Reading Time: 11 minutes By Joreth (Own work) [CC BY-SA 3.0 (], via Wikimedia Commons
Reading Time: 11 minutes

Time to get back to some philosophy. Today we will be briefly looking at the position of idealism as developed by many German philosophers, but including the famous Bishop Berkeley and then taken on by Moravian philosopher Edmund Husserl and other Continental philosophers.

Defining our terms

Here are some pretty basic definitions of some useful terms:

Idealism: The belief that the mind and ideas are the primary source of existence; that the physical realm is either secondary or, in the extreme, doesn’t exist.

Materialism: The belief that matter is primary and the mental realm is a product of the material realm.

Rationalism: The belief that the rational mind is the best way of knowing things – perhaps that the mind is more trustworthy than the senses.

Empiricism: The belief, opposing rationalism, that the senses are the best way of knowing things, as such observing the external world. Truth can be confirmed by sense data.

(It is worth noting that you can be an empiricist idealist but not a materialist idealist.)

Philosophers will define “truth”, “fact” and “knowledge” differently. For me, knowledge is a true belief we have about a proposition. The problem is in establishing truth – the correct correlation between a belief of the external world, and the reality of the external world. For me, using something called the Correspondence Theory of truth, a true proposition is one that corresponds 1:1 to the objective world outside of our minds. The problem is establishing that correspondence indubitably since we cannot extricate ourselves from our own subjective experiences and we also cannot indubitably know we are not brains in vats having our senses input directly into our brains.

Hence Descartes’ cogito ergo sum – I think; therefore, I am. The only thing we can indubitably know is that “I” (whatever that may be) exist.


Phenomenology is the study of the experience of objects. Because experience is subjective, there is this tension between the experience and knowledge of the external world.

Immanuel Kant took Descartes idea – one that looked inward at the subject to be concerned with rationalism – and looked at this relationship of subject to object. Kant recognised that there was a limit to our subjective minds knowing these objects. In his Critique of Pure Reason, he delineated a difference between what he called phenomena and noumena. Phenomena are objects that are interpreted through the subjective mechanisms of human consciousness and senses. Noumena are what he called “things-in-themselves”. Kant declared that humans are unable to access this noumenal knowledge, since it is only interpretable through our subjective senses.

Let me use an analogy. Imagine a human and a bat looking at or sensing a moth. Each has our own subjective senses and experience the moth in very different ways. Even our sense of colour will be different.

We can extrapolate this sensory and experiential difference onto two different humans. Maybe our subjective experiences of a moth may not be that different and maybe they may. Our knowledge of all things may well be different and contingent upon our cognitive faculties: our senses and our consciousnesses. None of these agents (the humans or the bat) know the thing-in-itself (what Kant called the Ding an sich), all have different “knowledges” of the same object or thing. Kant would see humans as making sense out of the world around us – out of the phenomena – by using reason and our conscious deliberations in a process he described as transcending the observations. However, to truly know these objects, these noumena, is beyond the capability of such transcendental analysis. Therefore, these objects (our universe) remain fundamentally unknown and unknowable.

Let’s now move onto idealism proper, as Kant’s thinking was developed by Johann Fichte and Friedrich Schelling, amongst others, before being built on by Georg Hegel.

Hegel, in contrast to Kant, asserts that the categories that we bring to bear on the world can indeed constitute actual knowledge. This is based on Hegel’s criticism that the search for knowledge entails first being able to set out what knowledge ontologically is before actually making claims of knowing anything. However, this sequence, Hegel believed, goes down the path of an infinite regress (remember our trilemma) making its foundations self-contradictory. His phenomenology attempts to dissolve this problem by seeing the mind and the thing as, in some sense, unified. He found Kant’s “world in itself” as somewhat meaningless. As Paul Redding in the Stanford Encyclopedia of Philosophy states:[1]

Like Kant, Hegel thinks that one’s capacity to be “conscious” of some external object as something distinct from oneself requires the reflexivity of “self-consciousness,” that is, it requires one’s awareness of oneself as a subject for whom something distinct, the object, is presented as known. Hegel goes beyond Kant, however, and expanding on an idea found in Fichte, makes this requirement dependent on one’s recognition… of other self-conscious subjects as self-conscious subjects, and, moreover, on one’s recognition of them as similarly recognizing oneself as a self-conscious subject. Such patterns of mutual recognition constituting “objective spirit” thereby provide the matrix within which individual self-consciousnesses can exist as such…

For Kant, the practical knowledge of morality, orienting one within the noumenal world, exceeds the scope of theoretical knowledge which had been limited to phenomena. Hegel, however, thought that philosophy had to unify theoretical and practical knowledge, and so the Phenomenology has further to go.

Hegel rejected Kant’s thing-in-itself as being self-contradictory because a thing must be an object of our consciousness if it is to be an object at all. As Fichte and Hegel believed, a thing is only a thing when it is something for us. The thing-in-itself is actually a product of our thought. This new kind of German Idealism (where idealism is the belief that fundamental reality is intellectual rather than material) moved idealistic thinking along since Hegel and his contemporaries were willing to dissolve the distinction between being and thinking.

