An Argument for Idealism

Written at 2022-12-24

This essay was originally written for the ‘Introduction to Philosophy I’ (PHIL103) course at Bilkent University, where we delved into various branches of philosophy, including consciousness. It reflects some of the thought processes that arose as I grappled with these philosophical questions. It’s important to note that this essay is not an exact reflection of my personal beliefs, but rather an exercise in argumentation.

Despite this, I believe the arguments presented in this essay hold value and are worth exploring. My hope is that this essay provides you with insight and provokes thought, and that you find value in engaging with the ideas presented here.


Believing in a particular framework that describes the nature of existence, known as an ontology, can greatly influence an individual’s perspective on life and their actions. Three such ontologies are Physicalism, Dualism and Idealism.

Physicalism states that all phenomena can be explained in terms of physical concepts. If a person believes in Physicalism, they may prioritize material possessions and physical experiences, and focus on achieving practical goals. This belief can also affect their beliefs about the afterlife and the nature of the self.

Dualism, on the other hand, is a view that posits the existence of two fundamental and distinct kinds of substances or principles: matter and mind. This view is similar to Physicalism in that both agree that there exist physical objects. But is different in the sense that it holds that the mind and the body are distinct entities that cannot be reduced into one another.

In this article, I argue that we have sufficient reason to believe that objects that exist are not physical, refuting both Physicalism and Dualism. I do this by first showing that the existence of physical objects cannot be known, and then combining this belief with the principle of parsimony, also known as Ockham’s Razor. As a result, this argument supports the ontology of Idealism, which is the view that reality is ultimately mental in nature.


Let me present you the outline of my argument:

P1. If agents can know whether something exists, then they know so a priori or a posteriori.
P2. Agents don’t know a priori whether physical objects exist.
P3. Agents don’t know a posteriori whether physical objects exist.
C1. Agents cannot know whether physical objects exist.
P4. If existance of a thing cannot be known and assuming it does not give us more explanatory power than what we are left without it, then there is no reason assuming it exists. (parsimony principle)
P5. Assuming existence of physical objects does not give us more explanatory power than what we are left without it.
C2. There is no reason for assuming that physical objects exists.

The first premise (P1) is very easy to see, if not self-evident. By definition, a priori knowledge means the knowledge we gain without experiencing whereas a posteriori knowledge means the knowledge we gain with experience. It is either one or the other.

The real challenge is to show that P2 and P3 are true.

For (P2), we can say that agents’ understanding of physical objects are fundamentally acquired through the sensory experiences they have. For example, physicists do not know the behavior of an electron until they perform certain experiments, such as observing its interactions with other particles or measuring its properties using certain equipments.

Also, keep in mind that a priori knowledge is the knowledge that is not contingent. Whereas it is not possible to conceive a triangle that has 4 sides, it is, possible to conceive physical objects not being exist.

(P3) can be deduced by claiming that a representation is not the same thing as the thing it represents, and that what we don’t deal with physical objects themselves, but with their representations.

Representation of a thing, is not the same thing as it represents. For example, a wine in a menu is not the same thing as a wine, for you cannot drink the wine in a menu but the wine itself. The words we use for describing stuff, the concepts we have in minds are also representations of things. When it comes to representations, there always are stuff that you can do with one but not with another.

Furthermore, our experiences of the world are limited by the capabilities of our senses. We can only perceive a small range of colors and other sensory information, and this information is not experienced directly but is interpreted by our brains. This is why we can be susceptible to optical illusions and other forms of sensory deception. Additionally, our experiences of physical objects are not of the objects themselves, but of their representations in our minds. This means that We don’t deal with physical objects themselves, but with their representations.

This is analagous to one of the metaphors Donald Hoffman, a cognitive scientist, likes to use. The sensory systems that humans possess (such as touch, smell, sight, sound, and hearing) function as a user interface that hides the true complexity of reality (e.g. the circuits and voltages in a computer) and allows individuals to control and interact with it without needing to understand it. He compares this to the way that a desktop interface on a computer hides the inner workings of the device and allows users to control it through icons and actions like dragging and clicking (Hoffman).

