In the policy debate, intellectual property is often justified by what seems to be a straightforward argument: if innovators are not protected against others appropriating their ideas, incentives for innovation are suboptimally low. Now, in most industries and for most potential users,...

Empirically, the commons are not as tragic as standard theory predicts. The predominant explanation for this finding is conditional cooperation. Yet many real life situations involve insiders, who are directly affected by a dilemma, and outsiders, who may be harmed if the insiders overcome the...

If two players of a simultaneous symmetric one-shot prisoner's dilemma hold standard prefer-ences, the fact that choosing the cooperative move imposes harm on a passive outsider is imma-terial. Yet if participants hold social preferences, one might think that they are reticent to impose harm on...