The mother of all isms: Causal mechanisms and structured pluralism in International Relations theory

Theorizing under the rubric of paradigmatic ‘isms’ has made important conceptual contributions to International Relations, but the organization of the subfield around these isms is based on flawed readings of the philosophy of science and has run its course. A promising alternative is to build on the philosophical foundation of scientific realism and orient International Relations theorizing around the idea of explanation via reference to hypothesized causal mechanisms. Yet in order to transform the practice of International Relations theorizing and research, calls for ‘analytic eclecticism’ must not only demonstrate that scientific realism is a defensible epistemology amenable to diverse methods; they must provide a structured and memorable framework for diverse and cumulative theorizing and research, field-wide discourse, and compelling pedagogy. I Introduce a ‘taxonomy of theories about causal mechanisms’ as a structured pluralist framework for encompassing the theories about mechanisms of power, institutions, and legitimacy that have been providing the explanatory content of the isms all along. This framework encourages middle-range or typological theorizing about combinations of causal mechanisms and their operation in recurrent contexts, and it offers a means of reinvigorating the dialogue between International Relations, the other subfields of political science, and the rest of the social sciences.