Aristotle’s most fundamental distinction between changes and other activities is not that ofMetaphysicsΘ.6, between end-exclusive and end-inclusive activities, but one implicit inPhysics3.1’s definition of change, between the activity of something incomplete and the activity of something complete. Notably, only the latter distinction can account for Aristotle’s view, inPhysics3.3, that ‘agency’—effecting change in something, e.g. teaching—does not qualify strictly as a change. This distinction informsDe Anima2.5 and imparts unity to Aristotle’s extended treatment of change inPhysics3.1-3.

When I raise my arm, what makes it the case that my arm's going up is an instance of my raising my arm? In this paper, I discuss Aristotle's answer to this question. His view, I argue, is that my arm's going up counts as my raising my arm just in case it is an exercise of a certain kind of causal power of mine. I show that this view differs in an interesting way both from the Davidsonian ‘standard causal (...) account’ of action and from accounts put forward by recent critics of Davidson, such as Hornsby, Alvarez and Hyman. (shrink)