Is There a Broader-Deeper Trade-off in International Multilateral Agreements?

It is commonly thought that there is a trade-off between the breadth and depth of multilateral institutions—that is, multilaterals that are more inclusive in their memberships will necessarily be shallower in their level of cooperation. Using a multilateral bargaining model with self-seeking rational actors, I show that such a trade-off does not exist for a broad class of multilateral cooperation problems. The conclusion that there is a broader-deeper trade-off follows from the assumption that the members of the multilateral must set their policies at an identical level. The multilateral agreement modeled in this article allows states to set their policies at different levels. Once this change is made, there is no broader-deeper trade-off, a finding that has obvious empirical and policy implications. It explains why some regimes are created with fairly large memberships at the outset, and it calls into question the policy prescription of limiting membership of multilateral institutions to a small group of committed cooperators for the class of cooperation problems modeled in this article.I am indebted to the editor, an anonymous reviewer, Bruce Bueno de Mesquita, William Clark, Eric Dickson, Catherine Hafer, Charles Holt, Marek Kaminski, Dimitri Landa, Antonio Merlo, Robert Powell, Adam Przeworski, Ann Sartori, Shanker Satyanath, Randall Stone, and the participants at seminars at Rutgers and University of California-Berkeley in May and October 2000, respectively, for comments on earlier drafts of this work. I thank Jon Preimesberger for editorial assistance. All errors remain my responsibility.