Aristotle on change and potentiality

The focus of this dissertation is Aristotle's definition of change in book three of his Physics. I argue that we can only understand Aristotle's definition against the background of skeptical doubts about the very possibility of change—and so also natural science—which exercised and influenced almost all of Aristotle's contemporaries and predecessors. These doubts are crystallized in the Parmenidean dilemma, which challenges the possibility of explaining change without contradiction. My analysis of Aristotle's treatment of the dilemma shows that he responds by introducing the formal tools necessary for an explanatory discourse of nature.;While this resolution frees us from logical difficulties in speaking about change, it does not yet identify the relevant explanatory principle: the “matter” out of which something comes to be. Aristotle's definition of change as the “entelecheia of a potential being, as such” specifies this entity as a “potential being.” I argue that the currently dominant interpretation of Aristotle s definition misconstrues both the dialectic with his predecessors and the grammar of the definition. Because of this, the interpretation obscures the fact that Aristotle is employing the key formal devices introduced in his treatment of Parmenides. I work out a novel interpretation of Aristotle's definition and its significance, on which change is defined as the activity of something incomplete. I show how this interpretation avoids many of the problems that have plagued others. I analyze his subsequent account of the relation between an agent's activity (such as building a house) and the corresponding suffering undergone by a patient (such as being built) and argue that the agent's activity is excluded from the scope of change. This illuminates Aristotle's elusive comparison between such activity and activities like seeing and contemplating that contain their ends.;In the final chapter, I consider whether Aristotle has the requisite notion of potential being, one that is not itself defined in terms of change, so that the longstanding charge of circularity against his definition of change might be avoided. To answer this question, I analyze the structure of Aristotle's Metaphysics Theta, his treatise on potentiality and actuality.