“Professor, why should we allow hate speech?” Over the past few years, that’s become the most common question that students ask me in class. My reply is simple: Human beings have different understandings of hate, love and everything in between. Almost any statement can be perceived as bigoted or offensive, depending on the context. So once we prohibit “hate speech,” we won’t be able to speak at all. And if you disagree, I have two words for you: Salman Rushdie. Rushdie, who was seriously wounded by a knife-wielding assailant on Friday, is probably the most famous purveyor of hate speech in the...