In standard contexts of collective action that takes the form of a large-number prisoner's dilemma exchange, however, the group cannot be trustworthy. The members of the group might well share some set of interests as, for example, the people of Los Angeles and Houston virtually all share an interest in reduced pollution in their cities. If all of them would stop barbecuing over open flames in their backyards, pollution would be significantly reduced. The interest of any given individual in these cities, however, is typically to renege on acting for the collective benefit, to free ride on the efforts of others, while barbecuing as usual. According to the logic of collective action, your own interest, as in this example, is to free ride on the efforts of others even with respect to your own personal interest in the product of group effort (Olson 1965; Hardin 1982a). Eo ipso, your interest is not likely to encapsulate mine with respect to that joint product if it does not even include your own.

DEFINE: Explains the free-rider problem in large-number prisoner's dilemma contexts: individual incentives favor reneging even when interests are shared.

Russell Hardin, Trust and Trustworthiness, loc. 810