Today I listened to Shadd Maruna's lecture titled Why We Need Psychopaths. The talk questions the current construct of psychopath and suggests that it's simply due to our projection of our own dark side onto others as a way to deny the fact that we could all slip into such evil quite easily. To be honest, I didn't find his talk all that enlightening. Maruna focused on Hare's system for diagnosing psychopathy, which relies on the factors shown below. (There's still debate on whether it should be four-factored as shown below or should be arranged a different way.)
I was amazed to learn that the diagnostic does an excellent job of predicting which recidivism among criminals. Of course, just looking at criminal records apparently predicts about as well. As Maruna mentions, the description of psychopaths fits in very well with the worst villains shown in Hollywood films.
One of Maruna's objections regarding the diagnostic is that it assumes that people are unable to change. I'd agree that we should this isn't the case. One thing I don't understand is that if a fixed proportion of society are psychopaths from birth (apparently due to genetics perhaps with triggers during their upbringing), why do we see so few criminals in some societies?