Materialism

At its core, materialism is a form of monism—the belief that there is only one "kind" of thing in the universe. It asserts that matter is the fundamental substance of nature. In this view, everything we perceive as "mental"—thoughts, emotions, and self-awareness—is a byproduct of physical processes within the brain and nervous system. If the physical structure stops, the consciousness ceases to exist.

This stands in direct opposition to idealism, which claims that mind or spirit is the primary reality and that the material world is just a projection of consciousness. While materialists don't necessarily deny that we have experiences, they insist those experiences are "dependent realities." They are the music played by the instrument of the brain; without the wood and strings of the material, there is no song.

In the 17th century, "matter" was often thought of as tangible, inert "stuff"—like billiard balls hitting one another. However, as science evolved, it discovered entities that weren't "material" in the traditional sense, such as gravity, electromagnetic fields, and the spacetime continuum. To stay relevant, philosophers introduced "Physicalism" in the 1930s.

Physicalism is essentially Materialism 2.0. It argues that everything that exists is "physical," but it broadens the definition to include anything described by physics—including energy and exotic matter. Today, the terms are often used interchangeably, but "physicalism" is preferred by many because it doesn't limit reality to solid particles; it accommodates the invisible but measurable forces that govern the universe.

Materialism isn't a Western invention; it emerged independently across the globe during the "Axial Age" (c. 800–200 BC). In India, the Cārvāka school rejected the supernatural entirely, while in Greece, Leucippus and Democritus proposed that the world was composed of "atoms and void." These early thinkers sought to explain the world through mechanics rather than myths.

By the 19th century, Karl Marx transformed materialism from a theory about atoms into a theory about society. His "historical materialism" argued that the way humans produce their means of survival (economics) is the foundation of all social structures. For Marx, history isn't driven by new ideas or "great men," but by changes in the material conditions of life—the tools we use and the way we organize labor.

Reductionists believe that every complex phenomenon, like love or memory, can eventually be explained away by looking at neurons and chemicals. They see psychology as a "special science" that will eventually be translated into the language of physics. However, "non-reductive" materialists argue that some things, like the laws of geology or psychology, are "invisible" to basic physics—you can't explain a stock market crash using only the movement of subatomic particles.

More radical are the "Eliminative" materialists, such as Paul and Patricia Churchland. They argue that our current "folk psychology"—using words like "belief" or "desire"—is a failed scientific theory. Just as we stopped using the word "demons" to explain epilepsy once we understood neurology, eliminativists suggest we will eventually stop using the word "mind" once we fully map the brain's physical architecture.

The "material" in materialism has become increasingly difficult to define. In the 19th century, the rise of field physics showed that matter and energy are interchangeable. Modern quantum mechanics further complicated things; Werner Heisenberg famously noted that atoms are not "things" in the way we intuitively understand them. They are more like mathematical probabilities than solid objects.

Furthermore, the dominant cosmological model (Lambda-CDM) suggests that less than 5% of the universe is made of the "ordinary matter" we understand. The rest is dark matter and dark energy—substances we cannot see and do not fully understand. This creates a "Hempel's Dilemma" for materialists: if "matter" is constantly being redefined by new scientific discoveries, materialism has no fixed definition and simply becomes the belief that "whatever physics says is true."