There was a certain naïveté in how liberals used to approach free speech, said Frederick Schauer, a law professor at the University of Virginia. “Because so many free-speech claims of the 1950s and 1960s involved anti-obscenity claims, or civil rights and anti-Vietnam War protests, it was easy for the left to sympathize with the speakers or believe that speech in general was harmless,” he said. “But the claim that speech was harmless or causally inert was never true, even if it has taken recent events to convince the left of that. The question, then, is why the left ever believed otherwise.”&n...