JAMES HUTTON’S THEORY OF THE EARTH AND HIS CONCEPT OF TIME: THE TIME OF LEIBNIZ, NOT THAT OF NEWTON

In his Theory of the Earth (1795), James Hutton expanded his earlier (1788) account of processes by which the Earth’s crust and its topography have been modified over the course of geologic time, the great span of which was by then becoming apparent. Drawing on detailed field observations, Hutton developed what we would now call a ‘dynamic steady state model’ of the Earth’s operation. Sediments derived from eroding mountain ranges accumulate in adjacent basins, subsiding to great depths, where the Earth’s internal heat causes them to be lithified and then uplifted to form new mountains. Hutton demonstrated for the first time that the rocks of the Earth’s crust record multiple cycles of mountain building and destruction by erosion.

The parallel between Hutton’s cycles of mountain building and erosion, perennially renewing the fertility of the soil, and Isaac Newton’s explanation of planetary motions in terms of the law of gravity has been widely recognized. To these deists, the law-abiding cycles of planetary motion and the more or less regular repetition of rock sequences were propitiously adjusted by an omnipotent Creator, to ensure the harmonious operation of the natural world. Newton is one of the few authorities cited in Hutton’s book. However, it seems not to have been appreciated that Hutton’s view of time itself was not that of Newton, but rather that of his great rival, Gottfried Wilhelm Leibniz. Newton, setting time itself apart from the relative time of human experience, famously asserted that “Absolute, true and mathematical time, of itself, and from its own nature flows equably without regard to anything external”. Leibniz, following Aristotle, construed time as an emergent phenomenon, linked to motion and arising from the occurrence of events in succession within the natural world. In the same vein, Hutton observed that “Time, which measures everything in our idea . . . is to nature endless and as nothing.” In other words, time exists solely by virtue of the sequential occurrence of events — in his case, cycles of mountain building and erosion — in the real world. Did Hutton consciously draw on Leibniz in his thinking about time, or did both men independently hew more closely to Aristotle, whose relational view of time had been resolutely set aside by Newton? In this paper we will set out the evidence bearing on this question.