Multilateral Cooperation in an Iterated Prisoner's Dilemma

There is a remarkable consensus among scholars of international relations that bilateral cooperation is easier to achieve than multilateral cooperation. This essay proposes a formal model to show that this is incorrect, because a multilateral agreement may achieve what an equivalent series of bilateral agreements cannot. The author explores formally several different enforcement mechanisms, suggesting that the argument is robust. Throughout the essay, the author uses examples from the Marshall Plan to illustrate the logic of this result. The argument has implications for other substantive topics, such as most-favored-nation clauses in trade agreements, the theory of hegemonic stability, analysis of the European Economic Community, the politics of linkage, and the study of multilateralist norms.