what is dualism in philosophy

Dualism is a philosophical concept that refers to the idea that there are two fundamental kinds or categories of things or principles. In the philosophy of mind, dualism is the theory that the mental and the physical, or mind and body, are in some sense, radically different kinds of things. Dualists in the philosophy of mind emphasize the radical difference between mind and matter, and they all deny that the mind is the same as the brain. There are various ways of dividing up kinds of dualism, including substance dualism, property dualism, and predicate dualism. Substance dualism requires that mind and body be composed of two ontologically distinct substances, while property dualism holds that mental properties are not reducible to physical properties. Predicate dualism is the weakest theory, in the sense that it claims least. Dualism is contrasted with monism, which is the theory that there is only one fundamental kind, category of thing, or principle.