Abstract

Questions concerning unity and development have centered almost exclusively on Plato's various conceptions of Forms. Little work has been done in the domain of his psychology, where similar questions assert themselves. In the Phaedo Plato employs a noncomposite conception of the soul in his primary argument for immortality, whereas in the Republic and the Phaedrus he argues for a tripartite psychology. These conceptions are often taken to be incompatible. There are two issues on which the seeming inconsistency turns: the mereology Plato accepts, and the metaphysical status of the soul in its various conceptions. I argue that the underlying metaphysics of the psychology changes in that Plato develops a view of the soul as governed by certain necessary principles, and whose status develops from the Phaedo to the Phaedrus according to its composition