The manipulative con-man. The guy who lies to your face, even when he doesn’t have to. The child who tortures animals. The cold-blooded killer. Psychopaths are characterised by an absence of empathy and poor impulse control, with a total lack of conscience. About 1% of the total population can be defined as psychopaths, according to a detailed psychological profile checklist. They tend to be egocentric, callous, manipulative, deceptive, superficial, irresponsible and parasitic, even predatory. The majority of psychopaths are not violent and many do very well in jobs where their personality traits are advantageous and their social tendencies tolerated. However, some have a predisposition to calculated, “instrumental” violence; violence that is cold-blooded, planned and goal-directed. Psychopaths are vastly over-represented among criminals; it is estimated they make up about 20% of the inmates of most prisons. They commit over half of all violent crimes and are 3-4 times more likely to re-offend. They are almost entirely refractory to rehabilitation. These are not nice people.