Why is it so hard to draw the line between what’s funny or offensive? We love to laugh and we prize a good sense of humor in ourselves and others. But the ancient Greeks – Aristotle and Plato – said humor was bad for society: they thought of it mainly as mockery and laughing was a loss of self-control. When you consider how quickly humor can go wrong in the hands of a bully or an edgy standup routine, you have to wonder – were the Greek philosophers right?