"An issue of the New Yorker Magazine featured a very interesting article about psychopathology. A psychopath (sometimes also called a sociopath) is a person without a conscience - one who lies, cheats, steals and in some cases rapes and murders without compunction. It is estimated that about 6% of the people are psychopaths, though degree of psychopathology is thought to vary among individuals.
Being a psychopath is not a form of mental illness, since such people are in fact not delusional or cognitively impaired in the usual sense. Whether they are "rational" is sometimes debated, since they tend to be impulsive and have very limited capacity either to anticipate the consequences of their social actions or to learn from their social mistakes. They are often very intelligent (e.g., Ted Bundy), and often are also spectacularly effective manipulators. Ted Bundy, a guy who raped, tortured and murdered dozens of young women was described as "charming," "hypnotic" and "mesmerizing" by many who knew him - even those who met him after it was known what he had done.
For a long time psychologists and psychiatrists tended to pay little attention to psychopathology. In part this disregard was because of the difficulty of defining psychopathology (i.e., figuring out how to identify them) and in part been because it was generally thought that there is no effective "treatment" for psychopaths. And in fact traditional talk therapy seems to make the condition worse - psychopaths who undergo psychotherapy learn to become more effective manipulators.
Recently, though, some psychologists have taken to studying the brain scans of psychopaths who have landed in prison (it is estimated to about a third of those in prison are psychopathic) and have found they their brains are structurally different from so-called normal people. A rationale for this research has been that if we know what is wrong with psychopathic brains we can find a treatment for them ("open skull, insert conscience, close skull").
Undiscussed though is a (perhaps) troubling implication of these findings. If psychopaths are different from the rest of us in brain structure, and by implication in their DNA, are they in fact ultimately human? Is it not arguable that they are something like another species, an alien species, living among us unnoticed because they outwardly resemble us so much? And if they are another species, is it not arguable that we can take preemptive action to be rid of them (e.g., abort fetuses with the offending DNA). We have never had very many qualms about getting rid of other species we find a inconvenient (e.g., timber wolves and the Great Apes.) And psychopaths seem to me to be much more dangerous than any of the species that are currently on the way out.
Apparently psychopaths are found in all cultures and communities. Among the Yupik Eskimos, for example, the word "kunlangeta" is used to describe a man who lies, steals, cheats and takes sexual advantage of women. In an 1976 study of the Yupik, Harvard anthropologist Jane M. Murphy asked a tribal elder what the community did when a kunlangeta appeared among them. He replied, "Someone pushes him off the ice when no one else was looking."