thumb|200px|right|Illustration of mind–body dualism by [[René Descartes. Inputs are passed by the sensory organs to the pineal gland, and from there to the immaterial spirit.]]
In the philosophy of mind, mind–body dualism denotes either that mental phenomena are non-physical, or that the mind and body are distinct and separable. Thus, it encompasses a set of views about the relationship between mind and matter, as well as between subject and object, and is contrasted with other positions, such as physicalism and enactivism, in the mind–body problem. whereas there remains an immortal and perpetual intellective part of mind. For Plato, however, the soul was not dependent on the physical body; he believed in metempsychosis, the migration of the soul to a new physical body. It has been considered a form of reductionism by some philosophers, since it enables the tendency to ignore very big groups of variables by its assumed association with the mind or the body, and not for its real value when it comes to explaining or predicting a studied phenomenon.
Dualism is closely associated with the thought of René Descartes (1641), who holds that the mind is a nonphysical—and therefore, non-spatial—substance. Descartes clearly identified the mind with consciousness and self-awareness and distinguished this from the physical brain as the seat of intelligence. Hence, he was the first documented Western philosopher to formulate the mind–body problem in the form in which it exists today. However, the theory of substance dualism has many advocates in contemporary philosophy such as Richard Swinburne, William Hasker, J. P. Moreland, E. J. Lowe Charles Taliaferro, Seyyed Jaaber Mousavirad, and John Foster.
Dualism is contrasted with various kinds of monism. Substance dualism is contrasted with all forms of materialism, but property dualism may be considered a form of non-reductive physicalism.
Types
Ontological dualism makes dual commitments about the nature of existence as it relates to mind and matter, and can be divided into three different types:
- Substance dualism asserts that mind and matter are fundamentally distinct kinds of foundations. Notable defenders of substance dualism include John Foster, Stewart Goetz, Richard Swinburne and Charles Taliaferro.
Cartesian dualism, most famously defended by René Descartes, argues that there are two kinds of substances: mental and physical. Descartes states that the mental can exist outside of the body, and the body cannot think. Substance dualism is important historically for having given rise to much thought regarding the famous mind–body problem. It is compatible with theologies which claim that immortal souls occupy an independent realm of existence distinct from that of the physical world.
The Copernican Revolution and the scientific discoveries of the 17th century reinforced the belief that the scientific method was the unique way of knowledge. Bodies were seen as biological organisms to be studied in their constituent parts (materialism) by means of anatomy, physiology, biochemistry and physics (reductionism). Mind–body dualism remained the biomedical paradigm and model for the following three centuries. Emergent dualism asserts that mental substances come into existence when physical systems such as the brain reach a sufficient level of complexity.
Hasker has argued that emergent dualism is consistent with neuroscientific discoveries showing the dependence of mind on brain. He likens the individual mind to a magnetic field in its qualitative difference from the physical properties that generate it and also in its ability to act on the brain that generates it.
Thomistic dualism
Thomistic dualism is a type of dualism derived from the views of Thomas Aquinas. Edward Feser has written that: