Liberal math? (Akash Kataruka/Flickr)

If you've spent time in a college or university any time in the past quarter-century you probably aren't surprised to hear that professors have become strikingly more liberal. In 1990, according to survey data by the Higher Education Research Institute (HERI) at UCLA, 42 percent of professors identified as "liberal" or "far-left." By 2014, that number had jumped to 60 percent.

Over the same period, the number of academics identifying as "moderate" fell by 13 percentage points, and the share of "conservative" and "far-right" professors dropped nearly six points. In the academy, liberals now outnumber conservatives by roughly 5 to 1. Among the general public, on the other hand, conservatives are considerably more prevalent than liberals and have been for some time.

In itself this isn't necessarily a huge problem. Certain industries — think big business and the military — tend to be dominated by conservatives. You're never going to achieve perfect ideological parity in every field and to try would be foolhardy.

But the folks that first put these numbers together, a group of academic faculty calling themselves Heterodox Academy, argue that homogeneity in higher education is a bigger problem than it is in other areas. "With relatively few right-leaning voices in the professoriate, particularly in the humanities and the social sciences where ideas matter most, many college students receive less than the intellectually rigorous education than [sic] they deserve," some of the group's members recently wrote.

Interestingly academics are, on the whole, considerably more liberal than even their students. HERI has also been surveying incoming college freshmen for a number of years. America's students are much more likely to refer to themselves as "moderate" than as liberal or conservative.

The share of self-identified liberals among students has risen, but much less dramatically than the increase in liberalism among professors. Here's a chart the nicely illustrates that point. It shows that gap between the percent of professors calling themselves "liberal" or "far-left," and the percent of students saying the same.

A quarter-century ago, college professors were about 16 percentage points more likely to identify as "liberal" or "far-left" than their first-year students. By 2014, professors were close to 30 percentage points more likely than freshmen to call themselves liberal.

HERI's numbers suggest that professors' liberal tilt does have some impact on their students' ideology, but not much. They've started surveying graduating college seniors in recent years. While they don't have many years of data available yet, in 2009 they found that "the proportion of students who characterized their political views as liberal or far left increased 9.2 percentage points from freshman to senior year."

Among the college class of 2009, 39.1 percent identified as liberals, 38.5 percent called themselves moderates, and 22.5 percent said they were conservatives. While more liberal and less conservative than the general public, the seniors were also considerably less liberal and more conservative than the people who taught them.

So fears that universities will indoctrinate your children and turn them into a bunch of bearded Marxist automatons are probably unfounded. That said, American politics seems to work best when the two main factions are animated by rigorous thinking and serious ideas. And if there's no home for conservative ideas at today's colleges, it stands to reason that our political discourse will be poorer for it.

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