I've been listening a lot to Slavoj Zizek recently and he discusses this often. His argument is that to make good people do horrible things, you need an ideolog

I've been listening a lot to Slavoj Zizek recently and he discusses this often. His argument is that to make good people do horrible things, you need an ideology that basically says that you are an agent of "what must be done" and then the ends justify the means. He describes how Nazi soldiers, who were instinctively horrified by what they were doing, were instructed to try to dissociate from their bodies and their actions, and identify themselves completely and impersonally with the nationalist cause.