4. Heterogeneity, Linkage and Commons Problems

Like individuals facing common-pool resource problems, states search for ways to solve collective-action problems in the international system without turning to external enforcement. Heterogeneity of power and of preference intensities may enhance the probability of cooperation, if states are able to link issues credibly. International decision-making rules that require more than majority support will also increase the demand for issue linkage. Credible issue linkages are facilitated by stringent domestic ratification rules.