[Essay] Can reality be known as it is?

Guillaume Hansali
Guillaume Hansali
[Essay] Can reality be known as it is?

Essay's question

Can reality be known as it is? What is the role of the senses in the quest for 'real' knowledge?

Essay written for the Introduction to Philosophy online course at Oxford: https://www.conted.ox.ac.uk/courses/introduction-to-philosophy-online
Constraint: 1500 words.


I know that Sherlock Holmes lives on 221B Becker Street. It is a fact. But it isn't real.
Can I be certain that something is real? Moreover, is my belief that I perceive things as they really are justified?

I will introduce a broad definition of reality and then propose a more practical interpretation for our argument.

Considering both a priori and a posteriori knowledge acquisition and the role of the senses in such acquisition, I will argue that, within the suggested interpretation, we cannot know reality as it is in a strictly ontological sense.

Lastly, I will suggest that within our epistemological limitations, we may be able to acquire knowledge about a more 'human' reality.


According to the Oxford Language dictionary, reality is 'the state of things as they actually exist, as opposed to an idealistic or notional idea of them.'
Sherlock Holmes is a fictional character of the imagination, an idea. He is, therefore, not real.
The definition additionally excludes any representation of things; while the cat I saw in the street this morning is real (allegedly), my mental representation of it is not.

Only things that exist are real, and therefore, reality is the sum of all that exists.

Can reality be known as it is? It may be more practical to break this question down as follows.
(1) can we know whether something exists?
(2) if something exists, can we know it as it is?
(3) can we know everything in existence?

The laws of physics tell us that it is impossible to retrieve information beyond the cosmological horizon. Some things may exist beyond the horizon of which we cannot know anything, and therefore we cannot know with certainty everything in existence.

With (3) ruled out, I will narrow the scope of our 'quest to real knowledge' to (1) and (2), namely, can we know whether something exists and if it does, can we know it as it is.

There are two forms of knowledge; a priori, which can be derived from reason alone, and a posteriori, which is acquired only through experience. I will investigate both forms.

Can reality be known a priori?

Can we know whether something exists a priori?
Descartes famously argued that there is only one thing he can know exists for sure, and a priori: his own existence (Descartes, Guttenplan, p.32).
I can think; therefore, at least my mind exists. Anything external to my mind, my body, and the outside world can only be perceived through my senses which may be deceiving me.

Cartesian dualism poses a serious epistemological obstacle to our acquisition of knowledge about reality.
In order to move forward, I will consider the mind/body problem irrelevant and, while being aware of the non-triviality of such an assumption, assume that there is a material world that exists outside of our minds.

What can we know about the world a priori? Not much, there would seem, besides our existence in it; to know what is in the world, we need to observe it.
Assuming we have observed the world, can we acquire new a priori synthetic knowledge from empirical observations? That seems to be the case, and blacks holes or quarks are good examples. We have never observed directly any black holes, but we have deducted their existence a priori from separate observations and the application of the laws of physics.

To be sure, many laws of physics are theorizations of physical observations acquired a posteriori. Nevertheless, once formulated, they can be applied a priori.

So it appears as though we can expand our knowledge of reality a priori by inference. However, we would be making another non-trivial assumption, namely, that the laws of physics are constant over time and space.
Hume argues that such an assumption is far from being self-evident and that any 'inductive inference' we perform when we infer the unobserved from the observed is based on beliefs without legitimate grounds (Henderson, Lea, Spring 2020).

Besides our own existence, we cannot know a priori whether something in the external world exists, let alone know it as it is; 'real' knowledge can be acquired only a posteriori.

Can reality be known a posteriori? The role of our senses

Through experience, we can acquire information about the world around us.
Our senses are the interface with which we observe it. They receive diverse stimuli and relay them to our brain, which processes them and constructs a mental representation.
Within our mental representation, we can discern different objects or things of interest. I can right now clearly distinguish the glass from the table on which it is laying, and I can infer that both objects exist, a posteriori.

Do I perceive the glass as it really is? In other words, is my mental representation of the glass faithful?

A realist such as Locke would argue that there are certain characteristics that he calls primary qualities of which our representation is identical to those from the observed entity, such as shape, position, motion, and solidity (Locke, Guttenplan, p.323).
In contrast, secondary qualities, such as color, smell, and texture, do not belong to the object itself but are purely subjective phenomena (Locke, Guttenplan, p.324). Colors, for example, do not exist outside of our perception of them; they are the result of the stimuli caused by light reflection on the object observed and how that object alters the light on reflection.

