"Evil is the most serious of our moral problems. All over the world cruelty, greed, prejudice, and fanaticism ruin the lives of countless victims. Outrage provokes outrage. Millions nurture seething hatred of real or imagined enemies, revealing savage and destructive tendencies in human nature. Understanding this challenges our optimistic illusions about the effectiveness of reason and morality in bettering human lives. But abandoning these illusions...