Plato and his Predecessors considers how Plato represents his philosophical predecessors in a late quartet of dialogues: the Theaetetus, the Sophist, the Politicus and the Philebus. These predecessors appear in imaginary conversations; and they are refuted when they fail to defend their philosophical positions in debate. Professor McCabe argues that Plato's reflections on these conversations allow him to develop a new account of the principles of reason, and forge a fresh view of the best life--the life of the philosopher.