So I have now scanned through the large volume of responses to this post, in which I asked why it is that scientists seem, on average, to be significantly more liberal in political outlook than the general U.S. population. And I have to say, something very striking has emerged. When I listed some possible explanations at the outset of my post--e.g., conservatives have attacked science lately, so scientists have responded by moving in the other direction; or, academia tilts left, so conservatives tend to distrust its progeny--they all had something in common. They were political explanations, in the sense that they postulated clear and discrete actions by one group leading to opposing reactions from the other. Or to put the point another way: I was suggesting that the two groups had grown distant from one another by virtue of recent developments--but also implying that it didn't necessarily have to be that way. Indeed, that's the same thing I argued in The Republican War on Science: The Republican Party was more science friendly (under Nixon and Eisenhower), but then political dynamics caused it to change and the result was Reagan and Bush II. I certainly didn't argue in that book--or in my latest post--that the real causal factor was some underlying or core difference between liberals and conservatives, of a sort that would affect how they relate to science. But when I looked through all the comments to the latest post, that's what everybody seemed to be arguing. A very large number of folks were postulating deep seated differences between liberals and conservatives that may predispose them for or against scientific thinking. Thus for instance, it was repeatedly suggested that liberalism is associated with more shades-of-gray thinking and an appreciation of complexity, and this goes naturally with the pursuit of science--whereas absolutist or categorical thinking does not (it goes with conservatism). Liberals and conservatives were also contrasted along a kind of hierarch vs. egalitarian axis, with science being defined as a more egalitarian, publicly oriented pursuit. And finally, there was a kind of traditionalism vs. openness/progress axis, in which liberals/scientists were depicted as being in search of the different and new (new findings, new experiences) where as conservatives were painted as resistant to change and attracted to routines, stability, and long existing structures. (Please note that these categorizations and descriptions are not exactly neutral, and I doubt conservatives would go along with them.) What I find interesting about all this is that there is a growing psychological literature--albeit a controversial one--that concerns whether you can really link political outlooks to psychology, different personality types, etc. John Jost of NYU is one psychologist who has gone in this direction. The theme is also present in George Lakoff's work (see here), and social psychologist Jonathan Haidt has similarly postulated that liberals and conservatives have different moral systems. In other words, is political ideology really rooted in psychology? I did nothing to suggest as much, but many of the commenters went there anyway. So this post ends with a different question than the last one: Do readers believe that we need accounts based on psychology and personality in order to explain why scientists seem to be more liberal, or can sheer political explanations (of the sort I initially offered) do the trick? And for those who do want to go the psychology/personality route--please note the kind of argumentative burden you're taking on. First, you need to offer a more ultimate theory of causation if this is what you really think is going on. E.g., why do you believe that people differ from one another in such a way that they end up having different political outlooks or responding differently to scientific information? Are you pinning it on upbringing, or what? (Note that there is a genetic argument, by Alford et al, that is also quite controversial.) And moreover, your explanation has to account for obvious political variation and evolution. Something did change about the U.S. Republican Party over the past 50 years, and it is not clear how psychology explains the transition from the party of Eisenhower to the party of Reagan. Moreover, we sometimes find left-wing anti-science movements and tendencies out there; and on top of that, nobody ever claims to be "anti-science," on any part of the political spectrum. So--it is a hard argument to make, it would seem.