Incommensurable theories are said to be both incompatible and incomparable. This is paradoxical, because, being incompatible, these theories must have the same subject-matter, yet incomparability implies that their subject-matter is different. This paper's proposed resolution of the paradox makes use of the distinction between internal subject-matter and external subject-matter for languages (frameworks) as outlined by W. Sellars. Incommensurability arises when two languages share the same external subject-matter but differ in internal subject-matter. When they share the same external subject-matter, they can (...) be inconsistent (hence incompatible), and yet incomparable (because they are about distinct internal subject-matter). A substantial part of the paper is devoted to the technical development of the notion of inconsistency as a relationship between languages in contrast to the traditional notion of inconsistency between statements. (shrink)

This paper starts with an intuitive notion of representational spaces, which is intended to provide an improved version of Kuhn's concept of paradigms. It then proceeds to study the following topics in terms of this new notion: incommensurability, paradigm change, explanation of anomalies, explanation of regularities, explanation of irregularities, and physical necessity. In the course of the investigation, "representational space" gets clarified and defined. It is envisaged that this new concept should throw light on many issues in the philosophy of (...) science. (shrink)