Add to ORKGABSTRACT: I discuss in a systematic order the most important epistemological positions in the instrumentalism-realism debate, viz., instrumentalism, constructive empiricism, referential realism, and theory realism. My conclusions are as follows. There are good reasons for the instrumentalist to become a constructive empiricist. In turn, the constructive empiricist is forced to become a referential realist in order to give deeper explanations of success differences. Consequently, there are further good reasons for the referential realist to become a theory realist. The nature of proper theories, that is, theories using theoretical terms, or rather the attitude one should have towards them is the subject of the ongoing realism-instrumentalism...