Awoke during the night and thought--I'm not asking the right question (am I dedicated to blogging or what). Thought of fraternities. And of the gender gap.
Iraq and WMD showed it's important to ask the right questions. With respect to liberals and academia there may be several right questions, but one is not: "why is academia liberal?" Compare the issue to the "gender gap". The question there was something like: "why are men voting more Republican than women, or vice versa?" In other words, the issue was the comparattive relationship of two groups, not the absolute character of one group.
So a right question could be: "why are people in the private for-profit sector voting more Republican than academics?"
Thinking of fraternities, say the Dekes, did they choose the party animals or did they create them? How about Americans, did the most entrepreneurial people choose to emigrate or America create them? I think the answer in both cases is: both. But separating the processes of recruitment versus culture may help the discussion.
So another right question could be: "is academia more attractive to young liberals or Democrats than the private sector or does it create liberals or Democrats from those it attracts?"
Of course neither of the right questions address Krugman's original issue of the liberalism of natural scientists. Deciding the right question there I'll save for my next sleepless night. And the job of reworking what I've gathered from blogs and my earlier attempts here and here will have to wait.