International Relations Theory

International relations (IR) theory is difficult to define. It is often taught as a theory that seeks both to explain past state behavior and to predict future state behavior. However, even that definition is contested by many theorists. Traditional IR theories can generally be categorized by their focus either on humans, states, or on the state system as the primary source of conflict. Any bibliography of international relations theory is bound to create controversy among its readers. Why did the author choose one theory and not the other? Why did the author choose one source and not the other? Indeed, a wide variety of permutations would be perfectly valid to provide the researcher with an adequate annotated bibliography, so why were these particular entries chosen? This article identifies Realism, Liberalism, and Constructivism as the three major branches of IR theory. These three branches have replaced the earlier realism-idealism dichotomy. The “English School” could be considered part of any of the aforementioned three branches, and its placement in the IR theory world is the subject of some debate. It has therefore been given its own section and is not included in any of the other sections. Critical IR theory and Feminist IR theory are often considered part of constructivism; however, there is much debate over whether they constitute their own branches, and so they are included in this article (as well as in their own entries in the OBO series), though the sources are somewhat different. Post–Cold War IR Theory is given its own heading because there are a number of theories that were proposed in the immediate aftermath of the Cold War that are still widely taught and discussed in the field. Perhaps the most controversial inclusion is that of Neoconservatism. Though it is quite possible to mount a case for it to be considered a theory of US foreign policy, it is theoretically distinct from other IR theories (the belief in bandwagoning instead of balancing). The final three sections are included to show how political theory has influenced IR theory, and how history and foreign policy have influenced IR theory (and vice versa). The included sections and citations represent both the mainstream of IR theory and those nonmainstream theories that have just started to break into the mainstream of IR theory. This article provides a starting point for both the beginning and the serious scholar of international relations theory.