Conservatives, science, academia
Paul Krugman states the obvious: one reason why academics tend to be liberals is that modern conservatism has become increasingly anti-reason and anti-intellectual.
Scientific American may think that evolution is supported by mountains of evidence, but President Bush declares that "the jury is still out." Senator James Inhofe dismisses the vast body of research supporting the scientific consensus on climate change as a "gigantic hoax." And conservative pundits like George Will write approvingly about Michael Crichton's anti-environmentalist fantasies.
Think of the message this sends: today's Republican Party - increasingly dominated by people who believe truth should be determined by revelation, not research - doesn't respect science, or scholarship in general. It shouldn't be surprising that scholars have returned the favor by losing respect for the Republican Party.
But honestly, this reasoning is a little self-congratulatory and superficial (even if it contains a lot of truth). The tendency of academics to be liberal runs much deeper than a reaction against the current wave of know-nothingism in the Republican party.
If we try to put in terms that are as value-neutral as possible, I think that it comes down to
idealism and
universalism. Conservatives tend to take pride in their tough-mindedness, a realistic and hard-nosed approach to the dog-eat-dog world we find ourselves in. Looking out for number one is not only a life strategy, but a moral good. Academics, meanwhile, tend to have a different set of values; not only do they value learning for its own sake (above more straightforward values of material success), but they develop an ability to understand and sympathize with people in different groups and circumstances. In the truest sense of the word, to be "conservative" is to cherish certain established verities, while a good academic is always questioning accepted ideas, and approaching alternatives in a spirit of open-mindedness. That's why you'll always find universities to be mostly liberal, even in the hard sciences (where even the most paranoid conservatives don't think that faculty are hired on the basis of their political views). None of the legislation that David Horowitz tries to get passed will ever change that.