Some Notes on Instrumental Rationality
a general response to several Less Wrong posts and comments
"Abandon reasonableness" is never necessary; though I think we may be using reasonable somewhat differently. I think "reasonable" includes the idea of "appropriate to the situation"
As to the overall point, I agree that rationalists should win. General randomness, unknowns, and opposition from other agents prevent consistent victories in the real world. But if you are not winning more than losing you definitely are not being rational.
Another reason for failure is a failure of knowledge. It's possible simply not to know something you need to succeed, at the time you need it. No one can know everything they might possibly need to. It is not irrational, if you did not know that you would need to know beforehand.
A bad reason for failure is the faulty assumption that something is possible to accomplish when it's not (eg, perpetual motion and its less obvious equivalents). And of course there's the complementary problem: "If the objection you think is real, is in fact real, well, then you've only lost a little time by trying. But if you believe an objection that isn't real, then you've lost much, much more than that.", P J Eby commenting on "Bad Reasons for Rationalist to Lose", that is not trying something because you wrongly think it is impossible.