This thesis analyses the method, purpose, and results of Aristotle's treatment of a select number of Presocratic and Platonic theses about the soul within the context of De Anima 1. Contrary to a prevalent interpretation of De Anima 1 which sees Aristotle's treatment of his predecessors' psychological views as dialectical, I argue that Aristotle treats his predecessors as having offered potentially viable hypotheses about the nature of the soul, and that these hypotheses ...