We typically think of violence as being caused by a lack of control, or by selfish motives. But what if, more often than not, violence is intended to be morally righteous? That's the thesis of the book Virtuous Violence: Hurting and Killing to Create, Sustain, End, and Honor Social Relationships. Author Tage Rai debates his book's thesis with Julia. Plus: What does The Iliad teach us about changing attitudes about morality over time?