Kant believed objects were mind-independent, just that we could not know them. This new wave of idealists, on the other hand, saw a universality to conscious thought, not necessitating a distinction between the mind and the object. There is a circularity involved in this process (which bypasses the regression mentioned earlier) that is necessary to address. Hegel, in believing that the Whole Truth could be known, set out to show that the “I” was absolute, not contingent upon nature (it was something real). If the “I” were dependent upon nature, it would thus adhere to a form of duality that he saw as contradictory. Hegel has the object that Kant says we cannot know in itself as existing in our conception. That nuomenal world beyond thought is also dependent upon thought.

For idealists, there are no things-in-themselves. What we call objects and events are actually constellations of perceptions so that there exist only two things: perceptions and perceivers.

This shows the similarity between Descartes cogito – where in order to doubt one’s existence, one must exist – since the idealist says that a mind-independent object cannot “exist” because in order to consider it, we are using our minds. This is rather similar to the idea that there is no sound of a tree falling in a forest if there is no one to conceive of the sound. There is no tree at all if it is not in anyone’s conception.

Criticisms of idealism

I won’t bore you any more on Hegel; there is so much to say. Kant can be pretty complex – Hegel ups the ante considerably. And then there is the philosophy of Edmund Husserl to consider. There are also different types of idealism because…philosophy.

Does it hold, this notion that the mental is primary, and perhaps even all there is in existence?

There is certainly this idea that the universe is different to how it intuitively seems.

Idealists will generally claim that they consider matter to be an abstraction that has no purpose, that it is an extraneous abstraction that does not serve a function and has no evidence for it. It’s not that one can disprove matter but that is existence is based on faith and serves no pragmatic use. Why should we bother believing in matter given that there is no evidence for it and as an abstraction it serves no purpose? There is a sort of Ockham’s Razor here whereby multiplying unnecessary layers of explanation (here, physical abstraction) is not required, less parsimonious and thus less desired, less simple and less elegant.

To this, I would answer with a challenge. External to your mind is your brain. I recommend sticking a fork through your eye socket and into your brain, idealist, to see if the mind and consciousness is affected. I think there is definitely a usefulness to thinking that the external world exists. the mental supervening on the physical is a cornerstone, for me at any rate, of realist thinking.

Idealism seems to create a mystery for why we appear to live in a world of things that exist outside of our perceptual minds. If I hide a ball under a blanket, we all assume (even toddlers) that the ball is still there, even though you cannot perceive it. And it is, which makes sense of the ball being there when I lift the blanket. Bishop Berkeley, a famous idealist, tried to solve this intuitive problem for idealism by saying the external world does exist in the mind of the Great Perceiver: God.

I’m not all that sure of the God concept, so I don’t buy into this philosophy.

Other minds also present a problem for idealism. As an ontological realist, I assume that other minds are resultant from other brains and I communicate with them on the basis that they are similar to my brain and mind, allowing pragmatically for communication. I don’t go about my daily business assuming that other minds are merely a figment of my perception. As philosopher Arthur Schopenhauer observed of idealism’s running counter to common sense:[2]

In spite of that one may say, nothing is so persistently and ever anew misunderstood as Idealism, because it is interpreted as meaning that one denies the empirical reality of the external world. Upon this rests the perpetual return to the appeal to common sense, which appears in many forms and guises; for example, as an “irresistible conviction” in the Scotch school, or as Jacobi’s faith in the reality of the external world. The external world by no means presents itself, as Jacobi declares, upon credit, and is accepted by us upon trust and faith. It presents itself as that which it is, and performs directly what it promises

Indeed, the faith in matter is equivalent to a faith for idealists in other minds. Since we struggle to control our realities and our own minds, I find idealism a pretty difficult concept to give credence to. Not only can I now control everything, I also don’t know everything. See The Problem of Other Minds.

To add to this, there are further issues with idealism, most notably its poor explanatory power:

There is a high degree of consistency in the passive sense data or certain “objects of perception” that we cannot control, both between different people and in the same mind over time….

It would appear that the consistency requires an explanation….

(1) why do we have a conscious existence with a high degree of consistency and what looks like external constraints facing us?;

(2) where do minds come from?;

(3) in fact, how can you justify the view that other minds even exist? (why doesn’t non-theistic idealism collapse into solipsism?);

(4) if the idealist accepts that other minds exist, do animals have minds?

One could add a welter of other questions to these, but the conclusion is clear: the explanatory power of idealism is feeble and weak (Musgrave 1988: 241), and the idealist must shrug his or her shoulders and proclaim that we cannot even begin to seriously answer these questions.

By contrast, the indirect realist materialist can provide convincing answers to all these questions from our best scientific theories and inductive argument.

What do I believe? Well, the previous source quoted also includes an account of my position:

George Berkeley’s (1685–1753) philosophy of subjective idealism (which he called “immaterialism”) has two bold and fundamental assertions about reality:

Proposition (1): that the only things that exist are (i) minds and (ii) objects of perception (ideas), and

Proposition (2): the objects of perception only exist at the same time when they are perceived by a mind (Stoneham 2009: 119).

