There is no doubt that cooperation problems such as incentives to cheat, uncertainty about other states’ true intentions, and struggles for power pervade the international system. States have different, often dramatically divergent, interests and seek advantage over one another. States also want to capture the benefits of cooperation, but, as the Mearsheimer quote makes clear, the obstacles (what I call “cooperation problems”) are severe.

This book argues that international law can solve these kinds of problems. More to the point, the fine-grained design provisions of international law, when chosen optimally, help states solve such problems in the international environment – problems that, if unheeded, could diminish international cooperation or prevent it altogether. Straightforward design provisions like on-site inspections to monitor compliance with a treaty's terms, or escape clauses to allow states to deal with unpleasant surprises, allow states to realize common interests and achieve a Pareto-improving cooperative outcome.

Still, in the words of Krasner (1991), winding up somewhere on the “Pareto frontier” can involve tough bargaining. That is, depending on the circumstances, states may fight hard over both substantive and design provisions before reaching the Pareto-improving outcome. Indeed, choosing the detailed design provisions of treaties is often a form of political interaction in which states maneuver and bargain for their interests. Why? Because international agreements and their design provisions are consequential.

COIL's basic theoretical premise is that the key to understanding international agreement design and to making comparisons across agreements, including across issue areas, is a focus on the underlying cooperation problem(s) the agreements are trying to solve and the underlying characteristics of the states involved in the cooperative endeavor – that is, properties that describe the set of actors in the aggregate. For example, some issues, like trying to ban chemical weapons or trying to encourage the rights of women, pose huge information obstacles: How can one state know what other states are doing?