Dualism

Dualism, any religious or philosophical system characterized by a fundamental opposition of two independent or complementary principles. Among religious dualisms are the unending conflict of good and evil spirits envisaged in Zoroastrianism and the opposition of light and darkness in Gnosticism and Manichaeism. The Chinese complementary principles of yin and yang exemplify a cosmological dualism, while the mind-body dualism of René Descartes is the best-known philosophical type. Dualism is often opposed to monism and pluralism.