Newton, Isaac (1642–1727)

Isaac Newton is best known as a mathematician and physicist. He invented the calculus, discovered universal gravitation and made significant advances in theoretical and experimental optics. His master-work on gravitation, the Principia, is often hailed as the crowning achievement of the scientific revolution. His significance for philosophers, however, extends beyond the philosophical implications of his scientific discoveries. Newton was an able and subtle philosopher, working at a time when science was not yet recognized as an activity distinct from philosophy. He engaged with the work of Rene Descartes and G.W. Leibniz, and showed sensitivity to the work of John Locke, Francis Bacon, Pierre Gassendi and Henry More, to name just a few. In his time, Newton was not perceived as a scientific outsider, but as an active and knowledgeable participant in philosophical debates. Nevertheless, Newton’s work helped precipitate the separation of physics from philosophy. The Principia defined a programme for physical research that persists to this day, but its early reception, particularly among Cartesians and Leibnizians, was difficult. To defend this programme from criticism, Newton and his successors portrayed their work as essentially autonomous from the philosophical demands of their contemporaries, thus creating modern science. Even without the Principia, Newton’s place in history would have been guaranteed by his work in optics and mathematics. Newton discovered that white light was composed of rays from the entire visible spectrum and ingeniously measured a microscopic property of light that he called ‘fits’, a forerunner to our ‘wavelength’. His work in pure mathematics was ground-breaking: he invented the calculus (independently of Leibniz) and advanced both algebra and analytic geometry. His overall success in natural philosophy, which in his hands was applied mathematics, was largely due to his unparalleled skill as a mathematician. Newton also engaged in activities that belong to neither modern science nor modern philosophy. His work on biblical chronology, interpretation of ancient prophecies and alchemy took up much of his intellectual efforts, but this work was largely ignored in the century after his death by an Enlightenment ideology occupied with painting its own past. Newton was partly responsible for this historiographical blindspot. He kept most of his ‘esoteric’ beliefs, such as his rejection of the Trinity, hidden. He promoted a public image that placed him in the tradition of Galileo and Huygens, figures more narrowly focused on physico-mathematics than he was.