Induction and Deduction in International Relations: Squaring the Circle between Theory and Evidence

International Relations (IR) scholarship represents the pursuit of theory about how the world works or ought to work. Yet despite this broad orientation of the field, the process of theory building itself remains challenging. There is abundant professional guidance on how to refine and test a theory once it has been created, but how do we get from a vague interest in some area of IR to a specific argument that explains or interprets a particular aspect of international politics? This article aims to refine the theorization challenge by taking stock of—and advancing—the debate over the relationship between inductive and deductive inference in IR theory building. It begins with an analysis of the short shrift still given to induction by many in the positivist IR community—a tendency that follows from the criticism of inductive theory building contained in Kenneth Waltz’s 'Theory of International Politics' (1979) and its enduring legacy, despite Waltz’s own professedly non-positivist approach—before progressing to consider the limits of a purely deductive approach to theorization. The article concludes that “creative-deductive” theory possesses key strengths, including its parsimonious and generalizable explanatory reach, and its truth-preserving quality. However, given the endogenous feedback relationship that exists between theoretical premises and empirical evidence, the paper argues that it is only once we accept that induction is an intrinsic and unavoidable component of IR theory building that we can truly seek answers to the most important questions of international politics. Accordingly, IR scholars should strive to use the two in tandem as they set about developing new theory.