From the dawn of civilization humans believed in eternal life. The flesh may rot, but the soul will be reborn. To save the soul from the potential adverse living conditions (e.g. hell), the body, being the transient and thus the less important part, was expected to make sacrifices. To accumulate the best possible karma, pleasures of the flesh had to be given up or at least heavily curtailed.
Naturally the wisdom of this trade-off was questioned by many skeptical minds. The idea of reincarnation may have a strong appeal to imagination, but in absence of any credible evidence the Occam’s razor mercilessly cuts it into pieces. Instead of sacrificing for the sake of the future incarnations, a rationalist should live for the present. But does he really?
Consider the “incarnations” of the same person at different ages. Upon reaching the age of self-awareness, the earlier “incarnations” start making sacrifices for the benefit of the later ones. Dreams of becoming an astronaut at 25 may prompt a child of nine to exercise or study instead of playing. Upon reaching the age of 25, the same child may take a job at the bank and start saving for the potential retirement. Of course, legally all these “incarnations” are just the same person. But beyond jurisprudence, what is it that makes you who you are at the age of nine, twenty five or seventy?
Over the years your body, tastes, goals and the whole worldview are likely to undergo dramatic change. The single thing which remains essentially constant through your entire life is your DNA sequence. Through natural selection, evolution has ensured that we preferentially empathize with those whose DNA sequence is most similar to our own, i.e. our children, siblings and, most importantly, ourselves. But, instinct excepted, is there a reason why a rational self-conscious being must obey a program implanted in us by the unconscious force of evolution? If you identify more with your mind (personality/views/goals/…) than with the DNA sequence, why should you care more for someone who, living many years from now will resemble you less than some actual people living today?
P.S. I am aware that the meaning of “self” was debated by philosophers for many years, but I am really curious about the personal answers of “ordinary” rationalists to this question.
I think this is an important question that is all too easy to gloss over. I for one don't care all that much about myself at 90, especially if I try to put away biases and actually imagine what I will be like at 90 (assuming life extension/uploading fail). Maybe I care a little more about her than I did about my grandparents, and maybe a little less even, since the idea of me being 90 is revolting, and I admittedly don't do a lot of things that would preserve my health over such a long period of time at the cost of pleasure to my current self, and no I haven't done an expected utility calculation involving the imminence of uploading.
Also, the first time I was seriously informed about uploading, I was told that the digital copy of myself could quickly evolve since it wouldn't be shackled by the slowness of neurons, and that it would rapidly become unrecognizable as it correlated its own contents and repaired inconsistencies and set off to fulfill its ultimate utility function.
My reaction was, "Such an abomination must not be! Surely the extreme conclusions of my presently disjoint and unconscious preferences will be something that present me will find horrid. How disgusting to have a perversion of one's own self 'evolve' in a box moments after uploading... Why should present Laura give a damn about boxed Laura if she's so amazingly completely different?" I have since softened this reaction in light of other reflections and other ideas of uploading, but I still don't have a great answer to this basic question.