Robin Hanson talks a lot about the gap between the stated and actual purposes of various human institutions. People often look irrational relative to the stated purpose but quite rational relative to the actual purpose.
Of course, that often ends up being tautological, because the tendency for folks like Robin Hanson is to define the "actual purpose" as "the purpose relative to which the behavior would be rational".
(This is not a critique, incidentally -- it may be a notable fact when behavior appears to be optimizing anything at all.)
This is true but I think the ultimate test of a Hansonian view of human institutions (as of any view) is whether employing it allows you to make more accurate predictions and thus better decisions. It is my belief that learning about economics, evolutionary psychology and Hansonian-type explanations for otherwise puzzling human behaviour has improved my ability to make predictions. I do not currently have hard data to provide strong evidence to support this belief to others. Figuring out how to test this belief and produce such data is something I'm active...
Some research says that lurkers make up over 90% of online groups. I suspect that Less Wrong has an even higher percentage of lurkers than other online communities.
Please post a comment in this thread saying "Hi." You can say more if you want, but just posting "Hi" is good for a guaranteed free point of karma.
Also see the introduction thread.