Thirty-one years ago, the late political philosopher and cultural critic Allan Bloom wrote a book that his publishers expected would sell a paltry few copies to university types. Instead, it went on, in an improbable pre-Internet version of “going viral,” to occupy a high perch on best-seller lists for four months. (And generate heated discussion among the intelligentsia for years after that.) Its title: “The Closing of the American Mind: How Higher Education Has Failed Democracy and Impoverished the Souls of Today’s Students.” In it, Bloom, a classicist who was admitted to the University of Chicago at age 15 and graduated three years…