Berkeley's Criticism of the Newtonian Account of Rotation

Monica Solomon

University of Notre-Dame

Earman (1989, pp. 73-5) mentions Berkeley's response to the Newtonian treatment of rotation derived from Berkeley's Principles (1710) and De Motu (1721). Earman starts by mentioning that Berkeley's views did not get serious consideration and he cites Leibniz's three-line dismissal. Although in his criticism Berkeley is thought to have been a precursor of Einstein and Mach(Popper 1953), Earman argues that “Berkeley's critique of the bucket experiment was every bit as effective as his use of tar water to treat the bloody flux in Ireland” (Ibid., p. 73). In this paper, I take a closer look at Berkeley's criticism and argue that Earman's conclusion is unjustified. Although Berkeley did not attempt to provide an alternative relational account of motion, his criticism against the Newtonian absolute space (when connected with the parts of De Motu in which he criticizes the notions of force, impulse, etc.) is more substantial and invites a re-reading of Newtonian examples of rotation in the Scholium to the definitions (the bucket experiment and the two rotating globes). In particular, I argue that Berkeley's critique is more successful when directed at the Newtonian notion of “absolute motion” rather than at the question whether absolute space is denotationless. Berkeley challenges the Newtonian treatment of rotation with the conclusion that “in now way follows that absolute circular motion is necessarily recognized by the forces of retirement from the axis of motion”. Newton needs to answer two questions: (1) how do we recognize the effect of the changes in the forces of receding from axis? And (2) why is absolute space needed for this account? In my paper, I show that answering these two questions brings forward a necessary distinction between absolute and true motion (although my distinction is different from Huggett's (2012)), and that Berkeley's criticism is more extensive and more insightful than Earman presented it. My paper is organized as follows: I introduce briefly Newton's examples in the Scholium and their purported roles as represented by major threads of interpretation in the scholarship. In the second section, I look at how Berkeley interpretation of the bucket experiment brings novel challenges and I assess his criticism. My aim, however, is not to decide whether Berkeley interpreted Newton correctly, but rather to point out that Berkeley's criticism is justified by the larger metaphysical framework of De Motu. Moreover, reading Newton through his lenses also brings to light interesting features of Newtonian mathematical concepts. One take-home message is that the disagreement between Berkeley and Newton with respect to the treatment of rotation is best seen not as a conflict between relational and absolute theories of space, but rather as a clash between two different philosophies of mathematics. Secondly, I suggest that Huygens raised a similar objection regarding the two globes experiment, and that the Newtonian response that I constructed here (i.e. true motion is the type of motion that is only changed by impressed forces) is a promising venue for replying to Huygens as well.