Because the world might be going to hell in handbasket, or it might not. And either way, there's essentially nothing that that you or I can (reasonably) expect to do about it. Or not quite nothing, but probabilistically speaking, epsilon close to nothing.
However to the extent that any of us might, just might, be able to help steer this civilization out of the death spiral it seems currently locked into -- such a correction will, almost by definition, require a very strong degree of (the right kind of) optimism. If we just say "F it", and give into pessimism -- we won't have any chance at all.
Therefore, from rationalist first principles -- we might as well go with optimism. In fact if the current situation we're in can be thought of as an evolutionary test -- then it is one that is selecting for 3 traits: (1) intelligence, (2) ability to cooperate, and (3) optimism (again, of a certain "right kind" that I don't have time to go into at present).
I realize this argument sounds a bit pat (like Anselm's argument for the existence of God), but I do think there's a lot more substance to it.
personally I believe the most rational approach is to believe realistically and act optimistically. I believe whatever I think is most likely to be true, not what I want to be true. However in certain cases I may act as if what I wish were true is in fact true, just because it makes life better (doesn't apply to all scenarios though)
Why believe at all? What will happen will happen. If that's the end of civilization or a golden utopia will reveal itself in due time. Regardless, the way to act is the same, that is, true to yourself.
However to the extent that any of us might, just might, be able to help steer this civilization out of the death spiral it seems currently locked into -- such a correction will, almost by definition, require a very strong degree of (the right kind of) optimism. If we just say "F it", and give into pessimism -- we won't have any chance at all.
Therefore, from rationalist first principles -- we might as well go with optimism. In fact if the current situation we're in can be thought of as an evolutionary test -- then it is one that is selecting for 3 traits: (1) intelligence, (2) ability to cooperate, and (3) optimism (again, of a certain "right kind" that I don't have time to go into at present).
I realize this argument sounds a bit pat (like Anselm's argument for the existence of God), but I do think there's a lot more substance to it.