Why the Parts of Absolute Space are Immobile

Newton’s arguments for the immobility of the parts of absolute space have been used to licence several proposals concerning his metaphysics. This paper clarifies Newton. Notably, it demonstrates, contrary to Nerlich (2005), that Newton does not appeal to the identity of indiscernibles, but rather to a view about de re representation. Additionally, I show, contrary to DiSalle (1994), that the argument does not reveal Newton to be an anti-substantivalist. Its premises entail that ‘Leibniz shifts’ in space are impossible, but they also entail that all motion is the relative motion of bodies; hence they cannot be core doctrines. Since Newton took absolute motion to be motion with respect to absolute space, it is not surprising that he held the parts of absolute space to be at mutual rest – otherwise, with respect to what part is absolute motion to be taken? In fact, Newton held the stronger view that the parts were necessarily motionless, and in two well-known passages argued for this claim: first in the unpublished essay De Gravitatione, and again in the Scholium to the Definitions in his Principia. The arguments have been rather widely discussed, to various ends, but, I will argue, they have been misunderstood in a number of ways. More specifically, in §1 I will argue (against Nerlich, 2005, for instance) that De Gravitatione contains two arguments for immobility, while the Scholium contains only one of them. In particular, the ‘identity argument’ that is the focus of recent discussion (and this paper) is only found in De Gravitatione. This point is not made merely to correct a mistake in the literature, but to show that the premises of Newton’s argument do not appear in his more considered, published works, and thus do not have the same status as his core views. §2 will canvas some possible interpretations of the identity argument and their problems, and explicate the most charitable, natural reading – according to which the premises are consistent with absolute space as conceived by Newton. One reason that the argument has attracted attention (e.g., DiSalle 1994) is that it also seems to show that Newton denied a ‘substantival’ view of space: its premises imply rather immediately that worlds that (putatively) differ only in the absolute location of the material universe do not in