Materialism

In philosophy, materialism is that form of physicalism which holds that the only thing that can truly be said to exist is matter; that fundamentally, all things are composed of material and all phenomena are the result of material interactions. Science uses a working assumption, sometimes known as methodological naturalism, that observable events in nature are explained only by natural causes without assuming the existence or non-existence of the supernatural. As a theory, materialism belongs to the class of monist ontology. As such, it is different from ontological theories based on dualism or pluralism. In terms of singular explanations of the phenomenal reality, materialism stands in sharp contrast to idealism.

Overview
The first detailed description of the philosophy occurs in the scientific poem De Rerum Natura by Lucretius in his recounting of the mechanistic philosophy of Democritus and Epicurus. According to this view, all that exists is matter and void, and all phenomena are the result of different motions and conglomerations of base material particles called "atoms." De Rerum Natura provides remarkably insightful, mechanistic explanations for phenomena, like erosion, evaporation, wind, and sound, that would not become accepted for more than 1500 years. Famous principles like "nothing can come from nothing" and "nothing can touch body but body" first appeared in this most famous work of Lucretius.

The view is perhaps best understood in its opposition to the doctrines of immaterial substance applied to the mind historically, and most famously by René Descartes. However, by itself materialism says nothing about how material substance should be characterized. In practice it is frequently assimilated to one variety of physicalism or another.

Materialism is sometimes allied with the methodological principle of reductionism, according to which the objects or phenomena individuated at one level of description, if they are genuine, must be explicable in terms of the objects or phenomena at some other level of description -- typically, a more general level than the reduced one. Non-reductive materialism explicitly rejects this notion, however, taking the material constitution of all particulars to be consistent with the existence of real objects, properties, or phenomena not explicable in the terms canonically used for the basic material constituents. Jerry Fodor influentially argues this view, according to which empirical laws and explanations in "special sciences" like psychology or geology are invisible from the perspective of, say, basic physics. A vigorous literature has grown up around the relation between these views.

Materialism typically contrasts with dualism, phenomenalism, idealism, and vitalism. The definition of "matter" in modern philosophical materialism extends to all scientifically observable entities such as energy, forces, and the curvature of space. In this sense, one might speak of the "material world".

Materialism has frequently been understood to designate an entire scientific, rationalistic world view, particularly by religious thinkers opposed to it, who regard it as a spiritually empty religion. Marxism also uses materialism to refer to the scientific world view, It emphasizes a "materialist conception of history", which is not concerned with metaphysics but centers on the empirical world of actual human activity (practice, including labor) and the institutions created, reproduced, or destroyed by that activity (see materialist conception of history).

Varieties of materialism

 * Christian materialism
 * Dialectical materialism (See also Marxist philosophy of nature.)
 * Historical materialism (Marxist application of materialism to history)
 * Eliminative materialism
 * Emergent materialism
 * Evolutionary materialism
 * French materialism
 * Reductive materialism / Reductionism
 * Cartesian materialism

History of materialism
Ancient Greek philosophers like Thales, Parmenides, Anaxagoras, Democritus, Epicurus, and even Aristotle prefigure later materialists. Later on, Thomas Hobbes and Pierre Gassendi represent the materialist tradition, in opposition to René Descartes' attempts to provide the natural sciences with dualist foundations. Later materialists included Denis Diderot and other French enlightenment thinkers, as well as Ludwig Feuerbach.

Schopenhauer wrote that "...materialism is the philosophy of the subject who forgets to take account of himself." (The World as Will and Representation, II, Ch. 1) "Everything objective, extended, active, and hence everything material, is regarded by materialism as so solid a basis for its explanations that a reduction to this (especially if it should ultimately result in thrust and counter-thrust) can leave nothing to be desired. (But) [a]ll this is something that is given only very indirectly and conditionally, and is therefore only relatively present, for it has passed through the machinery and fabrication of the brain, and hence has entered the forms of time, space, and causality, by virtue of which it is first of all presented as extended in space and operating in time." (ibid., I, §7)

Karl Marx and Friedrich Engels, turning the idealist dialectics of Georg Hegel upside down, provided materialism with a view on processes of quantitative and qualitative change called dialectical materialism, and with a materialist account of the course of history, known as historical materialism.

In recent years, Paul and Patricia Churchland have advocated eliminativist materialism, which holds that mental phenomena simply do not exist at all -- that talk of the mental reflects a totally spurious "folk psychology" that simply has no basis in fact, something like the way that folk science speaks of demon-caused illness.