Political methodologists have long sought to develop standards that can guide political scientists in the process of concept formation. Yet, the methodology literature has struggled to provide satisfactory solutions to the fundamental problem of conceptualization: for any given concept, there are a large number of attributes one could postulate as its defining characteristics, and it is unclear how to adjudicate between different possible definitions. We leverage the fact that the theory within which a concept appears places important restrictions on concept (...) formation: conceptualizations entail ontological claims that need to be consistent with those of the theories in which they appear. (shrink)