One of the most obvious and blatant benefits of atrocity is that it quite simply scares the hell out of people. The raw horror and savagery of those who murder and abuse cause people to flee, hide, and defend themselves feebly, and often their victims respond with mute passivity. We see this in the newspapers daily when we read of victims who are faced with mass murderers and simply do nothing to protect themselves or others. Hannah Arendt noted this failure to resist the Nazis in her study The Banality of Evil.
