Incommensurability and the Normative Foundations of Scientific Knowledge

Abstract

In this paper, I defend the relativity of scientific reasoning and knowledge to scientists’ diverse normative allegiances to historically variable standards of theory assessment. My aim is to justify a position of moderate relativism. This position seeks to accommodate the essential role of evidence, reasons, and reasoning in scientific choice/belief; while also giving sociological and historical factors an essential role in explaining and justifying which reasons and choices prove compelling to some scientists but not others who are equally rational and scientific. My strategy of argument is to take up the main criticisms of this sort of position in the work of post-Kuhnian writers such as Laudan, Lakatos, Siegel, Shapere, Scheffler, Sankey, and others. In particular, I examine the following influential rebuttals of relativism: (1) It is self-refuting; (2) It is refuted by the existence of rational debate in science; (3) It is refuted by the existence of neutral, external, universal standards of theory-assessment in science; (4) It is refuted by the fact that there are typically good scientific reasons for preferring some standards to others, which relativists cannot see because they embrace a misguided holistic paradigm of scientific change; (5) It is refuted by normative naturalism which provides an objective, ahistorical, and empirical method for evaluating the effectiveness of standards of scientific knowledge in attaining the aim or aims of scientific inquiry. I acknowledge the insights of these positions. But, I argue, they fail to rebut moderate relativism, and in particular, the relativity of reason and justification to diverse, historically shaped normative commitments to rival conceptions of scientific knowledge. The enduring philosophical contribution of Kuhn lies not in radical relativism, extreme incommensurability, or virulent anti-realism. Rather, it consists in the promise of a more interdisciplinary model of scientific knowledge and the logic of its growth.