The Green Man posted at the time of the Abu Ghraib atrocity on the flaw in human nature that leads to ordinary people behaving in a manner that seems completely inhuman.

In 1971 Philip Zimbardo conducted an experiment in the basement of a Stanford University building. Volunteers were assigned randomly to be either a prison guard or a prisoner and they were left to their own devices. The outcome was essentially the same as Abu Ghraib. Dr Zimbardo explains

prisons offer an environment where the balance of power is so unequal that even normal people without any apparent prior psychological problems can become brutal and abusive unless great efforts are made by the institution to control the expression of guards' hostile impulses . . . It's not that we put bad apples in a good barrel. We put good apples in a bad barrel. The barrel corrupts anything that it touches

I think we know that not only was there no effort to "expression of guards' hostile impulses" at Abu Ghraib it was probably encouraged. Anyway if you want to see the documentary on this ground breaking research that would now, quite correctly, be regarded as unethical. It is available on U-Tube. Visit Pure Pedantry