The methodology of necessary conditions

Necessary conditions provide an interesting example of a concept that everyone knows, that many people use, and yet for which no explicit methodology exists. The gap between theory and empirical testing in political science is rarely as wide as it is in the case of necessary conditions. Political science is rich in theories and hypotheses that imply necessity, but adequate empirical tests are lacking. As the concept of a necessary condition is a useful one for social scientists, methodological tools for the evaluation of necessary condition hypotheses must be developed. This constitutes our purpose. We describe appropriate procedures for the two key aspects of the empirical evaluation of necessary condition hypotheses: determining (1) whether X is a necessary condition for Y and, if so, (2) whether X is trivially necessary.