I recall reading somewhere that Keynes criticized Russell for saying that the problem with the world is that people are irrational and that the solution is that they should become rational. It seems a fair comment on Russell–but why is it a criticism? Because Russell’s observation is a datum not an explanation: we want to know why people are irrational andhow to improve their rationality. It’s obvious what the problem is and also what the solution would be–but we need to know what causes irrationality and what we can do to fix it. Freud had a kind of theory of this but nowadays it looks pretty wacky. There seems to be a big theoretical gap here, urgently needing to be filled. (Of course, we won’t recognize it if we start doubting that rationality is a robust matter.) I don’t have a theory myself–human irrationality can seem the oddest and least adaptive trait of the species–but I do think we need to work on it. Why do people go around believing silly things and acting idiotically?