Abstract
This paper recovers a historically important debate about the ontological status of an agent’s action. When one physical substance acts upon another what is the ontological status of the causal activity by which the former moves the latter? According to the Aristotelian position on action defended up through the seventeenth century, agents cause their effects immediately. There is no intervening causative entity by which an agent causes a change in its patient. The agent’s action is the very motion or change which the agent causes. This paper examines Thomas Aquinas’s intriguing development of the Aristotelian position and Peter Auriol’s incisive critique. Auriol contends that a physical agent’s action must be really distinct from, causally prior to, and separable from the motion which the agent causes. Auriol posits that actions are dynamic, fleeting causative entities which exist just as long as an agent is initiating a motion. The recovery of Auriol’s position challenges a standard historical narrative which holds that up through the early modern period philosophers thought that causes must be persistent stable objects. Auriol’s views show that transitory causative entities, such as forces and events, popularized in the mid- eighteenth century, have a legacy in medieval thought. Furthermore, Auriol’s position that action is a really distinct and separable entity from motion anticipates an important shift in historical thinking about the nature of motion and its ability to persist without an active cause.