Newtonianism in the French Enlightenment

Rob Iliffe is Professor of Intellectual History and the History of Science in the Department of History at the University of Sussex. He has written the Very Short Introduction to Newton and directs the online Newton Project. On 28 February 2015 he gave a fascinating talk at the ‘Voltaire and the Newtonian Revolution’ conference that explored the fate and legacy of Newton’s scientific views in eighteenth-century France of which this is a brief summary.

Newton_frontispiece

Soon after Newton had published his initial work on the heterogeneity of white light (in 1672), he became embroiled in a series of disputes about the truth of his theory, and about the facts on which it was based. Edme Mariotte’s failure to reproduce aspects of Newton’s ‘crucial experiment’ in 1681 influenced the negative opinion of Newton’s work by many French physicists, although there was increased interest in his work at the Académie des Sciences following the publication of his Optice in 1706. There was also opposition to the physical theories and epistemological claims expressed in his Principia Mathematica, and many commentators continued to prefer the Cartesian doctrine of tourbillons to the notion of ‘attraction’ that underlay Newton’s theory of universal gravitation.

Pierre Louis Moreau de Maupertuis (1698-1759). Source gallica.bnf.fr / Bibliothèque nationale de France

Pierre Louis Moreau de Maupertuis (1698-1759). Source gallica.bnf.fr / Bibliothèque nationale de France

A delegation of French natural philosophers visited England in 1715 and were treated to a number of experiments that confirmed Newton’s theories. However, it was Newton’s death in the spring of 1727, and Bernard de Fontenelle’s influential Eloge that followed, that triggered a serious spurt of interest in his work. Two men, Voltaire and Pierre Moreau de Maupertuis wrote popular works in the early 1730s that brought the nature and revolutionary scope of Newton’s ideas to a much larger audience. Yet it was not until the results of a French scientific expedition to Lapland were announced in 1737 that the public really began to switch allegiance to the Newtonian worldview. This excursion, led by Maupertuis, left France in 1736 to measure the length of a degree, one year after another voyage had set out to perform similar cartographic measurements in Peru (now Ecuador). The results from the Finnish expedition, and indications from the ill-fated trip to Peru, showed that the earth was flattened at the poles (as Newton had argued), and was not a prolate spheroid as many Cartesians had claimed.

Newtonianism was duly adopted and made the central plank of their paean to Enlightenment by men such as Voltaire and Jean Le Rond D’Alembert. Newton’s attacks on arbitrary and fictitous ‘hypotheses’ and ‘systems’ were reconfigured to serve in the general assault on the ‘infamy’ of persecution and superstition. There were some problems with the approach, firstly because Newtonianism could be used (as the British largely did) to defend the idea of an intelligent Creator God, and secondly because Newton himself was clearly both devout and a serious student of theology. While the latter could be explained away as the result of senility or dilettantism, there was always the danger that Newton himself could be deified as the founder of Reason. This possibility was explored in the majestic designs for a Cenotaph to Newton created by Etienne-Louis Boullée in the mid-1780s, and in the early plans for a ‘Church of Newton’ described by Henri de Saint-Simon at the start of the following century.

– Rob Iliffe, Director of the Newton Project

Cross-section of a ‘Newton cenotaph’ by Etienne-Louis Boullée. Source: gallica.bnf.fr / Bibliothèque nationale de France

Cross-section of a ‘Newton cenotaph’ by Etienne-Louis Boullée. Source: gallica.bnf.fr / Bibliothèque nationale de France

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