"We all know what it feels like when the moralization switch flips inside us — the righteous glow, the burning dudgeon, the drive to recruit others to the cause. The psychologist Paul Rozin has studied the toggle switch by comparing two kinds of people who engage in the same behavior but with different switch settings. Health vegetarians avoid meat for practical reasons, like lowering cholesterol and avoiding toxins. Moral vegetarians avoid meat for ethical reasons: to avoid complicity in the suffering of animals. By investigating their feelings about meat-eating, Rozin showed that the moral motive sets off a cascade of opinions. Moral vegetarians are more likely to treat meat as a contaminant — they refuse, for example, to eat a bowl of soup into which a drop of beef broth has fallen. They are more likely to think that other people ought to be vegetarians, and are more likely to imbue their dietary habits with other virtues, like believing that meat avoidance makes people less aggressive and bestial."