Abstract

In this paper I interpret Newton’s speculative treatment of gravity as a relational, accidental property of matter that arises through what Newton calls “the shared action” of two bodies of matter. In doing so, I expand and extend on a hint by Howard Stein. However, in developing the details of my interpretation I end up disagreeing with Stein’s claim that for Newton a single body can generate a gravity/force field. I argue that when Newton drafted the first edition of the Principia in the mid 1680s, he thought that (at least a part of) the cause of gravity is the disposition inherent in any individual body, but that the force of gravity is the actualization of that disposition; a necessary condition for the actualization of the disposition is the actual obtaining of a relation between two bodies having the disposition. The cause of gravity is not essential to matter because God could have created matter without that disposition. Nevertheless, at least a part of the cause of gravity inheres in individual bodies and were there one body in the universe it would inhere in that body. On the other hand, the force of gravity is neither essential to matter nor inherent in matter, because (to repeat) it is the actualization of a shared disposition. A lone part-less particle would, thus, not generate a gravity field. Seeing this allows us to helpfully distinguish among a) accepting gravity as causally real; b) the cause(s) (e.g. the qualities of matter) of the properties of gravity; c) making claims about the mechanism or medium by which gravity is transmitted. This will help clarify what Newton could have meant when he insisted that gravity is a real force. I present my argument in opposition to Andrew Janiak’s influential and fine 2007 paper. Along the way, I call attention to my disagreement with Janiak on a number of secondary issues (e.g. Janiak’s attribution to Newton of a distinction between ‘local’ and ‘distant’ action; Janiak’s reading of the “Letter to Bentley,” etc).