The observational-theoretical distinction has played a central role in the philosophy of science from logical empiricism onwards. Developments within the discipline have shown that such a distinction hides two non-identical distinctions: observational vs. non-observational and theoretical vs. non-theoretical. Likewise, metatheoretical structuralism proposed a more sophisticated treatment of theoricity in terms of the operational dependence or independence of concepts from the theories in which they appear. Despite this remarkable sophistication, it is still generally accepted that the distinction between theoretical and non-theoretical (...) concepts coincides with the explanatory vs. non-explanatory and testing vs. non-testing distinctions. Ginnobili and Carman argued for the independence between theoricity and explanation. In this paper we will focus on testing and argue for its independence from both theoricity and explanation. To do so, we propose an account of theory testing based on the framework of metatheoretical structuralism and apply it to natural selection theory and cladistics. (shrink)

A given explanatory theory T falls into circular reasoning if the only way to determine its explanandum is through the application of T. To find an underlying theory T′ that determines T′s explanandum helps us save T from this accusation of circularity. We follow the structuralist view of theories in presenting and dealing with this issue, by applying it to particular theories. More specifically, we focus on the relationship between the Darwinian theory of common ancestry and the determination of homologies.