many problems are caused by the mindset that the world is divided into good people and bad people and the bad people can be "found out" and removed, eventually leading to a utopia containing only good people.
"It was much better to imagine men in some smokey room somewhere, made mad and cynical by privilege and power, plotting over brandy. You had to cling to this sort of image, because if you didn't then you might have to face the fact that bad things happened because ordinary people, the kind who brushed the dog and told the children bed time stories, were capable of then going out and doing horrible things to other ordinary people. It was so much easier to blame it on Them. It was bleakly depressing to think that They were Us. If it was Them, then nothing was anyone's fault. If it was Us, then what did that make Me? After all, I'm one of Us. I must be. I've certainly never thought of myself as one of Them. No one ever thinks of themselves as one of Them. We're always one of Us. It's Them that do the bad things."
--Jingo, by Terry Pratchett
