Book Review: Isaac Newton and Natural Philosophy

Richard Westfall’s lengthy Never at Rest: A Biography of Isaac Newton was published about four decades ago but is still authoritative, while James Gleick’s succinct Isaac Newton is only about 15 years old. Rob Iliffe’s excellent Priest of Nature: The Religious Worlds of Isaac Newton appeared just last year. What is there to be gained from another biographical treatment of Isaac Newton? This book is for those who are interested not so much in the biographical but the intellectual details. What specific puzzles did Newton face, how did he address them, and how did they shape his overall scientific oeuvre? Guicciardini presents in a short volume what until now had been treated mainly by specialists in the history of mathematics or physics.

In the introduction Guicciardini retraces the story of Newton’s evolving relation in the light of things like the alchemical manuscripts, his fascination with Egyptian and Chaldean myths, and the dimensions of the Temple of Jerusalem, highlighting the fascinating role of John Maynard Keynes. It is tempting for Newton’s modern fans to turn our eyes away from these interests of his. But Guicciardini says, in effect, “No, wait! You miss how it all happened!” His approach, he tells us, is to show how Newton wasn’t spinning ideas out of his head but confronting problems that nagged his contemporaries. This approach makes Newton harder to understand. “[W]e should not think that the ‘traditional’ Newton, the mathematician and physicist, is less remote to us than Newton the alchemist and theologian” (21). But the reward is a better grounded picture of Newton, and history of science.

Guicciardini reveals, for instance, the extent to which Newton’s interest in mathematics was driven by practical concerns. “Too often,” he writes, “we look at Newton as a natural philosopher whose thought flew high above the needs of mankind, and tend to underestimate how seriously he took the practical needs of the world of the so-called ‘mathematical practitioners’ such as gaugers and surveyors” (47). Such practitioners posed the grand challenges for ambitious young scholars of the day, and Newton tackled them by introducing novel mathematical conceptions of the infinite and the infinitesimal. Guicciardini is good at conveying the complex story of the origins of calculus; for each of its founders it was something a little different. “[W]e should conceive the discovery of calculus as a long process, at least spanning the period beginning with Pierre de Fermat and Kepler and culminating with the work of Euler” (49). Understanding this allows one to understand better Newton’s anxieties when it came to publishing his discoveries.

Guicciardini’s view-from-the-ground also helps to develop a greater appreciation of Newton’s optical and telescopic work, and what made these so controversial in Newton’s lifetime. It also helps to understand what was at stake in the contemporary controversies over Newton’s mechanics, and why it appeared so implausible to many followers of Descartes. The more remote, in Guicciardini’s hands, that Newton may appear to us as a mathematician and physicist, the better we are able to appreciate Newton’s reasoning, and hence expertise as a scientist. Guicciardini’s approach is especially effective when it comes to Newton’s alchemical writings. He warns against the ‘Da Vinci Code effect,” a Janus-face image of Newton’s thinking, in which there is the scientist on the one hand and the practitioner of esoteric knowledge on the other. Newton was simply trying to make the best sense he could of things using all the intellectual tools at his disposal.

I also found refreshing remarks such as that “the Principia is written terribly” (150). Fortunately, Guicciardini is there to read and condense it for us, and put it in context. It was enlightening, too, to be told that Newton’s “involvement in philosophical issues was defensive in nature,” and did not stem from a spontaneous interest in them but arose from “his need to defend his mathematical and experimental edifice from criticisms,” above all from Leibniz (179). “We get the impression that philosophy was for Newton a necessity rather than a vocation, a defensive strategy rather than a chosen line of research” (180). Guicciardini’s book is a model for how to approach the work of an innovator like Newton not only historically but also philosophically.

The articles in this issue represent the views of their authors and are not necessarily those of the Forum or APS.