Abstract

This work concerns two related issues about scientific progress: first, what precisely is Thomas Kuhn's incommensurability thesis and does it have merit? Second, what are some of the principal implications of this thesis for scientific rationality? It is argued that Kuhn's thesis is not so much that theories cannot be translated, as it is that certain key aspects of scientific understanding are inexpressible, and hence not comparable. Thus incommensurability means not just that the empirical results of one theory cannot be reproduced in another theory, but that the evaluative apparatus of a scientific community is not available as a set of explicit statements. This is shown to be the other side of the coin to logical positivist efforts to provide a verification criterion of meaning for theoretical terms. However, Kuhn's thesis creates a problem only for those who take scientific progress to be a matter of theory comparison. It is argued that progress can instead be understood without the need to compare theories. Kuhn's thesis leaves room to show how theories in different paradigms can still be understood as about the same topic. It is also possible to employ internal but still objective standards of evaluation to theories