The realist view claims that objects so indeed exist, independently from our cognition of them (Miller, Alexander, Winter 2019) and that we have an accurate mental representation of their primary qualities; we can therefore know that they exist, and if we could imagine them colorless, odorless, and textureless, we would have a pretty accurate representation of reality.

Berkeley objects to this conclusion. Can we really imagine colorless and textureless objects? How could we recognize the shape of a transparent object? Our mental representation of an object cannot be directly produced by that object, and therefore, objects cannot exist independently of our minds (Blackburn, p.247).

Physics and the use of a powerful microscope tell a similar story.
The world is not a collection of discrete objects but a continuous distribution of atoms of varying density; zooming on any material, including air, to an atomic level would show essentially empty space between countless atoms, with no clear delimitation between objects.

If objects cannot be discerned from a continuous distribution of atoms, they may not exist in themselves as distinct entities, but only in our minds, in our mental representation.

The above realization goes against our most fundamental intuition about reality. Even if I accept that I do not perceive things as they really are, I can still clearly distinguish and recognize objects, so they must exist.

Kant suggests that, in fact, I do not perceive objects; I objectify my perceptions by projecting pre-conceived, a priori concepts of reality onto the objects of perception. My mental representation of an object (phenomenon) may, therefore, not resemble the object as it is in itself (noumenon) (Blackburn, p.257).

If the objects I perceive are simply products of the inner workings of my mind, while matter may exist, things themselves may not.
I cannot know with any degree of certainty whether something exists.

As we have seen, I cannot know (3) everything in existence, (2) how things are in themselves, and even (1) whether something actually exists.
I conclude, therefore, that reality cannot be known as it is.

Redefining reality

I may have portrayed a bleak picture of realism, but there is some light in the darkness.

Markus Gabriel, a leading figure of new realism, offers a different epistemological approach to reality. Instead of a single reality, there would be an infinite collection of realities that he calls 'fields of sense,' or domains in which 'something […] appears in a certain way'. (Gabriel, p.69)
Something exists (and is therefore real) as long as it appears in a field of sense. (Gabriel, p.50)

Different fields of sense have different modes of access, and our human senses are simply the mode of access to a field of sense that encompasses the totality of human experience (Gabriel, p.230). In such a field of sense, anything we perceive is real, and anything real can be perceived as such (Gabriel, p.97); such 'human' reality can, therefore, be known as it is.


Knowledge of reality is at the crossroads of ontology and epistemology.

In this essay, I have suggested a definition of 'real knowledge' and argued that it could not be acquired, both a priori and a posteriori, with complete certainty.
The 'real' world may well be a meaningless, shapeless, unorganized distribution of particles without the order we are conferring to it.

As it stands, our notion of reality may simply be too restrictive, rendering it epistemologically inaccessible to us.

We may not be able to know reality as it is, but if we accept the possibility of many realities or fields of sense as suggested by Gabriel, there may be a more 'human reality' to which we have unencumbered access; a reality that we could know intimately, as it is.
Wouldn't that be good enough?


  • Descartes, Guttenplan: Samuel Guttenplan, Jennifer Hornsby, Christopher Janaway, John Schwenkle, From ‘Rene Descartes: Second Meditation’, in Reading Philosophy (Wiley Blackwell, 2021)
  • Locke, Guttenplan: Samuel Guttenplan, Jennifer Hornsby, Christopher Janaway, John Schwenkle, From ‘John Locke: An Essay Concerning Human Understanding’, in Reading Philosophy (Wiley Blackwell, 2021)
  • Blackburn: Simon Blackburn, Think (Oxford University Press, 1999)
  • Henderson, Lea, Spring 2020: Henderson, Leah, "The Problem of Induction", The Stanford Encyclopedia of Philosophy (Spring 2020 Edition), Edward N. Zalta (ed.), URL = https://plato.stanford.edu/archives/spr2020/entries/induction-problem/.
  • Miller, Alexander, Winter 2019: Miller, Alexander, "Realism", The Stanford Encyclopedia of Philosophy (Winter 2019 Edition), Edward N. Zalta (ed.), URL = https://plato.stanford.edu/archives/win2019/entries/realism/.
  • Gabriel: Markus Gabriel, Why the World Does Not Exist (Polity Press, 2015)

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