? Is there a sense in which both criteria are relevant to identity?) I recommend anyone interested in the general topic of personal identity to read Marya Schechtman, The Constitution of Selves, a searching examination of literature on the topic of personal identity that elaborates a very plausible (and quite deep) position.
Some philosophers would say that there are 10 trillion and 1 (at least). After all, you are a person and none of your cells is a person, so you are a distinct thing from each of them, and so an additional thing to all of them. Other philosophers would say that "living thing" is not a count noun because "thing" is not a count noun, and you need to be more specific about what you are counting. Is it persons? Then there is one. Is it cells? Then there are 10 trillion. I am dissatisfied with both these responses. It seems to me that "thing" is as much a count noun as is "item" in a sign for a grocery line that says "Six Items or Less." And it seems to me wrong to think that strictly speaking one should be barred from taking a six-pack through the "Six Items or Less" line because it is seven items: one six-pack plus six cans. Instead, it seems to me that the six-pack just is the six cans (neglecting packaging), not something in addition. The very same portion of reality can be accurately counted two different ways: as one thing or as six things. In your example, there is something in the room that can accurately be counted as one living thing or as 10 trillion living things.
The prospect of going under anesthesia is a scary one, for all sorts of reasons. But I don't think you should have much cause to worry about identity issues. I have two comments that might help alleviate your concerns.
First, you might ask yourself: What would be the difference between its being you who wakes up from the anesthesia and its being a doppelganger with your memories? From the outside, you would seem exactly the same. And from the inside, it would seem the same too. Your doppelganger might be thinking something like this: "Yesterday I was worried about whether I would wake up from the anesthesia, and I'm glad that my worries were for naught -- here I am." In other words, the prospect that you're proposing is not really one that can be discerned -- either from the inside or from the outside -- as one that makes any difference to anything.
But if that doesn't help (and I'm a bit worried that it won't), it might better reassure you if you think about anesthesia on the analogy of sleep. I doubt that you think that the person who wakes up each morning is merely your doppelganger with your memories, so why should it be any different with anesthesia?
Good luck with your surgical procedure.
It sounds as though you are already making a break with your past (putting "I" in quotes suggests that you think of yourself as a different person, for when you describe yourself as you are now, you are not using quotes). You mention family and friends. Insofar as you have made vows of life-long partnership as a spouse and insofar as you have not renounced the duties of family life (one's obligations as a parent or child or sibling) it seems you do have some prima facie duty to "keep in touch" with that "I" or self whose life is bound up with theirs. This might involve not just increased visits, but more electronic and alternative means of communication so that they have more of an understanding of your current situation (send photographs of your appartment, favorite places in the new city, etc). Philosophers disagree about the extent to which friendships involve obligations of that sort. Some think of friendship as a gift, others may think of it as a gift as well but believe that once given and received, there are some duties that go along with it. These may be trivial (not breaking confidences) or substantial (going to their aid at considerable cost to yourself). However you stand on friendship and duty, I suspect that even calling someone your friend requires that you are actually interested in them (at best, you love them), such that if you are no longer interested in them, there may actually be no more friendship there. There may be one-way affection (they may love you) but without reciprocation, the friendship has ended. Ceterus paribus, I would urge you not to let these frienships end too easily. You have a good in older friendships (years of fidelity, love...) that is precious.
Yes, I think it is wrong to harm a benevolent and charitable person just because of what they did in the past when they held values that are different than what they currently hold. But we cannot run a legal system so as to avoid this wrong. Just imagine that juries, to convict, would have to find beyond a reasonable doubt that the accused has not had a change of values since he committed the crime in question. It would not be hard for many accused (and their lawyers and jury experts) to create such doubt. Many criminals would be acquitted and many of these would then commit further crimes. Others would be emboldened to commit crimes by the confident expectation that, if caught, they would find a way to plead a subsequent change of heart.
What I'm suggesting then is that our current practice of holding people responsible for their past conduct is the lesser evil. And we mitigate this evil in various ways: through statutes of limitation, through pardons, and through the occasional jury nullification (where a jury acquits even while its members understand that, on the basis of all the evidence, they ought to have convicted). Despite such mitigating measures, the wrong you are calling attention to is not entirely avoided or avoidable (much like the occasional conviction and punishment of innocent persons is practically unavoidable).
While the wrong is not, I think, reasonably avoidable in our criminal justice system, we can do better in our personal lives by being ready to forgive wholeheartedly in cases where a former offender really did have a change of heart.
The answer is NO.
Whatever incoherence there might be in wishing that *I* were just like David Beckham, this does not render it incoherent or irrational to desire or view as beneficial things which would, in effect, make one a different person.
Thus suppose that I wish that the person sitting in this chair one minute from now (and from then on) shall not be subject to any of the worries and temptations that distract me from what's important and that he shall otherwise be committed to the same ends as I am. Now would this person be me? That's an irrelevant question, because nothing about this topic was contained or implied in my wish. So my wish is perfectly coherent -- and also rational, I think, for my ends would be better promoted if my wish came true.
Now, of course, if your real end is that *you* should experience the positive reactions that many visit upon Beckham, then you better not wish for the person sitting in your chair a minute from now to be just like Beckham. For suppose you get what you wish for. Then whatever adulation would be bestowed upon that just-like-Beckham creature sitting in your chair would not be experienced by *you*, and so you sadly would not attain your real end.
Morale. A desire for a change that would make you a radically different person is incoherent only if (necessary condition) it also contains or implies the desire that this different person be you.
