Abstract
Kuhn regards local incommensurability as an unavoidable result of changes in worldview, but his account fails to explain both historical cases in which rivals with different paradigms obtained consensus, and psychological experiments in which people with different cultural backgrounds accurately presented other points of view. Although the conditions required to generate local incommensurability were present in the dispute between Brewster and Herschel on light absorption, they succeeded in communicating. Ultimately Brewster understood his opponent's position, in the same way that subjects in Barsalou's recent psychological experiments proved able to comprehend alien conceptual structures. Building upon recent cognitive theories of graded conceptual structures, I offer a new account of incommensurability, which accommodates these historical cases and psychological results. By correcting and extending Kuhn's account I show that local incommensurability may be a matter of degree.