ABSTRACT
To what extent are enforcement mechanisms necessary for multilateral environmental agreements (MEAs) to be effective? International Relations scholars disagree on this question. Meanwhile, economic laboratory experiments show that enforcement mechanisms have a large and significant positive effect on cooperation among individuals. Notably, the observed effect violates predictions based on the standard assumptions of rational choice theory. The effect is consistent with strong reciprocity: a cooperation-enhancing force defined as “a predisposition to cooperate with others, and to punish (at personal cost, if necessary) those who violate the norms of cooperation, even when it is implausible to expect that these costs will be recovered at a later date” (Gintis et al. 2005: 8). In other words, strong reciprocators are willing to sacrifice resources both to be kind to those who are being kind (strong positive reciprocity) and to punish those who are being unkind (strong negative reciprocity) (Fehr et al. 2002). Concerning institutional design of MEAs, a recent experiment (Aakre et al. forthcoming – henceforth referred to as AHH) suggests that enforcement of compliance is effective if, and only if, participation is also incentivized. This chapter develops an agent-based model (ABM) of strong reciprocity that explains the collective outcomes observed in public good games with punishment. This model is then used to test the robustness of the conclusions drawn from the experiments. This analysis indicates some conditions under which international environmental cooperation will likely occur, given that some states act according to the principle of strong reciprocity.
