One promise of the behavioral revolution was that metaphysical assumptions would be minimized, if not eliminated, in political research and theorizing. Nothing would be taken for granted. It is now obvious that this is not possible. Instead, the question is which metaphysical assumptions are most felicitous and persuasive in our search for knowledge about politics. This question does not have a single, uncomplicated answer. For those of us who teach research methodology, interesting and at times disillusioning developments have influenced thinking about research methodology during the last twenty years. Developments in modern logic, continental and neo- Marxist thought, philosophy of language, philosophy of science, and even literary criticism has upset previously held assumptions about behavioral political research and the nature of empirically based theory.