Physicalism

Key takeaways

Physicalism belongs to physics; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Physicalism to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Physicalism from memory before moving on to harder problems.

Reference excerpt

In metaphysics, physicalism is the view that everything is physical, that there is nothing over and above the physical, and that everything supervenes on the physical. It stands in direct opposition to idealism, which asserts that reality arises from the mind. Physicalism is a form of ontological monism—a single-substance account of the nature of our universe's reality (physicalism is open to the possibility of different universes with different physics, and is open to the possibility of causal openness via a foundational logical mechanism or mechanisms), in contrast to "two-substance" (mind–body dualist) or "many-substance" (pluralist) views. Physicalism is closely related to naturalism, though important distinctions exist between them. Physicalism is also closely related to materialism, and has evolved from materialism with advancements in the physical sciences in explaining observed phenomena. The terms "physicalism" and "materialism" are often used interchangeably, but can be distinguished on the basis that physics describes more than just matter. Physicalism encompasses matter, but also energy, physical laws, space, time, spacetime, exotic matter, structure, physical processes, information, state, and forces, among other things, as described by physics and other sciences. According to the PhilPapers Survey 2020, physicalism is the majority view among philosophers, at 51.9%, but there is also significant opposition to it. Outside of philosophy, physicalism can refer to the preference or viewpoint that physics is the best or only way to render truth about the world or reality.

Definition of physicalism in philosophy The word "physicalism" was introduced into philosophy in the 1930s by Otto Neurath and Rudolf Carnap. The use of "physical" in physicalism is a philosophical concept and can be distinguished from alternative definitions found in the literature (e.g., Karl Popper defined a physical proposition as one that can at least in theory be denied by observation). A "physical property", in this context, may be a metaphysical or logical combination of properties which are not physical in the ordinary sense. It is common to express the notion of "metaphysical or logical combination of properties" using the notion of supervenience. Supervenience is the idea that there cannot be two events alike in all physical respects but differing in some mental respect, or that an object cannot alter in some mental respect without altering in some physical respect. The reason to introduce supervenience is that physicalists usually suppose the existence of various abstract concepts that are non-physical in the ordinary sense of the word.

Type physicalism

Type physicalism, also known as mind-body identity theory, holds that mental events can be grouped into types that correlate with types of physical events. For instance, one type of mental events, such as pain, correlates with a particular type of physical events, such as C-fiber firings. On this account, all instances of pain correspond to situations where C-fibers are firing. Type physicalism can be understood as the position that there is an identity between types: any mental type is identical with some physical type. A common argument against type physicalism is the problem of multiple realizability. Multiple realizability posits that the same mental state can be realized by different physical states. Another way to put it is that there is a many-to-one mapping from physical states to mental states.

Token physicalism

Token physicalism is the proposition that every particular mental event is a particular physical event (token physical event) but that there is no type-to-type mapping between mental events and physical events. The most common example of token physicalism is Davidson's anomalous monism. One of token physicalism's strengths is that it is compatible with multiple realizability. Mental states such as pain may be realized in any number of widely different physical events, without any type-like similarity between these physical events.

Reductive and non-reductive physicalism

Reductionism

In the philosophy of mind, reductionism is commonly understood as the reduction of psychological phenomena to physics and chemistry. In a simplified form, reductionism implies that a system is nothing but the sum of its parts. There are both reductive and non-reductive versions of physicalism (reductive physicalism and non-reductive physicalism). Reductive physicalism is the view that mental states are nothing over and above physical states and are reducible to physical states.

Emergence

Emergentism is a theory that became popular in the early 20th century. Notions of strong emergence are commonly found in accounts of non-reductive physicalism. A property of a system is said to be emergent if it is a new outcome of some of the system's other properties and their interaction while it is itself different from them. Emergentism emphasizes that the whole is more than the sum of its parts. In the context of the philosophy of mind, emergence is often thought to entail property dualism.

Arguments against physicalism

Knowledge argument

Though there have been many objections to physicalism throughout its history, many of them are concerned with the apparent contradiction of the existence of qualia in an entirely physical world. The most popular argument of this kind is the so-called knowledge argument as formulated by Frank Cameron Jackson, titled "Mary's room". The argument asks us to consider Mary, a girl who has been forced to discover the world from a black-and-white room via a black-and-white television monitor throughout her life. She has access to books containing all physical knowledge. During her time in the room, she learns all the physical facts about the world, including all the physical facts about color. To a physicalist, it would seem that this entails Mary knowing everything about the world. But once she is let out of the room and into the world, it becomes apparent that there were things Mary did not know about the world, such as the feeling (the qualitative experience) of seeing color. If Mary did not have such knowledge, how can it be said that everything supervenes upon the physical?

… excerpt ends here. Continue reading the full article.

Worked examples

Example 1 — a first encounter with Physicalism

Start with the simplest possible case. Write down what Physicalism claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In physics, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Physicalism before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Physicalism ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Physicalism

In research: Physicalism appears in physics research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Physicalism in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Physicalism is common in secondary-school and first-year university syllabi. It links to neighbouring topics Metaphysical theories, Ontology, Philosophy of physics, so understanding it makes those chapters shorter.
In everyday life: Look for Physicalism outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

How to study Physicalism in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Physicalism means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Physicalism out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Physicalism in simple terms?

In metaphysics, physicalism is the view that everything is physical, that there is nothing over and above the physical, and that everything supervenes on the physical. It stands in direct opposition to idealism, which asserts that reality arises from the mind.

Why does Physicalism matter?

Because it connects several physics ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Physicalism?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Physicalism.