(P4) is also referred as principly of parsimony, or Ockham’s Razor. The principle helps us to simplify our thinking by reducing the number of competing frameworks that compete with each other. There are two reasons I follow this reason.

Firstly, whether we know reality is necessarily simple or not, unless there is a good reason or advantage to believe a concept over other explanations, we are justified in not believing it.

Secondly, we already use this principle a lot when doing science. In general, the massive embracement and success of this principle in scientific fields provides a reason to think that it is a useful and reliable guide for eliminating certain hypotheses.

Finally, let us consider (P5),

In P3, we demonstrated that our understanding of the world is derived from our experiences and observations. This is based on representations, not the things themselves. We do not obtain these representations after having the concept of physical objects; rather, it is the other way around.

Even without accepting the existence of physical objects, we are already capable of conducting science. Our assumption of the existence of physical objects is simply a mental shortcut that we use to try and comprehend our surroundings. However, we do not necessarily need this assumption.

Moreover, all of the regularities that we observe in the world would still be possible even if we only accepted the existence of mental substances. In this way, what we refer to as physical objects would be fundamentally a type of mental substance. This does not violate Ockham’s Razor, as there are already strong arguments, such as Descartes’ cogito ergo sum, that support the existence of mental things.


Now that I have proposed my position in advance, it is now a good time to consider some of the potential criticisms and misconceptions that could be raised against this position.

What is it that is represented?

“If physical objects does not exists, and the only thing that we deal with is physical representations, then what is it that is represented? There cant be a representation of a thing that does not exist.” one might say.

Yes, I agree with the part that if something is represented, then a thing exists. The part that I don’t agree with is that physical representations are the representations of objects that are physical objects which are independent of mind.

It is now a great time to clarify what I mean by physical objects and physical representations. In this argument, I used the expression “physical objects” not in the sense that a substance that can be fully explainable through physics. If that would be the case then it would be wild that I claim such objects does not exist. By physical objects, I refer to objects that exists independently of mind. Physical representation, on the other hand, are the kind of representations that are made in Physics. This representations, by themselves, does not require what is required to be independent of mind.

In essence, idealists does not necessarily reject physical objects does not exist in the sense that there are objects which can be explained by physics but in the sense we prescribed above. When certain a spiritualist says “Matter is a way of seeing, not something that is seen” (Spira) they seem to be agreeing that there exists objects that can be understood from the perspective of Physics but disagree with the part that those objects are abstract, mind-independent substances by themselves.

Ockham’s Razor is not reliable

The argument relies on Ockham’s Razor, which states that the simplest explanation is most likely to be true. However, this assumption may not always hold true. Some may argue that we do not have sufficient evidence to assume that reality is simple.

Although one can believe that reality is not supposed to be ontologically simple, they can still be epistemically justified to favor the simplest explanation when faced with multiple possibilities. This does not have to be the case because the reality is ontologically simple, but rather, it is the best we can do: In the absence of other compelling evidence when comparing seemingly equivalent explanations, it is already justified to choose one of the theories randomly, so why not just choose the simpler one?

Direct Perception of Physical Objects

It is possible to reject P3 by saying that direct perception of physical objects is possible. One could say that a representation of a thing can be seen as identical to the thing itself if the function of the representation is the same as the thing it represents. For example, one might argue that if a photograph of a cup were able to serve the same function as the actual cup it represents, then they could be seen as identical.

However, this approach ignores all the other aspects of entities besides their functions. Even though the photograph and the cup may function in the same way, they are not necessarily the same thing unless they are made of the same substances and share the same inner workings.


In conclusion, I have come to the conclusion that there is no reason for assume that physical objects exist according to the principly of parsimony. I have done this by first arguin that agents cannot know whether physical objects exist. And then showing that assuming the existence of physical objects does not give us more explanatory power than what we are left without it.


“The Case Against Reality.” Performance by Donald Hoffman, Youtube, 8 Sep 2019,, Accessed 24 Dec. 2022.

“Matter Is a Way of Seeing.” Performance by Rupert Spira, YouTube, 12 May 2015, Accessed 24 Dec. 2022.