Todd Zywicki of The VC links to research done by Dan Klein showing that Republicans are vastly underrepresented in the halls of academia. The combined rate of Democrats to Republicans at Stanford and Berkeley is 9:1, and judging by the rate of tenure-track hires it is getting worse. What does this mean?
Zywicki correctly notes that if this was the gender or race based disparity, people would be throwing a fit. And certainly, these statistics are distressing. However, there are some important differences between under-represented ideologies vs. under-represented races or genders. The reason is that while there shouldn't, in theory, be any reason why a particular race would avoid academia, it is quite conceivable that a group based on ideological persuasion might prefer to do other things. That's one of the reasons that race is considered a suspect class and political parties aren't: political party members necessarily share certain values and characteristics, while race and gender based characteristics are overwhelmingly based on stereotype. So it does make a certain degree of sense that softy, idealistic liberals may want to go into teaching and sacrifice the allure of money and power, while hardheaded, realistic conservatives would either enter the private sector or think tanks where they can make more cash and influence authority. I'm not saying this is true, but it is far more reasonable a proposition than any non-discrimination based argument for why Blacks are underrepresented (I include in "discrimination" the continued economic disadvantages faced by minorities as a legacy of past discrimination).
The real question is: Are there significant numbers of Republicans who wish to enter Academia but either a) face institutional obstacles to doing so (such as biased administrators) or b) feel academia is a "hostile environment" to persons with their views? If either of those are true, then we may have a case. But more research needs to be done first.