Abstract
Reciprocity refers to the character of the actions and reactions between two or more actors. This character is commonly one of responding in kind to the actions of another. As such, reciprocity is considered one of the fundamental processes observed by scholars in the study of international relations (IR). In the realm of international politics, the study of reciprocity typically encompasses formal/experimental and empirical research. Some scholars look at ethical dimensions and the propagation of norms such as the Golden Rule, while others undertake empirical analysis of patterns of reciprocity in search of answers to questions about the existence, predictability, and diffusion of reciprocity. As a concept, reciprocity has applications in a range of IR topics such as the basic ingredients of cooperation, the escalation and return of conflict, and the adherence to international law. Within the realm of conflict processes, the iterated Prisoner’s Dilemma (PD) and formal frameworks are often used to represent arms races and similar security concerns. Related to the iterated PD is the work of Robert Axelrod, who demonstrated the robustness of the reciprocal strategy known as tit-for-tat (TFT). One puzzle on reciprocity that deserves consideration in future research is that the expectation of a long time horizon for interaction should stimulate the incentive to cooperate, but long time horizons may also be associated with long pasts. One way to find the answer to this puzzle is to incorporate reciprocity into more general models of international interaction.