• Alexander of Aphrodisias
• determinism
• forms
• libertarianism
• moral responsibility
• origin of motion
• Stoics
• uncaused motion

This thesis is divided into two parts. The first part argues that Alexander of Aphrodisias held a libertarian view of moral responsibility. This view requires postulating the actual ability to act otherwise in the same circumstances, which is incompatible with universal causal determinism. While this claim has been made by several scholars, my aim is to systematically review all the relevant evidence. This should clarify some of the existing confusion among scholars regarding this subject; for example, whether Alexander considered agents to be undetermined by both external and internal causes and whether he believed dispositions to be fixed.
The beating heart of the thesis is its second part. Having established that Alexander did hold a libertarian view of moral responsibility, I focus on his response to a standard determinist objection to libertarianism: how can one avoid the absurdity of postulating uncaused motion if acting in more than one way in the same circumstances is indeed possible? Alexander replies that no uncaused motion is introduced because human actions are caused and initiated by the agents themselves; indeed, to be a rational human being is precisely to be the starting point of one’s own actions. This response to the determinist challenge has received little attention and has been dismissed as unsatisfactory. My aim is to show that Alexander’s strategy is not only well grounded in his (essentially Aristotelian) thought, but also worthy of philosophical consideration.