Introduction | Dualism | Monism
Philosophy of Mind is the branch of philosophy that studies the nature of the mind (mental events, mental functions, mental properties and consciousness) and its relationship to the physical body. It intersects to some extent with the fields of neurobiology, computer science and psychology.
Within philosophy, the Philosophy of Mind is usually considered a part of Metaphysics, and has been particularly studied by schools of thought such as Analytic Philosophy, Phenomenology and Existentialism, although it has been discussed by philosophers from the earliest times. It has a potential influence on philosophical questions such as the nature of death, the nature of free will, the nature of what a person is (and his or her identity and the self), and the nature of emotion, perception and memory.
The central issue in Philosophy of Mind is the mind-body problem (the relationship of the mind to the body), and the challenge is to explain how a supposedly non-material mind can influence a material body and vice-versa. The two major schools of thought that attempt to resolve this problem are Dualism and Monism (see the sections below), with Pluralism as a small minority viewpoint.
However, there are those (notably Ludwig Wittgenstein and his followers) who reject the problem as an illusory one which has arisen purely because mental and biological vocabulary are incompatible, and such illusory problems arise if one tries to describe the one in terms of the other's vocabulary, or if the mental vocabulary is used in the wrong contexts.
Dualism is the position that mind and body are in some categorical way separate from each other, and that mental phenomena are, in some respects, non-physical in nature. It can be traced back to Plato, Aristotle, and the Sankhya and Yoga schools of Hindu philosophy, but it was most precisely formulated by René Descartes in the 17th Century. Descartes was the first to clearly identify the mind with consciousness and self-awareness, and to distinguish this from the brain, which was the physical seat of intelligence.
Dualism appeals to the common-sense intuition of the vast majority of non-philosophically-trained people, and the mental and the physical do seem to most people to have quite different, and perhaps irreconcilable, properties. Mental events have a certain subjective quality to them (known as qualia or "the ways things seem to us"), whereas physical events do not.
There are three main Dualist schools of thought:
- Substance Dualism (or Cartesian Dualism) argues that the mind is an independently existing substance - the mental does not have extension in space, and the material cannot think. This is the type of Dualism most famously defended by Descartes, and it is compatible with most theologies which claim that immortal souls occupy an independent "realm" of existence distinct from that of the physical world.
- Property Dualism maintains that the mind is a group of independent properties that emerge from the brain, but that it is not a distinct substance. Thus, when matter is organized in the appropriate way (i.e. in the way that living human bodies are organized), mental properties emerge.
There are three main types of Property Dualism:
- Interactionism, which allows that mental causes (such as beliefs and desires) can produce material effects, and vice-versa. Descartes believed that this interaction physically occurred in the pineal gland.
- Occasionalism, asserts that a material basis of interaction between the material and immaterial is impossible, and that the interactions were really caused by the intervention of God on each individual occasion. Nicholas Malebranche was the major proponent of this view.
- Parallelism (or Psychophysical Parallelism), holds that mental causes only have mental effects, and physical causes only have physical effects, but that God has created a pre-established harmony so that it seems as if physical and mental events (which are really monads, completely independent of each other) cause, and are caused by, one another. This unusual view was most prominently advocated by Gottfried Leibniz.
- Epiphenomenalism, which asserts that mental events are causally inert (i.e. have no physical consequences). Physical events can cause other physical events, and physical events can cause mental events, but mental events cannot cause anything, since they are just causally inert by-products of physical events which occur in the brain (i.e. epiphenomena) of the physical world. This doctrine was first formulated by Thomas Henry Huxley in the 19th Century, although based on Thomas Hobbes' much earlier Materialism theories.
- Predicate Dualism argues that more than one predicate (how we describe the subject of a proposition) is required to make sense of the world, and that the psychological experiences we go through cannot be redescribed in terms of (or reduced to) physical predicates of natural languages.
Monism is the position that mind and body are not ontologically distinct kinds of entities. This view was first advocated in Western Philosophy by Parmenides in the 5th Century B.C., and variations on it were and was later espoused by Baruch Spinoza in the 17th Century and George Berkeley in the 18th Century.
There are three main Monist schools of thought:
- Physicalism (also known as Materialistic Monism) argues that the mind is a purely physical construct (the only existing substance is physical), and will eventually be explained entirely by physical theory, as it continues to evolve. With the huge strides in science (especially in atomic theory, evolution, neuroscience and computer technology) in the 20th Century, Physicalism of various types has become the dominant doctrine.
There are two main types:
- Reductive Physicalism, which asserts that all mental states and properties will eventually be explained by scientific accounts of physiological processes and states, has been the most popular form during the 20th Century. There are three main types:
- Behaviourism, which holds that mental states are just descriptions of observable behaviour.
- Type Identity Theory, which holds that specific mental states are identical to specific physical internal states of the brain.
- Functionalism, which holds that mental states (beliefs, desires, being in pain, etc.) are constituted solely by their functional role and can be characterized in terms of non-mental functional properties.
- Non-Reductive Physicalism, which argues that, although the brain is all there is to the mind, the predicates and vocabulary used in mental descriptions and explanations cannot be reduced to the language and lower-level explanations of physical science. Thus, mental states supervene (depend) on physical states, and there can be no change in the mental without some change in the physical, but they are not reducible to them.
There are three main types:
- Anomalous Monism, which states that mental events are identical with physical events, but that the mental is anomalous i.e. these mental events are not regulated by strict physical laws.
- Emergentism, which involves a layered view of nature, with the layers arranged in terms of increasing complexity, each corresponding to its own special science.
- Eliminativism (or Eliminative Materialism), which holds that people's common-sense understanding of the mind ("folk psychology") is hopelessley flawed, and will eventually be replaced (eliminated) by an alternative, usually taken to be neuroscience.
- Idealism (or Mentalism or Immaterialism) maintains that the mind is all that exists (the only existing substance is mental), and that the external world is either mental itself, or an illusion created by the mind. According to Idealism, then, the problem of the interaction between mind and body is not a problem at all. A pure form of Idealism was espoused by Bishop George Berkeley, and variations were formulated by various members of the German Idealism school, including Kant, Fichte, Schelling and Hegel.
- Neutral Monism maintains that existence consists of one kind of primal substance (hence monism), which in itself is neither mental nor physical, but is capable of mental and physical aspects or attributes (it is sometimes described as a dual-aspect theory). Thus, there is some other, neutral substance (variously labelled as Substance, Nature or God), and that both matter and mind are properties of this other unknown substance. Such a position was adopted by Baruch Spinoza and also by Bertrand Russell for a time.