What if I call someone a racist, publicly and repeatedy? Is that harrassment? Does it matter whether the allegation is true or not? Who decides whether it’s true? Should Charles Murray have been prohibited from speaking (on, say, The Bell Curve’s race-and-IQ thesis) because his words would impose a cost on others; or should the students who shouted him down have been prevented from expressing their view that he’s a vile racist, and literally silencing him?