In the September/October 2010 edition of Scientific American Mind, I recently read an article titled "Inside the Mind of a Psychopath," by Kent Kiehl and Joshua W Buckholtz. Who are psychopaths? The authors claim that psychopaths are people whose brains have "gone wrong." They claim that psychopaths make up .5 to 1% of the general population, adding up to 250,000 psychopaths living freely in the United States. They offer a list of criteria for determining whether a person is a psychopath, mentioning that "everyone falls somewhere on the psychopathic continuum." What are the basic symptoms?

One of the most striking peculiarities of psychopaths is that they lack empathy; they are able to shake off as mere tinsel the most universal social obligations. They lie and manipulate yet feel no compunction or regrets-in fact, they don't feel particularly deeply about anything at all. So much for the way regular people make sense of the world is through emotion. It informs our gut decisions, our connections to people and places, our sense of belonging and purpose. It is almost impossible to imagine life without findings-until you meet a psychopath. But psychopaths often cover up their deficiencies with a ready and engaging charm, so it can take time to realize what you are dealing with.