I always think what economists and psychologists do are two different things -- that can in times work complementary. I myself am not very interested in knowing how the mind works, albeit it is very important thing. It's enough for me to understand at the outset why people do a particular, interesting thing (that is to say: not everything interests me) without having to know his/her state of mind. Yes, it (this approach) might be more powerful to explain ex post situation, but it might as well be useful to help predict similar behavior in the future given similar condition, more or less. What the second Daniel says i think is also true, at least in my case: I trust (more on) what people do, not what they say or feel. In some cases though, I have to rely on what people say -- that is, when I lack the observation of what they do. So, I think it's extremely useful that psychologists teach us how the mind works -- but at least for me, it is useful only to make us know how the mind works.(To be continued -- probably).