Materialism

Materialism is a form of philosophical monism in metaphysics, according to which matter is the fundamental substance in nature, and all things, including mental states and consciousness, are results of material interactions. According to philosophical materialism, mind and consciousness are caused by physical processes, such as the neurochemistry of the human brain and nervous system, without which they cannot exist. Materialism directly contrasts with monistic idealism, according to which consciousness is the fundamental substance of nature.

Materialism is closely related to physicalism—the view that all that exists is ultimately physical. Philosophical physicalism has evolved from materialism with the theories of the physical sciences to incorporate forms of physicality in addition to ordinary matter (e.g. spacetime, physical energies and forces, and exotic matter). Thus, some prefer the term physicalism to materialism, while others use them as synonyms. Materialism is also related to naturalism—the position that only natural laws and forces operate in the universe.

Discoveries of neural correlates between consciousness and the brain are taken as empirical support for materialism, but some philosophers of mind find that association fallacious or consider it compatible with non-materialist ideas. Alternative philosophies opposed or alternative to materialism or physicalism include idealism, pluralism, dualism, panpsychism, and other forms of monism.

Epicureanism is a philosophy of materialism from classical antiquity that was a major forerunner of modern science. Classical atomism predates Epicurus: fifth‑century BCE thinkers Leucippus and Democritus explained all change as the collisions of indivisible atoms moving in the void. Epicureanism refined this materialist picture. Epicurus held that everything—including mind—consists solely of atoms moving in the void; to explain how parallel falling atoms could ever meet, he postulated the clinamen, an extremely slight lateral deviation that initiates collisions without invoking supernatural causes and that need not imply genuine indeterminism.

In late modern philosophy, German atheist anthropologist Ludwig Feuerbach signaled a new turn in materialism in his 1841 book The Essence of Christianity, which presented a humanist account of religion as the outward projection of man's inward nature. Feuerbach introduced anthropological materialism, a version of materialism that views materialist anthropology as the universal science.

Feuerbach's variety of materialism heavily influenced Karl Marx, who in the late 19th century elaborated the concept of historical materialism—the basis for what Marx and Friedrich Engels outlined as scientific socialism.

Materialism belongs to the class of monist ontology, and is thus different from ontological theories based on dualism or pluralism. For singular explanations of the phenomenal reality, materialism is in contrast to idealism, neutral monism, and spiritualism. It can also contrast with phenomenalism, vitalism, and dual-aspect monism. Its materiality can, in some ways, be linked to the concept of determinism, as espoused by Enlightenment thinkers.

Despite the multiplicity of named schools, philosophy ultimately confronts a single binary: materialism versus idealism. Uncompromising materialism—today often called physicalism—holds that the universe is nothing but matter‑energy in motion; every phenomenon, from stellar fusion to human thought, is exhaustively explicable as organised interactions of physical entities. Matter is self‑moving and self‑organising, so it is scientifically superfluous to posit immaterial substances or disembodied minds. On this view, consciousness is a higher‑order property of certain complex material systems, not an ontological primitive. Idealism, by contrast, reverses the causal arrow: it elevates mind, spirit or abstract Forms to constitutive reality and demotes the material world to a mere appearance—a position that historically provided philosophical cover for religion and other supernatural doctrines.