What on earth is going on in the Western democracies? From the rise of Donald Trump in the United States and an assortment of right-wing parties across Europe through the June 23 Brexit vote, many on the Left have the sense that something dangerous and ugly is spreading: right-wing populism, seen as the Zika virus of politics. Something has gotten into “those people” that makes them vote in ways that seem—to their critics—likely to harm their own material interests, at least if their leaders follow through in implementing isolationist policies that slow economic growth. Most analyses published since the Brexit vote...