Leadership and the aggregation of international collective action

Political entrepreneurs, or leaders, play an important role in overcoming under-provision and coordination problems inherent in international public goods. Recent examples include the Montreal protocol on ozone depletion and NATO peacekeeping. We demonstrate that the Prisoner's Dilemma need not be a fait accompli of international collective action, owing to the various means for aggregating contributions (summation, best shot, better shot, weakest link and weaker link). Using evolutionary game theory, we examine 'leading by example,' whereby a leader unilaterally provides an intermediate contribution, and matching behavior there beyond. it is shown to be a noncooperative means for achieving cooperative provision.