(With Christian List). American Political Science Review 107(4), 629-643, 2013. Preprint PDF.
Political science is divided between methodological individualists, who seek to explain political phenomena by reference to individuals and their interactions, and holists (or non-reductionists), who consider some higher-level social entities or properties such as states, institutions, or cultures ontologically or causally significant. We propose a reconciliation between these two perspectives, building on related work in philosophy. After laying out a taxonomy of different variants of each view, we observe that (i)although political phenomena result from underlying individual attitudes and behaviour, individual-level descriptions do not always capture all explanatorily salient properties, and (ii) non-reductionistic explanations are mandated when social regularities are robust to changes in their individual-level realization. We characterize the dividing line between phenomena requiring non-reductionistic explanation and phenomena permitting individualistic explanation and give examples from the study of ethnic conflicts, social-network theory, and international-relations theory.