Long before Senator McCarthy enjoyed his hour of disreputable fame, another Joseph had discovered how to deal effectively with political rivals. Not only the inquisitive senator, but every political inquisitor since, has owed a primary debt to Comrade Stalin. It was Stalin’s sinister genius to realize that arguing a case was not the best way to prevail in a dispute. Engaging his opponents on the merits of their critique was not his choice. Instead, he arranged show trials to conflate them with Adolf Hitler and purge them from his party’s ranks. So why should it surprise me when the left-wing...