Professors are liberal and have become more strikingly so in the past twenty years. At present sixty percent of professors identify as liberal, while only fifteen percent identify as conservative.
This is often taken as evidence of an academic culture hostile to conservatives. However, surely that is only one of two possible explanations.
After all, there is a broad academic consensus on many issues. For example, if one were to poll academics about whether dinosaurs have feathers, or who Euclid is, or the plot of Oliver Twist, one would expect academics in general to have more accurate answers than the general public. This is not because of any bias in academic against people who think dinosaurs didn’t have feathers; it is because it is actually true that dinosaurs had feathers, and the whole point of academia is to find out true things. We’d expect even non-paleontologists to be more likely to get the correct answer; perhaps they happened to talk with a paleontologist at lunch one day and the paleontologist set them straight about the matter.
The accuracy of academic consensus is true even for politicized issues. Far more than sixty percent of academics believe the Earth is billions of years old and life evolved through a process of natural selection. This is not because of anti-young-earth creationist bias, no matter how much Answers in Genesis complains. It’s simply because it is actually true that the Earth is billions of years old and life evolved through a process of natural selection. (Note that young-earth creationists do, in fact face a hostile environment in academia. People tend to mock them and they are often discriminated against in hiring. It is nevertheless true that this hostile environment does not cause the underrepresentation of young-earth creationists in biology; the causation goes the other way.)
So, when considering why so many academics are liberal, we must consider two hypotheses. First, there is a hostile environment driving conservatives out of academia; second, liberals are correct and thus successfully convince their most avid and able students, the same way that biologists convince even young-earth creationist biology majors that evolution is true.
It would be very strange, after all, if both liberals and conservatives were exactly 50% right about everything. Even if rightness were randomly distributed, one group would be more right than the other, simply by chance. And if you have to gamble on a single group to be more likely to be right than the other, then it’s probably safest to bet on the one favored by more highly educated people; we expect that, in general, people with PhDs are going to have more correct opinions than people who dropped out of high school. Of course, I have a particular reason to be sympathetic to this hypothesis. Being a liberal myself, I do in fact think liberals are right on more policy issues than conservatives are (although I also occasionally fantasize about dropping an anvil labeled REGULATORY CAPTURE on various liberals’ heads).
And many, many fields influence one’s opinion on politics. Of course, the entirety of social science has political implications. So do many scientific fields, such as ecology and epidemiology, and many fields in the humanities, such as history and philosophy. So we’d expect many academics to have their opinions on politics influenced by their research (as well as, say, discussions with fellow academics).
Even if liberals have more correct positions on average, they are unlikely to be perfectly right about everything. So we’d expect even if professors consider themselves liberal, their actual political opinions would often be kind of weird and hard to classify into the left/right binary. In economics, which as far as I know is the only social science field that polls its academics sometimes to find out what the academic consensus is, this is true. Economists, like professors as a whole, are about sixty percent liberal. Conversely, their actual beliefs are kind of weird and not exactly what I would call a liberal orthodoxy.
I don’t mean to say that it is definitely true that liberals outnumber conservatives in academia because liberals are right about everything. Indeed, I can see a solid case for the other hypothesis. We know that people can feel excluded from an environment due to an endless accumulation of individually small slights. Surely that could also apply to the conservative student in a sociology class whose teacher jokes about the president resembling a Cheeto and presents sociological ideas on a spectrum from liberal to Marxist, with nary a mention of conservative viewpoints. We know that discrimination often happens on a subconscious level, even in people who sincerely believe they don’t hate anyone and are just judging the work on the merit. Surely a liberal hiring committee who sincerely believes they’re looking for the best candidate, regardless of the candidate’s political opinions, might form unconscious judgments based on the candidate’s conservative political volunteering or papers.
However, the fact that there exists a difference does not mean that it exists because of discrimination. This is particularly true for political beliefs, which involve empirical claims about how the world works. The academy could theoretically represent genders, races, sexual orientations, levels of ability, classes and so on and so forth in accordance with how common they are in the population, without sacrificing academic quality; it would be very very difficult and involve a massive restructuring of society, but it could be done. The academy could not, even in theory, represent all ideas equally in accordance with how common they are in the population. You are simply not going to get as many anti-vaxxer epidemiologists as pro-vaccine epidemiologists without making the entire field of epidemiology useless.
So I suggest that interested people begin a research program into discrimination against conservatives in academia, perhaps using all the tools used to study discrimination against women, people of color, and poor people. I would also be interested to see the results of an affirmative action program for conservative professors; maybe conservative students would experience a less hostile environment and would have high-achieving conservative role models, and thus would be more likely to consider graduate school.