The American Conservative has an interesting and reasonably balanced article on the subject.
Here is the link: http://www.theamericanconservative.com/articles/why-isnt-my-professor-conservative/
The Washington Post has a piece on professors becoming more liberal.
Comments to these types of articles are always illuminating. More often than not, they highlight the various ways that ideology works. For example, despite evidence to the contrary, many self-identified faculty simply deny the problem and then go on to stereotype conservatives as anti-science. They forget or don’t know that research has found that liberals and conservatives are both “anti-science” when it suites them. And then we have my favorite argument: All of my colleagues are liberal and intelligent so conservatives must not be bright enough.
One point brought out in the American Conservative article is that some questions do not tend to get asked when people share the same assumptions. I think this is spot on and will discuss the issue in more detail later.
John Paul Wright and Matt DeLisi
Professors of Crime and Criminology