Abstract

This essay explores various problematical aspects of Descartes’ conservation principle for the quantity of motion (size 3 speed), particularly its largely neglected “dual role” as a measure of both durational motion and instantaneous “tendencies towards motion.” Overall, an underlying non‐local, or “holistic,” element of quantity of motion (largely derived from his statics) will be revealed as central to a full understanding of the conservation principle’s conceptual development and intended operation; and this insight can be of use in responding to some of the recent and traditional criticisms of Descartes’ physics.