Stanley Milgram's famous Yale experiment set the standard for uncovering the capacity for sadism in ordinary people. The results came as no big surprise to parents of multiple kids.
Philip Zimbardo's Stanford Prison Experiment ("SPE") took the subject much further - as far as any researcher would want to take it. He is the author of The Lucifer Effect: Understanding How Good People Turn Evil.
Dr. Zimbardo is interviewed this week in the NYT Science Times.
The evil lurking in people only comes as a surprise to those who know nothing of themselves. Dealing with it is one of the challenges of being human. And dealing with the vicissitudes of human aggression and sadism/sado-masochism (and anger too, which is another subject entirely) is a major challenge in psychiatry, both theoretically and practically. Freud found it necessary to posit a "death instinct" to account for some of these things, but he was never entirely satisfied with the idea.
Denial of the capacity for evil in others is called naive, or infantile. Denial of evil in one's self is called "denial," and is usually handled via projection (an immature defense mechanism which "projects" one's own malevolence onto external sources). Those who locate evil only in themselves are often masochistic, or using various defence mechanisms which I will not get into now.
The devil? Many Christians and Jews believe in a devil or devils. Devil or no, there is plenty enough material in humans for a devil to exploit (see Screwtape Letters - a diabolically fascinating and amusing read). Our first piece on evil is here.
I have done evil, and I have sinned plenty. Not to brag. I know that evil exists.
