Reception of Isaac Newton in the Scottish Enlightenment: causation, gravitation, and the transformation of natural philosophy

Abstract

This dissertation presents a new account of the reception of Isaac Newton (1643–1727) in Scotland centred on his readers and the texts that engage most explicitly with his example. It argues that the catalytic influence of Newton’s physics – through, above all, his treatment of gravitation in the Philosophiae Naturalis Principia Mathematica (1687) – helped to bring about a transformation in natural philosophy during the eighteenth century. Newton has long been considered a pivotal figure in the history of science and philosophy whose revolutionary approach to natural inquiry marked the culmination of the Scientific Revolution and gave inspiration to the philosophers of the Enlightenment.

Scholars have hitherto argued that the ‘Newtonian Revolution’ made early and enthusiastic converts in Scotland, where devoted ‘Newtonians’ established a new scientific orthodoxy which exerted a crucial influence on eighteenth-century Scottish philosophy. This received view is however limited by an anachronistic distinction between science and philosophy and essentialised modern readings of Newton’s contribution to knowledge, obscuring both significant differences of opinion among the so-called Newtonians and important conceptual innovation in physical science that occurred in this period. By focusing on how Newton's natural philosophy was understood by his readers and the many ways his example was drawn on by both admirers and critics, this dissertation shows how Newton’s reception animated and shaped important debates in the Scottish Enlightenment that cut across several fields. In so doing, it situates this reception in intellectual contexts that best reflect the interests and concerns of the actors under investigation, challenging the established narrative of the rise of Newtonianism in Scotland and typical conceptions of the Scottish Enlightenment. This study demonstrates how Scottish authors engaged with Newton’s example, in service to different ends and in diverse settings, to explain why he was so admired and how Scottish natural philosophy underwent profound change following the publication of the Principia.

Chapter 1 shows how Archibald Pitcairne (1652–1713) and George Cheyne (1671/2–1743) drew on Newton's approach to philosophy to develop controversial reform programmes for medicine that provoked fierce debate among members of the Royal College of Physicians of Edinburgh in the 1690s and early 1700s. Chapter 2 examines how David Gregory (1659–1708) and John Keill (1671–1721) contemporaneously developed a Newtonian pedagogy at Oxford primarily designed to introduce students to Newton’s approach to explanation in physics and astronomy, emphasising its superiority over errant ancient and modern philosophical traditions. While Pitcairn and Gregory stressed Newton's causal agnosticism, Cheyne, Keill, and others soon began to characterise the law of gravitation as God’s direct action in nature. Chapter 3 highlights the importance of Newtonian natural theology and traces debates over divine agency in natural philosophy through the work of Cheyne, Andrew Baxter (1686/7–1750), and Colin Maclaurin (1698–1746), in which differences of opinion are best understood in the context of broader contemporary theological debates in Scotland. Chapter 4 shows how the understanding of Newton’s method of discovery shifted around mid-century under the influence of the ‘Science of Man’ of David Hume (1711–76) and Adam Smith (c. 1723–90) and the Common Sense philosophy of Thomas Reid (1710–96), with the power of imagination and the role of inductive inference given relatively greater weight than mathematics and deductive reasoning, leading to new theories of philosophical genius developed by Alexander Gerard (1728–1795) and William Duff (1732–1815) that took Newton as a major source. Chapter 5 argues that, following these developments, natural philosophy was redefined as a more strictly empirical enterprise, particularly in reaction to the sceptical empiricism of Hume and Henry Home, Lord Kames (1696–1782) and the perceived threat of atheism and deism to which it was connected. Newton’s reputation was remade from around the 1770s, with James Burnett, Lord Monboddo (c. 1714–1799) and Edinburgh professors like John Robison (1739–1805), John Playfair (1748–1819), and Dugald Stewart (1753–1828) viewing him not as having revealed divine action in nature but as having established ‘facts’ or natural laws that did not, strictly speaking, describe actual physical processes. Though there were disagreements about the precise nature of Newton’s own philosophical practice, his example shaped a new vision of natural philosophy established around the turn of the nineteenth century at Edinburgh by Robison, Playfair, Stewart, and others. This new ideal fed in to influential biographies of Newton written by an Edinburgh alumnus, David Brewster (1781–1868), and did much to shape the identity of the nascent natural sciences in Britain in the early nineteenth century.