Philip Zimbardo talks about the psychology of evil in one of his TED talks. It was one of the most intense TED videos I have ever seen(link here). In his early days at Stanford, he did some experiments on innocent people to test if the evil in them is surfaced or not given a certain situation. What he found out that people from every walk of life behaved almost all the same meaning their evilness was surfaced and it was pretty ugly.
He shared the similarity between his experiment and an event occurred in Abu Ghraib Detention Center Iraq, and the images were very disturbing. The conclusion was that given a situation we have a choice but it’s not a simple one (and most of us fall in the slippery slope of evil). He also shared how people with authority uses their power to bring out evil in us(it was scary but true).
The line between good and evil is permeable and almost anyone can be induced to cross it when pressured by situational forces.
He ended on a note that we should live a life as if we are a “hero-in-waiting” because every once in a while we are thrown into a situation where we have to act on behalf of others and at that point in life we become the hero of our life if we act.