The science of Psychology, like Medicine (of which Psychiatry is
the branch dealing with the medical treatment of psychological
disorders), is after all a human endeavor, and as such it shouldn't
surprise you that psychologists routinely disagree with each other
on many aspects of psychology and psychiatry, just as doctors
routinely disagree with each other on diagnoses and best
treatments.
As shared by this Time magazine article, some psychologists are
of the opinion that Psychopaths, Sadists and Anti-Social
Personalities, are 3 very distinct type of monsters. Of course,
with something as complex as human psychology and human medicine,
it shouldn't surprise you either, that it's definitely possible
(even probable) for some individuals to be afflicted with more than
one type of disorder or disease, and indeed wouldn't it be an utter
delight to be abducted by an anti-social, sadistic, psychopath
all-rolled-into-one??
http://healthland.time.com/2012/05/14/understanding-the-psychopathic-mind/
Also check out : https://www.youtube.com/results?q=saw+movie