Even if this necessary condition is fulfilled, there may still be nothing incoherent about the desire -- for that different person may be you! Your wife's husband may be a different person a year from now not only by you being replaced by someone else, but also by your changing. For example, a year ago today, I resolved to lose my bad temper. More precisely, I desired that *I* would not get angry at people any more. I managed to live up to my resolution. So I've become a different person as far as my temper is concerned. But, on any non-eccentric account of personal identity, the person I am now is the person who made that resolution a year ago. I changed over the course of this past year -- I wasn't replaced by someone else. Since what actually happened is exactly what I desired, my desire wasn't incoherent. I desired that *I* should become a different (non-angry) person. I achieved what I desired, because the different (non-angry) person I've become is not so radically different as to be someone other than the person who made the resolution.
There is one very general reason and two more specific reasons that philosophers are interested in the question of whether consciousness is identical to a particular bodily state.
The general reason is this: we are interested in knowing what the most basic constituents of the world are, and how they are related. If consciousness is not identical to a bodily state, then wewant to know what sort of thing it is and how it seems to be able tointeract with the body. But if consciousness is identical to a particular pattern of brain waves, for example, then we are justified in thinking that mental states are not something different than physical states and consciousness can be understood through the study of the brain. In short, we want to clarify different categories of existence, eliminating the confusions that result from thinking that there are two (or more) things when there is just one, or thinking that that there is just one thing when there are actually two (or more).
A more specific, existential reason that we are interested in whether consciousness is identical to a bodily state concerns the possibility of life after death. If consciousness is identical to a particular bodily state, then it cannot continue after that bodily state ceases to exist. So those who think that there is life after death must reject the claim that consciousness is identical to a bodily state. (There are physical particles and forces that continue after the death of a particular body, of course, so if consciousness is identical to these particles and forces then it may continue after a particular body ceases to exist. Most identity theories, however, equate consciousness with a brain state.)
There is also a social or ethical reason for being interested in whether consciousness is identical with a physical state of the body. If there is such an identity, then anything that lacks the relevant physical state (a robot, an insect, a Martian, or a cloud of dust) also lacks consciousness, and needn't be treated as though it were conscious. On the other hand, if there is not such an identity, then there could be consciousness in many places we don't expect it to be, and an appropriate sort of humility is called for.
This is one of those cases where as long as we're clear on what we mean, there's not much of an issue. It would be perfectly in order to say "that creature existed two weeks ago; it was a chrysalis then." It's like saying that you existed lo so many years ago, though you were a toddler at that time. Leaving aside more radical doubts about identity over time, there's no problem with talking this way. If you say "that butterfly existed two weeks ago" and you mean something like "that creature, which is now a butterfly, existed two weeks ago" then there's nothing to worry about. But obviously if you mean "two weeks ago, this butterfly was around, as a butterfly," then you'd be saying something false.
There are more subtler issues that a philosopher might raise, having to do, for instance, with whether the butterfly (or you, for that matter) is present at any one moment (as opposed to being a 4-dimensional being whose time-slices are present at various instants). But that question would come up even if the butterfly had not, as it were, changed at all over the two weeks.
'We can only live in this "here and now" moment . . . in fact , there is no way we can ever live out of it . . . is it not?'
I am not sure what is supposed to meant by living in the present instant ("moment" I think has more to do with action). Living at an instant seems as impossible as living at some other time, because there isn't even time to draw breath in an instant. In any case I do not believe that there is something called "the present instant", so I don't see how we could live in it (at it?)
It (the present instant) is an abstraction, and it is not, in reality! I do believe there are present times, though, such as the present day or hour. The trouble with the instant is that it is not a time.
Individuation is the process of picking out individuals. We do this all the time in ordinary life. For example, if we were in a parking lot, we could individuate the cars in the lot. That is, from the group of objects in the lot, we could distinguish the individual cars. We wouldn’t have a difficult time figuring out, for example, whether there are five cars, or two cars or one car. We could distinguish each individual car. (Of course I haven’t said how we would do it, but it shouldn’t be hard to tell that story.) So there isn’t a problem of individuation for cars, at least in ordinary circumstances.
Your excellent question is how we individuate, that is distinguish, beliefs. Fred’s belief that the combined landmass of French Polynesia is roughly equivalent to the landmass of Rhode Island is a different belief from his belief that the total area (including the sea) of French Polynesia is roughly equivalent to the total area of Europe. Here we have individuated the beliefs by reference to the difference in the propositions which make up the content of the belief. But if we individuate beliefs by the propositions they are attitudes towards, it follows that beliefs about logically equivalent propositions are really the same belief. So Fred’s belief that if the boat sinks, everyone will drown, is the same belief as his belief that either the boat doesn’t sink, or everyone will drown. Contrast this with our car individuation task: Cars that look like separate cars really are separate. But here we have two beliefs that might, at least at first, appear to be separate beliefs, which, on this taxonomy, turn out to be different beliefs.
Some philosophers hold that mental states like belief are brain states. That is, they individuate beliefs such that if I’m in a particular brain state which, on their theory is the belief that p, then if we imagined a double of me on a twin-earth, who is physically identical to me, then, if he is in the same brain state, then he also has the belief that p. But some philosophers of mind, such as Hilary Putnam, and later Tyler Burge and others, have challenged this account, by arguing that two such individuals could have different beliefs, even while being in the same brain state. They conclude that we can’t individuate or taxonomize beliefs on the basis of brain states.
So to sum up: To individuate, we need a theory. We have a theory of what makes something a car, so we can distinguish cars in a parking lot. We’re less clear about what beliefs are, and different theories may individuate beliefs differently. If one theory of belief says there is one belief where another sees two, or two where another theory sees one, then those theories are in conflict, and the basis of taxonomy is still open.