Rational Choice Theory

International law scholarship has predominantly been doctrinal in nature. Nevertheless, international law and rational choice assumptions have been closely connected for a long time. For the most part, realist thinkers in international relations are the ones who have used rational choice assumptions to explain states' behavior (though [liberal] institutionalist thinkers have done so as well), but they have rarely entered into legal intricacies. Instead, "big theories" have been at the forefront of the discussion. Economics is the study of rational choice. The rational choice approach to international law allows for theoretical conjectures that can be tested empirically regarding two questions: What are the effects of international law (international law as explanans; this question includes its effectiveness)? Why do states legalize their relations (international law as explanandum)? The rational choice assumption has been a cornerstone of positive economics and economic analysis of law, which applies economic methods to analyze law. International law is a rather young subject of economic analysis of law, but it has gained prominence since 2000. Following the traditional international law assumptions in the aftermath of the Westphalian peace, the nation-state has mostly been analyzed as a unitary actor, or what has been described as a "black box" state, but in the discussion on international governance this has also changed recently. Analyzing international law through the rational choice perspective has become a joint enterprise by economists, international lawyers, and rational-choice political scientists, focusing on more precise questions of international law scholarship intended to inform doctrinal scholarship as well. Rational choice analysis may be used to diagnose substantive problems and frame better legal solutions, explain the structure or function of particular international legal rules or institutions, and reconceptualize or reframe particular institutions or international law generally, such as customary international law. It is well acknowledged that legal scholars alone cannot accomplish these tasks, and that social science approaches are needed to address them. By now, many international relations scholars, as well as law and economic scholars, start from a rationalist assumption but do not exclude other explanatory factors used by other theories. The scholarship is US-driven, and English is the main language in which research on the topic is published.