In philosophy and metaphysics, materialism is a type of monism that believes matter is the basic substance of the universe. This means that everything, such as the mind and consciousness, comes from physical interactions and depends on processes in the body, like those in the brain and nervous system. Materialism is different from monistic idealism, which believes consciousness is the most important part of reality. It is also connected to naturalism, the idea that only natural laws and forces exist in the universe, and to physicalism, the belief that everything that exists is ultimately physical. Physicalism builds on materialism by including things like space and time, energy, forces, and unusual matter, and some people use these terms interchangeably. Other views that differ from materialism or physicalism include idealism, pluralism, dualism, solipsism, panpsychism, and other forms of monism.

Overview

Materialism is a philosophy that believes matter is the most important part of the world, and that thoughts or consciousness come from matter or may not exist at all. In its strongest form, materialism says the real world includes only physical things, but it also includes space and time if they are real, not just ways of describing relationships. Materialism is part of a group of ideas called monist ontology, which means it believes only one type of reality exists. This makes it different from ideas that say two or more types of reality exist, like dualism or pluralism. Materialism also contrasts with other ideas like idealism, neutral monism, and spiritualism. It can also be different from theories like phenomenalism, vitalism, and dual-aspect monism. Materialism is sometimes connected to determinism, a belief that everything happens in a predictable way, as some thinkers during the Enlightenment argued.

In modern philosophy, the words "materialism" and "physicalism" are often used the same way, but they have different histories. "Materialism" was used in English in the late 1600s, while "physicalism" was introduced in the 1930s by philosophers Otto Neurath and Rudolf Carnap. They argued that all statements could be translated into language about physical things. Some people prefer "physicalism" because physics has discovered things like gravity, which are physical but not clearly "material" in the old sense. Today, some materialists include other scientific ideas, like energy, forces, and space and time, in their definition. However, some philosophers, like Mary Midgley, say the word "matter" is hard to define clearly.

Materialism is often linked to reductionism, which is the idea that complex things can be explained by simpler parts. For example, if something happens at one level of description, it must be explained by something at a simpler level. Non-reductive materialism disagrees with this. It says that even though everything is made of physical parts, some real things, like objects or properties, cannot be fully explained by basic physical parts. A philosopher named Jerry Fodor believed this, arguing that fields like psychology or geology use rules and explanations that basic physics cannot see.

History

Materialism developed, possibly independently, in several geographically separated regions of Eurasia during what Karl Jaspers called the Axial Age (c. 800–200 BC).

In ancient Indian philosophy, materialism began around 600 BC with the works of Ajita Kesakambali, Payasi, Kanada, and followers of the Cārvāka school. Kanada was one of the early supporters of atomism. The Nyaya–Vaisesika school (c. 600–100 BC) developed one of the earliest forms of atomism. However, their belief in God and their view that consciousness was not material made them not fully materialists. Buddhist and Jaina traditions continued the atomic ideas.

In ancient Greece, thinkers like Leucippus, Democritus, and Epicurus laid the groundwork for later materialist ideas. The Latin poem De Rerum Natura by Lucretius (99–c. 55 BC) reflected the views of Democritus and Epicurus. According to this view, everything is made of matter and void, and all events result from the movement and grouping of basic particles called atoms ("indivisibles"). De Rerum Natura explained natural processes like erosion, evaporation, wind, and sound. A famous idea, "nothing can touch body but body," first appeared in Lucretius’s work. Democritus and Epicurus did not believe that matter and space were the same, but rather that space was a separate kind of being.

Epicureanism was a materialist philosophy from ancient times that helped shape modern science. Earlier thinkers like Leucippus and Democritus (5th century BCE) explained all changes as collisions of indivisible atoms moving through empty space. Epicurus improved this idea, claiming that even the mind was made of atoms moving in the void. To explain how atoms could meet, he proposed the clinamen, a tiny sideways movement that caused collisions without needing supernatural causes.

