I'm always reminded of the Milgram experiment, where someone is told to shock someone in increasingly high levels for getting answers wrong. They hear the voice of an actor on the other side, giving wrong answers, freaking out, and screaming. The majority always put it up to lethal levels, were paid, and left. For all they knew, they killed someone.

Anyone, given the right circumstances, would kill someone. Well, almost anyone. What those circumstances are though, is likely far less than we would like to imagine. In reality, someone who is an authority figure telling us to might be enough. We could all be possible complacent actors in some future atrocity.