We know that violence breeds violence. We need look no further than the wars in the western Balkans, the genocide in Rwanda, or the ongoing crisis in Israel and Palestine. But we don’t know how to deal with the messy moral and political quandaries that result when victims become perpetrators. When the line between guilt and innocence wavers and we are confronted by the suffering of the victim who turns to violence, judgment may give way to moral relativism or liberal tolerance,...