The Self-Moving Soul in Plato, Aristotle, and the Neoplatonism of Proclus and Hermias

Self-motion is a key notion in Plato's philosophy. In multiple dialogues, Plato insists that the essential nature of the soul is to move itself. Self-motion not only makes the soul the first cause of all physical motion and life in the universe, but also provides it with the necessary ontological structure to be truly free in the choices that it makes. However, a closer look at the idea of a self-moving soul shows how this concept is full of difficulties. The first philosopher providing an elaborate criticism of the self-moving soul was Plato’s famous student Aristotle. Contrary to his teacher, Aristotle believed that the concept of motion could not be properly used for immaterial entities such as the soul, but was only applicable to the physical realm. Thus, ancient Platonists, who recognized the importance of the doctrine for Platonic philosophy and adopted Plato’s theory of the self-moving soul, had to deal with Aristotle’s substantial criticism of it. My dissertation offers a narrative of the concept of the self-moving soul, which is both historical and theoretical. This narrative starts at the origin of the concept in Plato’s dialogues, develops through its critical reception in Aristotle’s writings, and culminates in the Neoplatonic defense and redefinition of the concept of the self-moving soul as it is presented in the works of Hermias and Proclus. The central aim of this work is to establish the centrality of the concept of the self-moving soul, including its broader philosophical implications, in Plato’s philosophy and in the Neoplatonism of Hermias and Proclus. In particular, it assesses how the Platonic doctrine of the self-moving soul was developed in the Neoplatonic thought of Hermias and Proclus through their critical engagement with Aristotle’s criticism and insights.