 Feyerabend used the idea of incommensurability to attempt to expose a dogmatic element that contemporary empiricists share with school philosophies such as Platonism and Cartesianism (from whom empiricists had tried to distance themselves by insisting on an empirical foundation for scientific knowledge). The dogmatic element is due to the assumption that the meanings of empirical terms remain stable through theoretical transitions; or what Feyerabend called the principle of meaning invariance (1962, 30). Feyerabend argued that this principle is inconsistent with the existence of incommensurable concepts. Feyerabend drew two main consequences from the insight that some pairs of successive scientific theories are incommensurable. First, successive scientific theories that are incommensurable have no logical relations: “The order introduced into our experiences by Newton’s theory is retained and improved by relativity. This means that the concepts of relativity theory are sufficiently rich to allow us to state all the facts which were stated before with the help of Newtonian physics. Yet these two sets of categories are completely different and bear no logical relation to each other” (1962, 88–89). Because their concepts have different meanings, they cannot be brought into formal logical relations. Second, a revision in the logical empiricist conception of scientific advance is required. Older theories, and the concepts used to state them, are not corrected and absorbed, and thereby legitimised. Rather, they are rejected and replaced, having been falsified. In this way, the logical empiricists’ conceptually conservative (or retentive) accounts of reduction and explanation are undermined. They cannot accommodate the development of incommensurable concepts in the course of scientific advance.