At It Again: Time-Travel and the At–At Account of Motion

Abstract

According to Russell’s At–At Account of Motion, necessarily, something moves if and only if it’s at one place at one time, and at a distinct place at a distinct time. This, many believe, is all that motion consists in. However, if it is possible for an entity to be at more than one place at more than one time (that is, to persist while multiply located), the At–At Account will entail that the entity is in motion even if, intuitively, the entity is simply at rest in two places at once. I will argue that these cases, if possible, give us reason to reject the At–At Account, and that if we endorse the At–At Account as an analysis, even the analytic possibility of the cases will be problematic. Further, we have reason to reject the stronger claim of Motion Supervenience, on which the facts about the motion of an individual within an interval are wholly determined by facts about the object’s location within that interval together with identity facts about regions and times.