Imagine the following situation:
A woman, let’s call her Su, is hit on the head and her memory and personality are destroyed. Over the course of several years, she acquires new memories and a new personality as her brain heals and she is trained back up to adult-levels of competence in most skills. Notably, all of this actually happened, so so far we’re not in a science-fictional thought experiment.
Choice 1: first person
Now, imagine (and this part has never, to the best of my knowledge occurred) a surgeon tells the woman and her family that he can finally “heal” her. She will have all of her memories and personality restored, but it will:
Scenario A: wipe out her current memories and personality, so she (or whoever) will awake exactly as before the accident, but thinking no time has passed.
Scenario B: wipe out her current personality, but not her current memories. When she (or whoever) wakes up, there’ll be an odd recognition of acting quite strangely for many years, and a sense of being restored, but no gap in time. However, the person who awakes will have trouble recognizing herself in her actions, emotions, and responses in the time since the accident.
Would Su, at being told about the surgery, want it? I would guess she would refuse (we could, of course, ask the real Su, but the question is not so much what Su would do as what people in general are likely to choose.) In the U.S. there are strong rights to refuse medical treatment, so there’s no ethical problem here. It seems mostly likely that she would refuse Scenario A, and, based on personal identity x-Phi work like that of Nichols and Strohminger, also very likely that she would refuse scenario B. I would think that people would think of themselves as destroyed in both A and B.
Choice 2: third person
Now, imagine, instead, that after acquiring the new memories and personality, Su is again struck on the head. She is in a coma, and a surgeon comes and tells her family that they have 2 choices:
- he can do a surgery which will enact either scenario A, or,
- he can do a surgery which will restore her to how she was immediately before the most recent blow to the head.
Does the family have a right to choose 1, destroying NewSu?
Suppose the surgeon also offered them
- that he can do a surgery which will enact scenario B
Is this the moral choice? Is it any better, from NewSu’s perspective, than 1?
It seems that in 1 and 3, NewSu is destroyed. However, Su is resurrected. It seems like this might be a moral toss-up for that reason. But in the most similar cases, there is a clear ethical solution:
There is almost no scenario in which a third party can decide that you should be sacrificed so that someone else might live. If that’s what’s happening, then the family cannot rightly choose 1 or 3. Of course, this relies on us as thinking of NewSu as the currently existing Su. But maybe she’s just the most recent Su, or the most recent manifestation of Su, if you want to unify them, or some such. In that case, then again there’s no clear answer.
But: if the surgeon told them that NewSu would wake up on her own in about 6 months, as the brain healed, or, he could do the surgery, but it would restore OldSu, then the choice is perhaps clearer. As much as the family might want OldSu back, then seem to be intervening in a way that kills NewSu.
Or perhaps in a case like this we have no real moral guidance, as our identity and rights concepts are not prepared for the case. But that alone tells us something about the (lack of) robustness and universality of those concepts, especially the identity concept.
 See I Forgot to Remember by Su Meck for the full story.