However, the application of set theory and QCA raises some approach specific issues. In this paper, I address one such issue: Which, if any, gains for the analysis of an outcome can come from PT in negative cases in set-theoretic MMR? By negative cases, I simply mean cases where the outcome does not occur. Researchers using PT often refer to negative cases when arguing why their perspectives on positive cases are valid. For instance, in her study of the 'nuclear taboo' in American foreign policy, Tannenwald (1999, 442-443) discusses the decision to bomb Hiroshima and Nagasaki (a negative case of nuclear non-use). She shows that-while some protested using nuclear weapons against Japan-moral arguments did not play the role they did in later non-use decisions. In another well-known example, Skocpol (1979) uses cases where social revolutions did not happen to support her study of the French, Russian, and Chinese revolutions. For instance, she examines why the Meji Restoration in Japan did not result in a revolution, even though it resulted in a political crisis resembling the crisis of pre-revolutionary France. She argues that Japanese bureaucratisation and the absence of a powerful landed upper class meant that Meji