The first question one might ask about the valuable new book by author and activist David Horowitz is how he limited the number to study in the title of The Professors: The 101 Most Dangerous Academics in America. It is a difficulty which Horowitz himself acknowledges early on. “How many radical professors are there on American faculties?,” Horowitz asks. “According to the federal government, the total number of college and university professors in the United States is 617,000.” “If we were to take the Harvard case reviewed at the end of this volume as a yardstick and assume a figure...