World Politics

Research Article

Counterfactuals and Hypothesis Testing in Political Science

James D. Fearona1*

a1 Candidate in Political Science at the University of California, Berkeley


Scholars in comparative politics and international relations routinely evaluate causal hypotheses by referring to counterfactual cases where a hypothesized causal factor is supposed to have been absent. The methodological status and the viability of this very common procedure are unclear and are worth examining. How does the strategy of counterfactual argument relate, if at all, to methods of hypothesis testing based on the comparison of actual cases, such as regression analysis or Mill's Method of Difference? Are counterfactual thought experiments a viable means of assessing hypotheses about national and international outcomes, or are they methodologically invalid in principle? The paper addresses the first question in some detail and begins discussion of the second. Examples from work on the causes of World War I, the nonoccurrence of World War III, social revolutions, the breakdown of democratic regimes in Latin America, and the origins of fascism and corporatism in Europe illustrate the use, problems and potential of counterfactual argument in small-N-oriented political science research.

James D. Fearon is a Ph.D. candidate in Political Science at the University of California, Berkeley. His dissertation examines the question of when threats used in international crises deter and when they provoke.

* Prepared for delivery at the Annual Meetings of the American Political Science Association, San Francisco, August 30-September 2, 1990. For helpful comments and advice I wish to thank Chris Achen, Robert M. Adams, David Collier, Russ Faeges, Don Green, Marcus Kurtz, Jim Mahon, Merrill Shanks, Laura Stoker, Arun Swamy, and an anonymous referee. I am particularly indebted to David Collier for his encouragement and close reading of several drafts. None mentioned (or unmentioned) are responsible for my mistakes.