The Israel-Hamas war has provoked an angry, bitter debate over the meaning of genocide as partisans on both sides of the conflict invoke the memory of the Nazis and the Holocaust. The new Netflix documentary "Ordinary Men" -- based on the 1992 book of the same title by historian Christopher Browning -- may help place this use (or misuse) of history in its proper perspective. "Ordinary Men" confonts us with unsettling questions concerning humans' capacity to inflict cruelty on others. In this episode, historian Thomas Kuehne discusses the psychological aspects of mass murder and the difficulty in drawing comparisons between, for instance, Hamas and the Nazis.