Idealism Pt. 1: Berkeley’s Subjective Idealism

Author: Addison Ellis
Category: Historical Philosophy, Metaphysics, Epistemology
Word Count: 1000

Editor’s Note: This essay is the first of two essays in a series authored by Addison on the topic of philosophical idealism. Part 2 on Kant’s Transcendental Idealism can be read here.

We often take it for granted that we have some knowledge about the way reality is. For instance, it seems clear to me that I know there is a computer screen directly in front of my face, and I believe it is clearly true that I know how to get to the refrigerator from where I currently sit. But what is the nature of the computer screen and the refrigerator? Common sense tells us that they are bundles of physical stuff and that our minds have become adapted, perhaps through a process like evolution, to knowing about and acting with respect to them.

Idealism, on the contrary, is the view that what reality is like depends upon the way the mind works. There are many distinct versions of idealism in the history of philosophy, and we will consider three of the most important versions over three distinct installments: Berkeley’s subjective idealism, Kant’s transcendental idealism, and Hegel’s absolute idealism. This, then, will be part one of a three-part installment on idealism, and we will start with George Berkeley’s subjective idealism.


1. Two Arguments for Berkeley’s Subjective Idealism

George Berkeley, an 18th-Century Irish philosopher, held that esse est percipi, or “to be is to be perceived.” When I perceive a black dog, according to many philosophers in the early modern period, I am in possession of a representational state – that is, my mind is affected by a physical thing, the dog, which in turn causes my mind to generate a mental representation of the dog. What I perceive, then, is really only a representation, from which I infer the existence of the thing represented. This is called indirect realism.

Berkeley challenged this traditional picture in the following way.1 First, when we take a representation to accurately represent an object in the world, we do so on the assumption that the representation resembles the object in some way. But, Berkeley argues, we are in no position to say that our ideas resemble anything other than other ideas. According to Berkeley, we cannot compare ideas with material objects since to have knowledge of a material object would require that we know it via some idea. Thus, all we ever encounter are ideas themselves, and never anything material.

If Berkeley is right, then we never have knowledge of anything material whatsoever; we only ever know our own ideas. This is part of a larger attack in which Berkeley argues that we are not entitled to believe that matter exists, in which case the only things that do exist include minds, ideas, and God. Berkeley is putting forth a view that is sometimes called subjective idealism: subjective, because he claims that the only things that can be said to exist are ideas when they are perceived. Thus, my black dog exists only when I am currently in possession of the idea of my black dog. If I leave my dog behind when I walk to the store, she no longer exists, and so her existence is purely dependent upon a subject’s perception of her.

In addition to the resemblance argument above, and to strengthen his attack on realism and materialism, Berkeley also argues that matter is impossible.

The basic idea goes like this: Matter is defined as physical stuff which can exist independently of our minds. We ordinarily take matter to be the stuff that makes up reality, and this stuff is supposed to go on existing whether we are perceiving it or not. That is, we think of matter as stuff that can exist unconceived. But we can never conceive of matter except through some idea. If so, then we cannot conceive of matter as something unconceived. In fact, it would be absurd to say so, since necessarily in conceiving of matter, we are conceiving of an idea, and surely we cannot conceive of an idea that is unconceived. If all of this is true, then, Berkeley argues, matter as it is defined is impossible.2 If matter is impossible, then no material objects exist, and it is only possible for minds, ideas, and God to exist.

2. Problems with Subjective Idealism

If Berkeley is right, and things exist only insofar as they are ideas being perceived by a mind, then there were never physical objects like mountains and animals before minds capable of knowledge (i.e., minds like ours) came into existence. Since things, for Berkeley, exist only insofar as they are being perceived (esse est percipi), and since no minds were perceiving anything millions of years ago, then nothing would have existed millions of years ago, if Berkeley is right. This is an unsettling thought, since it directly conflicts with both common sense and our best scientific worldview.

However, Berkeley may be able to avoid such a problem by suggesting that our ideas continue to exist in the mind of God even when we cease to possess them ourselves. When we have ideas, especially perceptual ones, they seem to be passive with respect to our minds. That is, in perception we seem to have little choice in what ideas we encounter. Because ideas are passive, they do not cause themselves. Additionally, since ideas are always possessed by a mind, and since our minds do not seem to simply produce their own ideas (since we passively receive them), they must be given to us from another mind. For this reason, Berkeley believes (i) that God exists, and (ii) that our ideas have their origin in the mind of God. If this is true, then arguably my dog does not simply pop out of existence when I cease to perceive her, since all our ideas are ultimately held in the mind of God.3

3. Conclusions

We should take away three important points from this essay. First, idealism is the view that the way reality is depends upon the way the mind is. Second, one version of idealism, Berkeleyan subjective idealism, holds that all there is are ideas, the minds that possess those ideas, and God.4 Third and finally, while Berkeley’s view is not without its problems, his arguments are compelling and worth taking very seriously.


Berkeley rejects both indirect and direct realism, to be more precise. In traditional philosophical parlance, it is common to define realism as the view that there exists a mind-independent reality. If this is what realism means, then no idealist is a realist. Curiously, as we will see with Kant’s transcendental idealism, a distinction can be made between what Kant calls transcendental realism and empirical realism. Kant believes that he can be an empirical realist and a transcendental idealist.

See Dialogue Two in the Three Dialogues of Hylas and Philonous.

This is by no means the end of the discussion. As we will see in the next installment, Kant has more objections to Berkeley’s subjective idealism.

God is a kind of spirit or mind, but one that is infinite rather than finite like us.


Berkeley, George. Three Dialogues between Hylas and Philonous. Indianapolis: Hackett 1979.

Downing, Lisa. “George Berkeley.” Stanford Encyclopedia of Philosophy. Stanford University, 10 Sept. 2004. Web. 07 July 2014. <>.

About the Author

Addison Ellis is lecturer at the University of Illinois at Urbana-Champaign, where he earned his Ph.D. from. He holds an M.A. in Philosophy from the University of Colorado at Boulder and a B.A. in Philosophy and Psychology from the University of Illinois at Urbana-Champaign. He is currently interested in philosophy of mind (especially problems of intentionality), epistemology (especially the role of philosophical intuitions in philosophical practice), Kant, and post-Kantian philosophy.

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