Ostracism is practiced by virtually all societies around the world as a means of enforcing cooperation and excluding … contributors are excluded but also because high contributors sustain a higher cooperation level under the exclusion institution …

In evolutionary models of indirect reciprocity, reputation mechanisms can stabilize cooperation even in severe … cooperation problems like the prisoner's dilemma. Under certain circumstances, conditionally cooperative strategies, which … lead to a breakdown of this kind of indirectly reciprocal cooperation. Backward induction, however, requires strategies …