Physicalism vs Idealism (7 Main Differences)

In this guide, we will discuss Physicalism vs Idealism and some of the main differences we can find when talking about each perspective. Physicalism and Idealism are two points of view that have been a matter of discussion over centuries, which in term makes them a bit complex to grasp. However, here are some of the basics where you can see what each perspective entails and the main difference between them.

Physicalism vs Idealism

Here we will discuss Physicalism vs Idealism and the arguments that support each perspective. Additionally, we will talk about the main difference between Idealism and Physicalism explained by as follows:

“When used as nouns, idealism means the property of a person of having high ideals that are usually unrealizable or at odds with practical life, whereas physicalism means a philosophical position holding that everything which exists is no more extensive than its physical properties”.

Let’s examine then, the philosophical perspective of Idealism more than just having high ideals or unrealizable ones. In philosophy, Idealism argues that direct and immediate knowledge can only come from ideas or mental pictures. In contrast, physicalism argues that everything that exists is just an extension of the physical properties, meaning that there are no other ‘things’ than physical things. 

What is Physicalism?

As indicated by William Seager from The University of Toronto:

“Physicalism is a monistic metaphysics: it claims that there is only one basic kind of reality and it is physical in nature. The phrase ‘kind of reality’ is vague and ungainly; in the past materialist philosophers would have said there was only one kind of substance, or even more straightforwardly, only one substance: material, or physical, substance. But our grip on the idea that substance is the appropriate concept by which to describe basic reality has weakened. The rough idea remains clear enough: at the bottom, everything is physical.”

In other words, the main thesis here is that everything is physical, intended usually as a metaphysical thesis. The general premise is that the nature of the actual words conforms to the condition of being physical. However, physicalists don’t necessarily deny the existence of things that at first are not considered as physical such as items of biological, psychological or moral nature. But they insist that items are either physical or supervene on the physical.

Physicalism is sometimes known as materialism and both terms are used interchangeably but both have different histories. The term materialism was introduced long ago while the term physicalism was introduced into philosophy in the 1930s by Otto Neurath and Rudolph Carnap who were members of the Vienna Circle. Some philosophers argue how physicalism and materialism are distinct from one another since materialists argue that everything is matter and matter is conceived as an inert, senseless substance according to Berkley, while physics has shown how not everything is matter in the sense materialists see it.

Physicalism vs Idealism (7 Main Differences)

Types of Physicalism

Physicalism can be divided into two main categories, reductive and non-reductive physicalism. For the first category, we find that all mental states and properties can be or will eventually be, explained by scientific accounts of physiological processes and states. This is believed to be one of the most popular views from the 20th century. 

Additionally, we find four main types as Behaviorism, Type Identity Theory, Token Identity Theory and Functionalism. Behaviourism indicates that mental states are the descriptions of observable behaviour and as such, behaviours can be described scientifically without having to consider physiological or hypothetical constructs as part of the explanations of the mental processes. 

On the other hand, we find the Type Identity Theory or Type Physicalism, which argues that various kinds of mental states are identical to certain kinds of physical states of our brains. Unlike Type Identity Theory, Token Identity Theory argues that particular instances of mental states are identical to particular instances of physical states of the brain. 

Finally, we find functionalism which indicates that beliefs, desires, being in pain, etc., are considered mental states that have a functional role and are characterized in terms of non-mental functional properties. 

Non-reductive Physicalism

This second category within Physicalism argues that even if the brain is all there is to the mind, the terms used to describe and explain mental states can’t be reduced to the language and lower-level explanations of physical science. 

As indicated on, “Thus, mental states supervene (depend) on physical states, and there can be no change in the mental without some change in the physical, but they are not reducible to them”. Additionally, there are three main types, which are:

  • Anomalous Monism indicates that mental states or events are identical as physical events but the mental is said to be anomalous. For instance, the mental events are believed to be real, and identical with some physical matter but they are not regulated by strict physical laws. Therefore, even if all things are considered physical, not all physical things are necessarily mental.
  • Emergentism is considered a layered view of nature, where the layers seem to be arranged in terms of increasing complexity. 
  • Eliminativism or Eliminative Materialism holds that people’s common-sense understanding of the mind or what can be understood as ‘folk psychology’ is hopelessly flawed and will eventually be eliminated or replaced usually by neuroscientific explanations.

