Empiricism as a Rhetoric of Legitimation: Maupertuis and the Shape of the Earth

Abstract

In the first half of the eighteenth century, Newton is slowly establishing himself on the European continent. Pierre-Louis Moreau de Maupertuis is seen as his first French disciple. Struck by the rigor and the validity of the law of attraction, he seeks a way to defend it against its detractors. He thus begins working on the polemical issue of the earth’s shape. While Cartesians thought the earth was flattened at the equator, Newton suggested it was flattened at the poles. Assessing the importance of experiments and observations, in 1736–1737 Maupertuis prepares an expedition to Lapland to prove that the earth is indeed oblate and not elongated. In his accounts of the expedition he develops something that can be called a rhetoric of empiricism emphasizing practices of replication and reproducibility. In this paper, I intend to show first how Maupertuis not merely adopted Newtonian ideas but also appropriated and transformed them. We will then see how the observations of the expedition were strongly criticized after the report was published. Some readers highlighted the limits of empiricism and raised the issue of the observations being burdened by theories. Maupertuis developed various strategies to counter attack and defend the reliability of the expedition’s results. This paper challenges the traditional interpretation of the expedition as a mere battle for Newtonianism while developing an entangled history of empiricism. The establishment of empirical science in early modern Europe was the result of a dialog combining different empirical traditions including but not limited to rational mathematical-geometric reasoning.