In my mind, the most thought-provoking answer was by Philip Zimbardo -- Psychologist, emeritus professor, Stanford; and author of "Shyness." Here's what he said:
I believe that the prison guards at the Abu Ghraib Prison in Iraq, who worked the night shift in Tier 1A, where prisoners were physically and psychologically abused, had surrendered their free will and personal responsibility during these episodes of mayhem.
But I could not prove it in a court of law. These eight Army reservists were trapped in a unique situation in which the behavioral context came to dominate individual dispositions, values and morality to such an extent that they were transformed into mindless actors alienated from their normal sense of personal accountability for their actions - at that time and place.
The "group mind" that developed among these soldiers was created by a set of known social psychological conditions, some of which are nicely featured in Golding's "Lord of the Flies." The same processes that I witnessed in my Stanford Prison Experiment were clearly operating in that remote place: deindividuation, dehumanization, boredom, groupthink, role-playing, rule control and more.
I have no problem believing that the prisoners at Abu Ghraib were in some kind of "Twilight Zone" where they were deprived of free-will. I have a lot of difficulty believing that the guards had "surrendered their free will and personal responsibility" and became "mindless actors."
Ask any one of those guards if they treated detainees the way they hope Americans would be treated if they became prisoners.
The Golden Rule may be too simplistic for Alberto Gonzales, Gen. Boykin and the bureaucrats who put the guards in control of the prison, but it's still a pretty good rule of thumb for anybody who lives with a conscience.