Think of the lack of empathy. Simon Baron-Cohen, the developmental psychologist, has argued that this is what lies behind the most cruel human acts. There may be many social and environmental factors that lead someone to have “zero negative” empathy, as he puts it, and then further circumstances that precipitate the violence.
But what lies at the heart of such personalities is a deficiency. It is frightening to witness. Like the zombies of old movies, there is no reasoning with such people because there is no place inside them for such reasoning to land. Empathy has no hold on them either, as it does the vast majority, because it never had the chance to take root in their psyches and grow.
by Mark Vernon