The Liberal Blind Spot

CLASSIC liberalism exalted tolerance, reflected in a line often (and probably wrongly) attributed to Voltaire: “I disapprove of what you say, but I will defend to the death your right to say it.”

On university campuses, that is sometimes updated to: “I disapprove of what you say, so shut up.”

In a column a few weeks ago, I offered “a confession of liberal intolerance,” criticizing my fellow progressives for promoting all kinds of diversity on campuses — except ideological. I argued that universities risk becoming liberal echo chambers and hostile...