Psychopathy is a personality disorder whose hallmark is a lack of empathy. Researcher Robert Hare, whose Hare Psychopathy Checklist is widely used, describes psychopaths as "intraspecies predators who use charisma, manipulation, intimidation, sexual intercourse and violence to control others and to satisfy their own needs. Lacking in conscience and empathy, they take what they want and do as they please, violating social norms and expectations without guilt or remorse". "What is missing, in other words, are the very qualities that allow a human being to live in social harmony."
Psychopaths are glib and superficially charming, and many psychopaths are excellent mimics of normal human emotion; some psychopaths can blend in, undetected, in a variety of surroundings, including corporate environments. There is neither a cure nor any effective treatment for psychopathy; there are no medications or other techniques which can instill empathy, and psychopaths who undergo traditional talk therapy only become more adept at manipulating others. The consensus among researchers is that psychopathy stems from a specific neurological disorder which is biological in origin and present from birth. It is estimated that one percent of the general population are psychopaths.