Studies on hunter-gather societies suggest that people have a tendency to act for the greater good, rather than for their own immediate personal interests, as was long assumed. Moreover, experiments in economics have demonstrated that people often prefer win/win situations over outcomes in which they win and another loses. People often make generous offers when they could be selfish, reject “unfair” offers even if it means losing resources, share when they do not need to, and contribute to public goods even when they could get away with not giving anything. We believe in a better world — and we tell others about it. Every day millions of sermons are delivered about how we ought to act.