Meg's post sounds convincing to me. It can be summarized simply as follows: to explain a problem, one can make educated assumptions about what would be rational behavior for an individual or a group, but one shouldn't reach conclusions on the basis of these assumption; test them by probing as deep as possible.
"Legwork" is not a bad word. Some would call it "common sense."

FWIW.

Ehud, A.K.