What’s the difference? It’s very simple: psychopaths don’t feel guilt about hurting other people, but sadists take active pleasure in committing horrors that civilized people can’t even look at. In his pornographic novels the Marquis de Sade wrote about taking sexual pleasure from torturing and even murdering innocents. That is where we get the term “sadism.” *** ISIS is a sadistic war cult. It attracts people who take joy in torturing women and children. You can easily see the difference in their facial expressions. Psychopaths have “flat” expressions, like Vladimir Putin. Sadists show a kind of demonic joy when others...