In defence of economics, I think it is justified in sticking to its guns and expecting humans to act rationally ;-). Various other fields (e.g: law) do so, and so do we in general. In fact it is a science-in- waiting -- a sort of mathematics, if you will. IMVVVHO the real problem is that a lot of mainstream economics seems to have a very vulgar (substitute 'reductionist' if you wish) understanding of 'rationality'.
--ravi
