Baumeister's point is that we have a deep need to understand violence and cruelty through what he calls "the myth of pure evil." Of this myth's many parts, the most important are that evildoers are pure in their evil motives (they have no motives for their actions beyond sadism and greed); victims are pure in their victimhood (they did nothing to bring about their victimization); and evil comes from outside and is associated with a group or force that attacks our group. Furthermore, anyone who questions the application of the myth, who dares muddy the waters of moral certainty, is in league with evil.

Jonathan Haidt