In The Psychopath Test Jon Ronson asks, 'What if society wasn't fundamentally rational, but was motivated by insanity?'. This question led Jon on an adventure into madness, meeting psychopaths, those whose lives has been touched by madness, and those whose job it is to diagnose it. In this video Jon delivers an illuminating TED talk on what divides crazy from sane and whether there is a defining line between the two.