Lee: >>Not quite! It turns out that everyone who knows them regards >identical >>twins as different persons. And so regards them, I am pretty >certain as >>different people in a way that they were *NOT* so regard you and your >>duplicate. You and your duplicate---created yesterday, >say---would be >>SO SIMILAR I claim, that people would regard you as the same person. >>It seems that identical twins always do have slightly different >>personalities, and that a lot of the differences they exhibit were >>created during the nine months before birth. >> >> > > Of course, if you can't affect it, that's a reason for >> > > non-concern. >> > > But if you could, then, I contend, one intervenes to >prevent one's >> > > duplicate from suffering for entirely *selfish* reasons. > >Stathis: >It seems that we are just defining the term "me" differently. >My definition is that if you stick a pin in a person and I >feel it, then that person is me. If you stick a pin in the guy >across the room who looks, talks, behaves etc. like me, *I* >don't feel anything. Isn't this a rather basic, scientifically >verifiable difference? > >You may also have something different in mind to me when using >the term "selfish". In evolutionary biology, animals sometimes >engage in apparently self-sacrificing behaviour to help their >kin, but in reality the behaviour is "selfish", because in so >acting the animal is propagating its own genes (which is >basically all nature cares about). In this sense, you could >argue that we should behave altruistically towards those who >share our genes, and call this "selfish". I don't accept this, >generally, as an argument: just because it is nature's way >doesn't mean it is right. But even if i did accept it, it >*still* isn't the same when my copy gets stuck with a pin as >when I get stuck with a pin. I might feel guilty about it, but >I would prefer that he get stuck ten times rather than that I >get stuck once.
That raises an interesting question. *Should* we (whether reasoned on an ethical basis or a purely selfish one) care more about a copy of ourselves getting hurt than a complete stranger? I have little doubt that I *would* rather a stranger get stuck than my copy, but only, I think, because I would have more empathy for my copy than for a stranger, in the same way that I would have more empathy for my mother getting stuck than I would for someone I don't know. Beyond the empathetic rationale, I don't see any convincing argument for favoring the copy over a stranger. The copy is not, after all, *me* (although it once was). We ceased being the same person the moment we were copied and started diverging. Jonathan Colvin