A solid grasp of the main themes and arguments of the seventeenth-century philosopher Rene Descartes is essential for understanding modern thought, and a necessary entree to the work of the Empiricists and Immanuel Kant. It is also crucial to the study of contemporary epistemology, metaphysics, and philosophy of mind. This new edition of Georges Dicker's commentary on Descartes's masterpiece, Meditations on First Philosophy, features a new chapter on the Fourth Meditation and improved treatments of the famous cogito ergo sum and the notorious problem of the Cartesian Circle, among numerous oth