What is Idealism?

As indicated on, “The terms “idealism” and “idealist” are by no means used only within philosophy; they are used in many everyday contexts as well. Optimists who believe that, in the long run, goodwill prevail are often called “idealists”. This is not because such people are thought to be devoted to a philosophical doctrine but because of their outlook on life generally; indeed, they may even be pitied, or perhaps envied, for displaying a naïve worldview and not being philosophically critical at all”.

Subsequently, we find that the terms “idealism” and “idealist” can be used in several ways which will have a different meaning regarding the context. Additionally, we find different “idealisms” depending on the textbook or encyclopedia. However, we can find two important aspects of modern psychology that are considered fundamental to idealism:

  • The mind, spirit, reason, will, etc., meaning something mental, is the ultimate foundation of all reality. 
  • There is a conception where something else exists independent of the mind and everything we get to know about this mind-independent reality is held to be permeated by the activities of the mind that all claims to knowledge must be considered to be a form of self-knowledge. 


Kant is believed to be ones of the most influential philosophers who defended Idealism, considering himself as an epistemological but not ontological idealist. He was deeply impressed by Leibniz and was also impressed by the empiricist argument that everything we get to know about objects depends upon the experience we have with them. However, he also thought that both Leibnizian and Humean approaches lacked explanation in terms of the possibility of a priori knowledge, meaning the knowledge that goes beyond the mere analysis of concepts. 

Additionally, he doesn’t conceive synthetic a priori knowledge as leading to the reality or realism about an object nor he sees such knowledge as knowledge of the mind of God. 


For Schopenhauer and his form of epistemological idealism, behind the realm of appearances constructed following our own concepts of casualty, time and space, there is a unitary reality that is utterly irrational (or arational). 

Schopenhauer’s early work and publications include his modifications to Kant’s epistemology, while the later work accepts Kant’s idealist interpretation of this epistemology. Schopenhauer’s acceptance of his epistemological idealism combined with a non-rational ontological idealism can be seen in ‘The World as Will and Representation’. In his work, Schopenhauer accepts Kant’s argument that space, time and casualty are forms of our own representations that we know a priori. 

Why is this blog about Physicalism vs Idealism important?

As we have discussed on this blog about Physicalism vs Idealism, both perspectives are very different. For instance, we have that in philosophical terms, Idealism argues that direct and immediate knowledge can only come from ideas or mental pictures. In contrast, physicalism argues that everything that exists is just an extension of the physical properties, meaning that there are no other ‘things’ than physical things. Subsequently, we seem to have the realm of ideas and a physical and tangible realm where only physical things exist. 

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Frequently Asked Questions (FAQs) about Physicalism vs Idealism

What is the difference between idealism and materialism?

The difference between idealism and materialism is that idealism argues that ideas precede matter. This means that the existence of matter is because of an idea of its existence. In contrast, Materialism says that matter precedes the idea. This means that an idea of the existence of a material is the result of its physical existence which came first. 

What is the concept of idealism?

The concept of idealism defends the point of view where the only reality is the ideal world or the world of ideas. This means, there is no external reality composed of matter and energy since only ideas exist within minds. 

Are Physicalism and materialism the same thing?

Many people argue that physicalism and materialism are interchangeable terms, meaning practically the same thing. However, materialism is said to be a term that is going out of fashion being replaced by the concept of physicalism. Essentially, materialism is the doctrine that argues how matter is the only thing that exists and the various motions that happen between objects of matter. On the other hand, physicalism is the doctrine that defends the premise that only the physical exists. 

Is idealistic positive or negative?

Idealists are believed to have a positive pole of ‘coalescence’ and a negative pole of ‘abstraction’. There are divided opinions about whether being an idealist can be considered as positive or negative so it really depends on the perspective and the arguments. 

What is the purpose of idealism?

From an educational point of view, idealism aims to encourage individuals to discover and develop their full moral excellence to better serve society. The curricular emphasis is said to be the subject matter of mind in the fields of literature, history, philosophy and religion.

References “The difference between Idealism and Physicalism” “Physicalism” “Idealism”