Do States Act Rationally and How Do We Know What They Think?

This essay discusses two interrelated questions that have emerged in recent international relations literature, ‘How do states think?’ and ‘How do we know what states think?’, with an empirical focus on the Indo-Pacific. Lurking behind these questions is often the assumption that states are rational actors. This essay will therefore examine the concept of rationality, the state of the art about the rationality of states, and the strategic thinking of several states in the Indo-Pacific. I argue that it is the observer’s approach to a state that determines the state’s rationality according to Mearsheimer and Rosato’s homo theoreticus benchmarks, which model states as machines and angels rather than humans. When seen as rich tapestries rather than black boxes, states in the Indo-Pacific often violate this rationality standard. Based on insights from cognitive science, I suggest some directions for rethinking the rationality of foreign policy and reconceptualising the rational actor assumption.