Wang Chong (27–c. 100 AD) was a Chinese thinker in the early Common Era who supported materialism. Later, the Indian materialist Jayaraashi Bhatta (6th century) wrote Tattvopaplavasimha (The Upsetting of All Principles), which challenged the Nyāya Sūtra’s ideas about knowledge. The Cārvāka philosophy, which was materialist, seemed to disappear after 1400. When Madhavacharya wrote Sarva-darśana-samgraha (A Digest of All Philosophies) in the 14th century, he had no Cārvāka texts to reference.

In 12th-century al-Andalus, the Arab philosopher Ibn Tufail (also known as Abubacer) discussed materialism in his book Hayy ibn Yaqdhan (Philosophus Autodidactus), which hinted at later ideas about historical materialism.

In France, Pierre Gassendi (1592–1665) supported materialism, opposing René Descartes’s dualist views. Later, the materialist and atheist Jean Meslier (1664–1729) and French thinkers like Julien Offray de La Mettrie, Denis Diderot, Étienne Bonnot de Condillac, and Claude Adrien Helvétius promoted materialist ideas. The German-French Baron d'Holbach and other Enlightenment thinkers also supported materialism.

In England, materialism was explored by Francis Bacon, Thomas Hobbes, and John Locke. Scottish philosopher David Hume became one of the most important materialist thinkers in the 18th century. John "Walking" Stewart believed that matter had a moral aspect, which influenced William Wordsworth’s poetry.

In late modern philosophy, Ludwig Feuerbach’s 1841 book The Essence of Christianity introduced anthropological materialism, a view that religion reflects human nature. Feuerbach’s ideas influenced Karl Marx, who later developed historical materialism, the foundation of scientific socialism as described by Friedrich Engels in Socialism: Scientific and Utopian (1880).

Engels later wrote Dialectics of Nature (1883), which developed a "materialist dialectic" philosophy. This idea, called dialectical materialism, was further expanded by Vladimir Lenin in Materialism and Empirio-criticism (1909), linking materialism to political views.

In the mid-19th century, German materialism included thinkers like Ludwig Büchner, Jacob Moleschott, and Carl Vogt, though they disagreed on topics like evolution and life’s origins.

According to Marxist theorist George Novack, philosophy ultimately faces a choice between materialism and idealism.

Today, analytic philosophers like Daniel Dennett, Willard Van Orman Quine, Donald Davidson, and Jerry Fodor work within a scientific materialist framework, offering different ways to explain the mind, such as functionalism, anomalous monism, and identity theory.

Scientific materialism is often described as reductive materialism, which reduces all theories to facts. In the early 21st century, Paul and Patricia Churchland supported eliminative materialism, arguing that some mental concepts, like "belief," are not real and are based on false ideas.

Between reductive materialism (which reduces theories to facts) and eliminative materialism (which removes some theories), revisionary materialism is a middle ground.

Christian List argues that first-person perspectives, such as the experience of being oneself, challenge physicalism. He claims that since first-person facts cannot depend on physical facts, this refutes physicalism and many forms of dualism.

Contemporary philosopher Gilles Deleuze worked to improve classical materialist ideas. Thinkers like Manuel DeLanda, who use this approach, are called "new materialists." New materialism has become a separate field, with courses, books, and conferences dedicated to it. Jane Bennett’s 2010 book Vibrant Matter helped bring ideas about monist ontology and vitalism back into academic discussions.

Defining "matter"

Scientists and philosophers have long discussed what matter is and how it exists. Some key questions include:

• Is there one basic type of matter that everything is made of, or are there many different types?
• Is matter a continuous substance that can take many forms, or is it made of separate, unchanging parts?
• Does matter have its own natural properties, or does it lack them?

In the 1800s, new ideas in physics, such as field theory, challenged the old view of matter as a solid "stuff." According to relativity, matter and energy (including energy spread across space, like in fields) can change into each other. This suggests that energy might be the most basic form of matter, with matter being one way energy appears. In contrast, the Standard Model of particle physics uses quantum field theory to explain how particles and forces interact. This model suggests that fields might be the most basic form, and energy is a feature of these fields.

The main model scientists use to describe the universe, called the Lambda-CDM model, shows that less than 5% of the universe's energy is the kind of matter described by the Standard Model. Most of the universe is made of dark matter and dark energy, but scientists do not yet fully understand what these are made of.

