The Rationality of the Copernican Revolution

Abstract

Given the central importance of the Copernican theory to the birth of modern science, it is somewhat surprising to learn that there were remarkably few committed Copernicans prior to 1600. In a recent study, Westman (1980) finds only ten, of whom fewer than five were major scientific figures. The vast majority of scientists in this period continued to accept the Earth-centered astronomy of Ptolemy or later switched to the geoheliocentric system of Tychp Brahe. This widespread reluctance to adopt the heliocentric theory suggests the following questions about the Copernican Revolution: When and why did it become rational to reject the Ptolemaic theory as false? When and why did it become rational to accept the Copernican theory as true? Or, to put these questions in the more familiar language of the epistemologist: When and why did the beliefs that the Ptolemaic theory is false and that the Copernican theory is true become justified beliefs?