ABSTRACT
There are many notable thought experiments in the writings of the two great natural philosophers Isaac Newton (1642–1727) and Gottfried Leibniz (1646–1716). The one most often cited from Newton’s work is his thought experiment with the rotating bucket, by which he undermined Descartes’s relational account of motion. Leibniz’s most famous work, perhaps, is the thought experiment concerning the mill given in his Monadology, which he uses to argue for the non-reducibility of perception to mechanical operations. The former still plays a seminal role in arguments about the ontological status of spacetime; the latter may be considered ancestral to John Searle’s Chinese Room thought experiment. Another of Leibniz’s work which is still very topical is the thought experiment underlying the so-called Leibniz Shift arguments, where we are asked to imagine whether there would be any discernible change if, without any change in the mutual situations of its constituents, the whole created world were either reflected about a plane so that east is changed to west, or (in response to Samuel Clarke’s counterargument) moved along a straight line with a certain velocity. Another of Newton’s thought experiment occurs in his De gravitatione, in which, imagining God to have endowed certain portions of extension with the properties of mobility and impenetrability (subject to the laws of collision), together with perceptibility, he asks whether we could distinguish these from the bodies apparent to the senses.
