Chapter 5 Conceptual Change and Scientific Realism: Facing Kuhn’s Challenge Theodore Arabatzis Introduction The impact of Thomas Kuhn’s work on history and philosophy of science has been unpar- alleled. His classic The Structure of Scientific Revolutions (Kuhn, 1970) has changed per- manently the historiographical and philosophical landscape. Its influence on historians of science has been pervasive but, for the most part, indirect. It is a striking fact that very few historians have employed the conceptual apparatus of The Structure (i.e., “paradigm”, “normal science”, “crisis”, “revolution”, “gestalt switch”, “incommensurability”) to illumi- nate past scientific developments. Philosophers of science, on the other hand, have been directly affected by Kuhn’s historical philosophy of science and have debated endlessly the issues that he and his fellow traveler Paul Feyerabend raised. Those issues (e.g., the ration- ality of theory-choice, the reality of the ontology of science) remain at the forefront of con- temporary philosophical reflection on science. One of the most far-reaching claims of Kuhn and Feyerabend concerned the nature of scientific concepts. They promoted a contextual view of concepts, according to which con- cepts obtain their meaning from the theoretical framework in which they are embedded. It follows that when a theoretical framework changes the concepts embedded in it change too (Feyerabend, 1962; Kuhn, 1970). Given that theory change has been quite common in his- tory of science, conceptual change must have been a ubiquitous phenomenon. Several problematic philosophical consequences seemed to ensue from conceptual change, most notably a relativist view of theory-choice and an anti-realist stance toward the ontology of science. It was widely believed that rational choice between scientific theories could take place only against a stable, shared conceptual framework. With such a framework in place the claims of competing scientific theories could be formulated in a common language and then subjected to comparative evaluation. On the other hand, in the absence of such a framework objective theory-choice seemed impossible, since there would be no common language for formulating and comparing rival scientific theories. Furthermore, the realist requirement for a stable scientific ontology was hard to reconcile with conceptual change. Reframing the Conceptual Change Approach in Learning and Instruction Copyright © 2007 by Elsevier Ltd. All rights of reproduction in any form reserved. ISBN: 0-08-045355-4