In Real Life, seeing the world in absolute Black and White Morality is considered normal for small children, but seen as a far less healthy trait in adults. A person who regards the people around him as entirely good or entirely evil, as if they were part of some really simplistic narrative, is very likely to have a mental disorder. Some authors have picked up on this, playing belief in Black and White Morality as a sign of the character being insane or at least mentally unstable. Compare Activist Fundamentalist Antics, Windmill Crusader, With Us or Against Us.