The incommensurability thesis was introduced into history and philosophy of science as an integral part of the historicist views of Thomas S. Kuhn and Paul Feyerabend. Critics immediately charged that if scientific theories really were incommensurable then they could not be compared for relative cognitive merit, and a relativistic view of science results. Historical study, though, seems to support the view that there are conceptual discontinuities between such theories. For example, the medieval…
Read moreThe incommensurability thesis was introduced into history and philosophy of science as an integral part of the historicist views of Thomas S. Kuhn and Paul Feyerabend. Critics immediately charged that if scientific theories really were incommensurable then they could not be compared for relative cognitive merit, and a relativistic view of science results. Historical study, though, seems to support the view that there are conceptual discontinuities between such theories. For example, the medieval concept of impetus is not translatable into Newtonian mechanics; nor does the phlogiston concept, central to that theory of combustion, translate into the framework developed by Lavoisier. Such translations would violate the principles of the respective theories. ;The same historical studies also support the critics' view that there are large-scale continuities or overlap between the members of each pair. The difficulty is the reconciliation of the incommensurability claim with claims for continuity or overlap. In this work I argue that this difficulty is an artifact of faulty ways of looking at language. The premise I isolate holds that scientific vocabularies can be treated as single units for analysis; any change made in one part of a vocabulary necessitates changes throughout the whole. This I call semantic holism. The thesis I defend, then, is that it is not incommensurability by itself which necessitates global change but rather incommensurability conjoined with semantic holism. Relativism can be avoided by doing away with semantic holism, therefore. In offering an alternative I distinguish five categories of terms in a typical scientific theory and argue that each is changeable independently of the others; thus, change of the central, paradigmatic parts of a theory need not result in global change throughout. This allows a basis for what Kuhn has recently called local incommensurability as a thesis which suffers no danger of relativism and irrationalism. ;My conclusions, then, hold that local incommensurability is a real, historical phenomenon which must be accounted for by philosophers and historians of science; once divorced from semantic holism, though, it does not lead to disorder, relativism, or to an irrationalistic philosophy of science