When quantum physics developed, some scientists thought the idea of matter had changed, while others believed the old view could no longer be correct. Werner Heisenberg said, "The idea that the world around us can be understood the same way at the level of atoms is wrong. Atoms are not simple objects."

The concept of matter has changed over time as new scientific discoveries were made. This means that materialism, the idea that everything is made of matter, depends on the specific theory of matter being used. Noam Chomsky noted that any property could be considered material if matter is defined to include that property.

Philosopher Gustavo Bueno uses the term "stroma" instead of "matter" to describe a more precise idea.

Physicalism

George Stack explains the difference between materialism and physicalism:

Not all ideas about physicalism are connected to theories about how meaning is determined or how we directly experience the world. Instead, physicalists believe that the mathematical models used to describe the world include all elements of reality. Materialist physicalists also believe these models describe areas without feelings or thoughts. This means the basic nature of the physical world is not related to experiences or feelings.

Criticism and alternatives

Rudolf Peierls, a scientist who worked on the Manhattan Project, disagreed with the idea that everything can be explained by physical laws. He stated, "The idea that physics can fully explain human abilities, such as knowledge and consciousness, is not correct. Something important is still missing."

Erwin Schrödinger, another scientist, said, "Consciousness cannot be explained using only physical explanations. Consciousness is basic and cannot be described in any other way."

Werner Heisenberg believed that discoveries in quantum physics challenged the idea that everything is made of physical matter. He explained that quantum particles exist as probabilities rather than definite objects. This supports the idea that physical reality might be better understood through mathematical concepts, similar to ideas proposed by the ancient philosopher Plato, rather than through materialist views. He noted, "Modern physics opposes the materialist ideas of the ancient Greek philosopher Democritus and supports the views of Plato and the Pythagoreans."

Some scientists from the 20th century, such as Eugene Wigner and Henry Stapp, and others today, including Stephen Barr, Paul Davies, and John Gribbin, argued that materialism has problems because of recent discoveries in physics, like quantum mechanics and chaos theory. In their book The Matter Myth, Paul Davies and John Gribbin wrote:

— Paul Davies and John Gribbin, The Matter Myth, Chapter 1: "The Death of Materialism"

People who support digital physics, which suggests that information, not matter, is the most basic part of reality, also share these concerns. John Archibald Wheeler, a scientist who supported digital physics, said, "All physical things and matter come from information. This is a universe where observers play a role." Some early scientists who studied quantum theory, like Max Planck, also agreed. He wrote:

— Max Planck, Das Wesen der Materie (1944)

James Jeans, another scientist, said, "The universe seems more like a great thought than a great machine. The mind is not a random addition to the physical world."

In The Critique of Pure Reason, the philosopher Immanuel Kant argued against materialism while defending his own ideas about reality. He believed that change and time require something lasting to exist.

Some modern thinkers, like those in postmodern and poststructuralist schools, question whether any single theory can fully explain reality. Mary Midgley, a philosopher, said that materialism, especially the idea that everything can be reduced to physical matter, is self-contradictory.

Philosophers like Hegel and Berkeley argued against materialism by supporting idealism, which suggests that the mind is more fundamental than matter. Berkeley, for example, said that matter cannot be directly experienced, and that all we know is perception. He argued that matter’s existence must be inferred from the stability of our perceptions, not from direct experience.

If physical matter and energy are seen as necessary to explain the physical world but cannot explain the mind, this leads to dualism. Other ideas, such as emergence, holism, and process philosophy, aim to improve on traditional materialism without fully rejecting it.

Some critics argue that materialism is used in a way that is too narrow or overly confident in its ability to explain everything. John Polkinghorne, a scientist and theologian, criticized "promissory materialism," which is the belief that materialism will eventually explain everything, even if it hasn’t yet. He prefers a view called "dual-aspect monism," which suggests that mind and matter are two sides of the same reality.

Some scientists have been criticized for not clearly defining what they mean by "matter," making the term "materialism" unclear. Noam Chomsky noted that materialism may change as science advances, and that assuming it won’t change is being too certain.