While Locke's relationship to the natural-philosophical endeavours of his time has previously been subject to academic scrutiny, it arguably has never received such a painstaking and well-structured examination as in Peter Anstey's masterful John Locke and Natural Philosophy. In fact, what makes this such an excellent study is Anstey's exacting attention to the details of Locke's writings, including the Essay Concerning Human Understanding and his medical and chymical works. Having spent quite a number of years co-editing Locke's writings on natural philosophy and medicine for the Clarendon edition of Locke's Works, Anstey is extremely conversant with the material. Indeed, the long gestation of this self-described ‘commentary’ (p. ix) is evident in his close attention to the nuances of the texts themselves. While he adeptly contextualizes Locke's natural-philosophical ideas, Anstey never strays too far from the texts; given the plethora of already extant studies concerned with this subject, this is a good thing, as John Locke and Natural Philosophy provides both well-needed clarification and fresh insights. As a result, Anstey cuts through what has become something of a Gordian knot of contradictory evidence and opinion, and in so doing provides us with as clear a picture as can reasonably be hoped for.

John Locke and Natural Philosophy consists of four central theses: foremost, that Locke emphasized the utility of experimental philosophy and was pessimistic regarding speculative systems; second, that Locke believed a truly demonstrative natural philosophy was beyond our cognitive grasp; third, that Locke, despite his criticisms, did engage in speculative natural philosophy, e.g. chymistry; and lastly, that Locke changed his views regarding natural philosophy after the publication of Newton's mathematical method in the Principia. While each thesis is, in turn, well argued, it seems to me as though Anstey's most forceful is the first, namely Locke's commitment to experimental philosophy. A considerable number of chapters are dedicated to demonstrating – against the positivist placement of Locke as a precursor to the hypothetico-deductive method – that Locke championed a (quasi-Baconian) experimental philosophy that was not far removed from the ambit of the Royal Society. Indeed, Anstey illustrates how Locke believed that the most suitable method, given our cognitive limits, was the practice of natural history. Locke's indebtedness to the natural-historical method of Francis Bacon and Robert Boyle – and, perhaps most surprisingly, his interest in seventeenth-century travel literature – is consequently offered as a means to elucidate the intellectual station of the Essay.

Anstey thus situates the Essay within the context of the seventeenth century's natural-philosophical obsession with the epistemic limits of the mind. Locke, he makes clear, found intellectual coherence amongst his four ‘Master-Builders’ – Boyle, Sydenham, Huygens and Newton – precisely on account of their adherence to and practice of the experimental philosophy. The experimental philosophy provided members of the early Royal Society with what they believed to be the only means of securing the verity of knowledge about the natural world, and this is precisely where Anstey locates Locke. Locke's pessimism regarding speculative natural philosophy is underlined by the argument that the Essay – based upon the belief that the natural-historical method was the only genuine solution to our limited epistemic access to nature – represented ‘a new genre of writing experimental histories of the understanding’ (p. 225). That said, while Anstey convincingly argues for Locke as a proponent of the experimental philosophy, he is also keen to constitute evidence for Locke's growing preoccupation with the mathematical method of the Principia during the 1690s and, moreover, to do justice to Locke's interest in mercurialist transmutational chymistry.

John Locke and Natural Philosophy is a study in the history of philosophy, writes Anstey, not in the history of science (p. 1). Yet one would be hard pressed to argue that it is not just as much a history of science as it is a history of philosophy, and this intrinsic interdisciplinarity, I believe, says something about the considerable calibre of this monograph. There is a certain academic honesty at the heart of Anstey's analysis of Locke's relationship to the natural-philosophical milieu in which he lived, and it is one which secures as much objectivity as possible given the available sources. John Locke and Natural Philosophy provides a comprehensive reconstruction of Locke's writings on natural philosophy, and should not be missed by anyone with an interest in the subject.