A fascinating, if terrifying, look at psychopaths: the often charming, glib, sane-seeming people who rape and murder--and rip- off S&Ls--without a second's thought because they utterly lack the emotions that add up to the defining human characteristic of conscience. Hare (Psychology/University of British Columbia) gives thumbnail sketches of one psychopath after another--from John Wayne Gacy, the serial murderer who liked to entertain children as ``Pogo the Clown,'' to mere kids who torture and kill not only animals but other children. The author isolates the essential traits of the psychopath by using a ``psychopath checklist,'' a system of assessment he's devised during ten years of clinical practice with psychopaths in Canadian prisons. Again and again, Hare's rating system has verified a definition devised in 1941 by psychologist Hervey Cleckley, who concluded that psychopaths lack all personal values: ``It is impossible for [the psychopath] to take even a slight interest in the tragedy or joy or the striving of humanity as presented in serious literature or art,'' Cleckley wrote. ``He is also indifferent to all these matters in life itself.'' Hare cites provocative new evidence that the brain function of psychopaths may differ from that of normal adults: It seems that the speech of psychopaths is controlled by both hemispheres rather than by just the left, as is typical. In addition, ``neither side of the [psychopath's brain] is typical in the processes of emotion.'' While all the implications of psychopathic brain function remain unclear, Hare makes a strong case for the view that psychopaths are born, not made--and that, crucially, little can be done to unmake them. While advocating the firm training of psychopaths to consider rationally the outcome of their actions- -substituting head for heart--the author warns that denying the incorrigible nature of these cold, calculating beings will allow even more of them to prey on society. A chilling, eye-opening report--and a call to action.