It follows from this that the external world of matter we normally think exists does not exist, under Berkeley’s ontology.

I think any non-dogmatic realist would accept that it is possible that these propositions might be true. Also, I doubt whether any idealist can prove such propositions with necessary or apodictic truth. Also, I assume that a non-dogmatic idealist would also admit that it is possible that the realist position might be true.

Realists and materialists who reject Berkeley’s idealism come in two main groups:

(1) indirect or representative realists (and modern scientific realists), and

(2) direct realists. (Stoneham 2009: 120–121).

Direct realists would argue that actual physical objects in the external world are amongst the “objects of perception,” whereas the indirect realists argue that physical objects in the external world are not amongst Berkeley’s “objects of perception.”

Thus it is possible for an indirect realist to accept Berkeley’s proposition (2) above, but reject as untrue proposition (1) above.

On realism, I take position (1): the indirect or representative realist view. This states that it is highly probable that there is an external physical world of objects or things/events that corresponds indirectly to some objects of perception in the sense that some objects of perception are causally dependent on real objects.

But we do not have direct access to the external objects of reality, but only to some conscious “objects of perception” that are causally dependent on them. That is to say, the objects and events of the world of matter and energy described by science are not objects of immediate experience/“objects of perception”.

So the indirect realist/materialist’s inductive argument does not say that the external object and the internal “objects of perception” are absolutely equivalent (as noted in Stoneham 2009: 121).

The human mind’s “objects of perception” are representations (with colour sensations, shapes and so on) of sense data from the external world such as, for example, from the swarm of particles called a tree, and this system of internal representation is the product of Darwinian evolution, and one could conceive of a mind capable of representing the same tree in different ways from different data beyond the visible spectrum (e.g., infrared or x-rays).

Furthermore, the actual qualities we perceive in our minds like green and red are not qualities of the actual object existing in material reality, but are merely causally dependent on them to some extent (e.g., light waves reflected off the object are the causal factor for perception of colours).

So we see that the indirect realist makes a crucial distinction between (1) “objects of perception” and (2) external objects that we do not experience directly. Our argument for the existence of an external world of events/objects is an inductive one based on empirical evidence. Its truth is at most very probable, not certain.

Final remarks

It seems to me that the external world exists. It is also a coherent idea and one that the entirety of science is built on. I have no good reason to think that the mental realm is all there is, or that it is primary in a way that is meaningful. Not only do I think that idealism is not an accurate appraisal of reality, but I don’t think that it is all that useful.

Plus, I don’t fancy sticking a fork into my brain and testing the idea.

That said, for further reading in defence of idealism, and attempts to eliminate or refute these criticisms, see Bernardo Kastrup’s “On the Plausibility of Idealism: Refuting Criticisms“. He seeks to show that idealism is at least plausible. His conclusion, to whet your appetite, is as follows:

Idealism is a unique ontology in that, unlike physicalism and panpsychism, it asserts that physical structures are circumscribed by consciousness, as opposed to the other way around. Yet, analytic philosophy has traditionally considered idealism implausible. In this essay, I have argued that the alleged implausibility of idealism is based on misconceptions, such as:
• Unfounded intuition—e.g. taking the concreteness of the world to indicate its independence from consciousness, or asserting the implausibility of universal inner life;
• Lack of philosophical imagination—e.g. assuming that multiple private minds and a stand-alone world cannot be coherently reduced to a single universal consciousness;
• Demonstrably wrong assumptions—e.g. that all mental activity is acquiescent to volition;
• Question-begging—e.g. arguing that different people cannot share a dream because their bodies are separate, and arguing that the universe cannot be in consciousness because it existed before conscious life first arose;
• Anthropomorphization—e.g. taking all conceivable processes in consciousness to necessarily be unstable and disorderly;
• Failure to understand the implications of idealism—e.g. asserting that a field of phenomenality outside personal psyches is equivalent to a physical world outside phenomenality;
• Unexamined assumptions—e.g. that the physical is in some sense distinct from, yet causally effective upon, the phenomenal;
• Conflation—e.g. conflating consciousness proper with self reflection, conflating unconsciousness with failure to recall phenomenality, and conflating idealism with solipsism.
As such, idealism is an entirely plausible ontology that may offer the most parsimonious and explanatorily powerful option yet to make sense of reality.

Perhaps I will return to this list in a future post.


[1] Redding, Paul (2010), “Georg Wilhelm Friedrich Hegel”, The Stanford Encyclopedia of Philosophy,

[2] Schopenhauer, Arthur (2015), The World as Will and Idea (Vol. 2 of 3), VM ebooks.

Stoneham, Tom. 2009. “Berkeley. Arguments for Idealism,” in Robin Le Poidevin, Peter Simons, Andrew McGonigal, Ross Cameron (eds.), The Routledge Companion to Metaphysics. Routledge, London and New York. 119–130.


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Jonathan MS Pearce

A TIPPLING PHILOSOPHER Jonathan MS Pearce is a philosopher, author, columnist, and public speaker with an interest in writing about almost anything, from skepticism to science, politics, and morality,...