Last week, a new study revealed that a commanding majority of professors are liberal (75%, vs. 15% who identify as conservative), and the study's author, Stanley Rothman, suggested that a liberal bias in hiring might be involved. However, it's not just poli sci—even faculty in the hard sciences are more likely to be liberal.
Paul Krugman suggests that there are two reasons. First, self-selection: people who gravitate to academia are more likely to be liberal, while more conservatives opt for the private sector. The bigger reason, though, is the difference in what liberals and conservatives value most, Krugman writes:
"...There's also, crucially, a values issue. In the 1970's, even Democrats like Daniel Patrick Moynihan conceded that the Republican Party was the 'party of ideas.' Today, even Republicans like Representative Chris Shays concede that it has become the 'party of theocracy.'"
A Florida legislator has sponsored a bill that would allow students to sue their professors for disrespecting their conservative views—such as when the biology professor presents evolution as, well, scientific fact.
Krugman continues, "...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."
Once again, liberal economics professor Krugman makes perfect sense to me. But then, I value scientific inquiry a lot more than right-wing interpretations of the bible, so that must be my liberal bias popping up.