This book examines psycho-physical dualism as developed by the Nyāya school of Indian philosophy. Dualism is important to many world religions which promote personal immortality and to morality which promotes free will. For the Nyāya, the self is a permanent, immaterial substance to which non-physical internal states like cognition belong. This view is challenged by other Indian schools, especially the Buddhist and Cārvāka schools. Chakrabarti brings out the connections between the Indian and the Western debates over the mind-body problem and shows that the Nyāya position is well developed, well articulated, and defensible. He shows that Nyāya dualism differs from Cartesian dualism and is not vulnerable to some traditional objections against the latter. A brief discussion of the Sāṃkhya and the Advaita theories of the self and the critique of these views from the Nyāya standpoint are included, as well as a discussion of a classical Nyāya causal argument for the existence of God. The appendix contains an annotated translation of selected portions of Udayana's masterpiece, Ātmatattvaviveka (Discerning the Nature of the Self.)