Rational choice institutionalism (RCI) conceives of European integration as the outcome of three interplaying forces—interests, information, and institutions. Cooperation in the European Union (EU) is thus based on collective choices among a diverse set of actors ranging from voters to member states that disagree over the potential outcome of the decision-making process, are uncertain about the motives and resources of other players, and are exposed to decision-making rules with varying distributional consequences. RCI distinguishes between two fundamental choices the supranational organization can make. EU actors can in this perspective either decide how the EU should be governed (“decision-making about rules”) or how a policy should be changed with the help of a given rule (“decision-making within rules”). The first perspective deals largely with the intergovernmental conferences during which the European Union has changed the rules that structure the interactions among the member states. The latter viewpoint addresses how the relevant decision makers of the European Union have amended or prevented policy changes alone or in collaboration with other actors.
Both perspectives draw on the standard assumptions of the rational choice research program that actors engage into means-ends calculations in a consistent way, process new information efficiently, and are aware of the preferences and rationality of other relevant actors. This implies, in the context of EU decision-making, that the adoption of new rules and polices is the consequence of the strategic behavior of those players who possess the power to influence the collective choice. The application of the RCI approach to EU integration has resulted in a multitude of studies seeking to explain its capacity for institutional reform, policy change, or absorption of new members. While the European Parliament, like any other legislature, concludes its deliberations through voting, other EU decision-making bodies mainly decide either through bargaining or through delegating certain tasks to a subordinate actor. RCI has adopted different workhorse models borrowed from game theory to reflect the variety of decision-making modes: the spatial theory of voting, non-cooperative bargaining theory, and principal-agent models have become the standard approaches to study European integration.
RCI research has faced several challenges since becoming a mainstream approach in the study of EU decision-making. The first set of criticism focuses on the axiomatic basis of the RCI research program in general and questions its usefulness for understanding the evolution of an organization as complex and large as the EU. Other objections that are frequently raised refer to the empirical tests of the hypotheses derived from the game-theoretic models. Finally, critics of the approach question the ability of the RCI program to deal with the role of informal institutions.