Survivors of Auschwitz as much as latter-day observers repeatedly point to one trait that was common to all camp guards, even the cruelest ones. That trait was behavioral inconsistency. In the same place, often in the course of the same day or even hour, a person could help one prisoner and, without batting an eyelash, send another to his death. It was not that good and evil had reached some kind of equilibrium - evil had the upper hand, by far - but rather that there was no guard who was wicked through and through. Instead, all the guards seemed subject to constant shifts in attitude and temperament, so much so in fact that there is no better word to describe their behavior than "schizophrenic," even though none of these people, as far as we know, had any specific mental illness. What we have here is the "social schizophrenia" specific to totalitarian regimes. As Primo Levi observes, "Compassion and brutality can coexist in the same individual and in the same moment, despite all logic."
- From Facing the Extreme: Moral Life in the Concentration Camps by Tzvetan Todorov
[I'm reading this now. Fascinating book.]