Neil Gross is a professor of sociology at the University of British Columbia and a visiting scholar at New York University’s Institute for Public Knowledge. His latest book, Why Are Professors Liberal and Why Do Conservatives Care?, will be published next month by Harvard University Press.

...I analyzed data from surveys and interviews with professors, including a nationally-representative survey of the American professoriate, conducted in 2006 with the sociologist Solon Simmons. My research shows that only about 9 percent of professors are political radicals on the far left, on the basis of their opinions about a wide range of social and political matters, and their self-descriptions (for example, whether they describe themselves as radicals). More common in the professoriate—a left-leaning occupation, to be sure—are progressives, who account for roughly a third of the faculty (and whose redistributionism is more limited in scope), and academics in the center left, who make up an additional 14 percent of professors.

Radical academics, it turns out, are overrepresented not at elite research universities, like Harvard, but at small liberal-arts colleges. Most are concentrated in a handful of social sciences and humanities fields, like mine, sociology (in which radicals are nevertheless in the distinct minority), and in tiny interdisciplinary programs like women’s studies and African-American studies....