How far are Americans willing to go to force each other to fall in line?According to the establishment media, the intelligentsia, and our political chattering class, the greatest threat to American freedom lies in right-wing authoritarianism. We've heard that some 75 million Americans who voted for Donald Trump represent the rise of American fascism; that conservatives have allowed authoritarianism to bloom in their midst, creating a grave danger for the republic.But what if the true authoritarian threat to America doesn't come from the political right, but from the supposedly anti-fascist left?There are certainly totalitarians on the political Right. But statistically, they represent a fringe movement with little institutional clout. The authoritarian left, meanwhile, is ascendant in nearly every area of American life. A small number of leftists—college-educated, coastal, and uncompromising—have not just taken over the...