Oh, the irony! Liberal activist Sally Kohn is the author of "The Opposite of Hate: A Field Guide to Repairing Our Humanity." Amazon describes her as someone "learning how to talk respectfully with people whose views she disagrees with passionately . . . It was time, she decided, to look into the epidemic of hate all around us and learn how we can stop it." And: "In The Opposite of Hate, Kohn talks to leading scientists and researchers, investigating the evolutionary and cultural roots of hate and how simple incivility can be a gateway to much worse." But when she...