In both experimental and natural settings incentives sometimes under-perform, generating smaller eects on the targeted behaviors than would be predicted for entirely self-regarding agents. A parsimonious explanation is that incentives that appeal to payo maximizing mo- tives may crowd out...

Some philosophers and social scientists have stressed the importance for good government of an altruistic citizenry that values the well being of fellow citizens. Economists, however, have emphasized the need for incentives that induce even the self-interested to contribute to the public good....