One of the proposed benefits of life extension is that it will help us long term plan as we will be around in the future, so we will be more likely to care about the long term future of the world if we live longer.
So is this true? Are we rational in this respect or will the mind recoil from thinking in time scales longer than 40-60 years even when we are living hundreds of years, due to biases intrinsic to the mammalian brain.
I don't have time to research this question right now, so I thought I would experiment by throwing out this question to lesswrong and see how people treat it.
I think that the failure of long-term planning in humans is not because we live any specific amount of time, but because we live for a finite amount of time. Only when days and years and decades all the way on up become unlimited (or practically so; we may always be limited by the heat death of the universe or something) and too cheap to meter would I expect to see explosions in long-term thinking.
Can you elaborate on why you believe that? I find it difficult to see how, if lifespans were still finite but measured in millennia instead of decades, it could not have major consequences for long-term planning (on the order of decades to centuries).