The last article “Are Humans Moral?” started an interesting debate on the topic are humans evil or is it the situations which make a normal person evil? What are the underlying factors which make crowds behave aggressively and how should the negative tendencies be controlled?
Geoffrey Morton-Haworth mentioned the video “The Lucifer Effect: Understanding How Good People Turn Evil” by Philip Zimbardo available at http://mitworld.mit.edu/video/459. It is nearly a two-hour presentation covering the abusive behavior of US army staff in the prison of Abu Gharib. Philip Zimbardo has drawn connections between the prison situation in Abu Gharib and Standford Prison Experiment, to explain the sociological impact of the situations on normal human behavior. He has discussed how the same situation can trigger in one human evil tendencies and in another heroic behavior.
I recommend you to watch the video to understand how irrational emotions of human beings can be triggered to make them behave in extremely negative behavior.
I have below given the link to Part I of the same video on youtube. The video contains explicit and disturbing images, so please be careful.