Really superb article in the New Yorker, you should read the whole thing:
According to Nemeth, dissent stimulates new ideas because it encourages us to engage more fully with the work of others and to reassess our viewpoints. “There’s this Pollyannaish notion that the most important thing to do when working together is stay positive and get along, to not hurt anyone’s feelings,” she says. “Well, that’s just wrong. Maybe debate is going to be less pleasant, but it will always be more productive. True creativity requires some trade-offs.”
Ducks and Economics 