http://alexanderpruss.blogspot.ca/search/label/Parfit
A few relevant paragraphs:
This is true even if I foresee that my character will shift in significant ways over the next 20 years, that I will then not have many memories of how things are for me now, and so on. In other words, I have the right to sacrifice the life of my future self for a stranger even if my future self will not be very much psychologically connected to me. On the other hand, I have no right to sacrifice the life of my friend for a stranger without my friend's permission, and the closer the friend is to me, the worse such a sacrifice would be. This shows that my relationship to my future selves is significantly unlike my relationship to my friends. It does not matter how psychologically close to or distant from my future self I am--I have the right to make the sacrifice. But the closer I am to my friend, the worse it is to sacrifice the friend for a stranger without the friend's permission.
Thus, sometimes, identity matters, and psychological connectedness is largely irrelevant. Could one replace identity with psychological continuity in these considerations? No. For suppose that I know that next week I will fission into two individuals. I will have psychological connectedness and continuity with them. But I have no right to sacrifice their lives to save the lives of two strangers, e.g., by exposing myself now to a dose of radiation that will result in the two descendant individuals dying in two weeks. It would be like sacrificing the lives of two children of one's own to save two strangers. The psychological connectedness and continuity are insufficient for permissibility here. And even if it were permissible, it would hardly be praiseworthy.
