1. The Problem Does Not Begin with the Brain
Look at a red object.
Physics can describe the electromagnetic radiation entering the eye. We can specify the wavelengths, spectral composition of light, properties of the object’s surface, operation of retinal receptors, signal transmission along the optic nerve, and activity of individual brain regions.
We can continue this description in ever greater depth.
But none of these descriptions contains red itself.
An electromagnetic wave is not red. It has frequency, wavelength, and energy. A neural impulse is not red either. Electrical activity in neurons does not possess redness. A sequence of chemical and electrical processes in the brain is not, in itself, the experience of red that is immediately present to the subject.
This is where the hard problem of consciousness appears:
Why are physical processes accompanied by experience at all?
Not why an organism distinguishes two wavelengths.
Not why a person can say, “This is red.”
Not why information is processed.
Not why one signal causes one response and another causes a different one.
But why there exists what it is like to experience this.
Why red exists.
Why pain exists.
Why the taste of lemon exists.
Why the sensation of warmth exists.
Why sound exists not only as vibrations of air and the processing of signals but as sound that is heard.
Why there is any inner presence of what is happening at all.
2. Why the Problem Is Called Hard
David Chalmers introduced the term hard problem of consciousness in 1995.
He contrasted it with the so-called “easy problems.”
The word “easy” does not mean they are actually easy to solve. Some are extraordinarily complex. The distinction is neither in the amount of computation nor in technological difficulty.
It lies in the type of question.
We can investigate:
- how the brain distinguishes stimuli;
- how attention selects information;
- how memory works;
- how a person recognizes faces;
- how a verbal response is formed;
- which neuronal processes accompany pain;
- which brain areas activate when color is perceived;
- how information is integrated;
- how an organism makes decisions and performs actions.
All these questions concern function, mechanism, structure, or behavior.
The hard problem asks something else:
Why is the performance of these functions experienced at all?
Suppose science has constructed a complete account of how the brain distinguishes red from green.
A signal reaches the retina.
Photoreceptors respond.
The signal is transformed.
Neural networks process it.
The organism classifies the object.
The person says: “Red.”
We can imagine every physical transition being known with perfect precision.
But the question remains:
Where did experienced red itself appear in this account?
That is already another question.
3. Visible Light Does Not Itself Look Like Anything
The phrase “visible light” can easily be misleading.
It sounds as though light exists that already possesses some appearance.
But electromagnetic radiation does not itself “look” like anything.
A wavelength of approximately 650 nanometers does not contain a tiny red color inside it.
It is a physical quantity.
What is red is the experience that arises for a subject under particular perceptual conditions.
This distinction is fundamental:
wavelength ≠ color as experience.
There is a stable connection between them. But connection is not identity.
A physical event can be described from outside:
electromagnetic radiation with a certain spectral composition interacts with a certain system.
Experience exists differently:
I see red.
The former is a description of a process.
The latter is a present experience.
The hard problem is precisely between them.
4. “Red” as a Category and Red as an Experience
Here another extremely important substitution appears.
To the question:
Where does red come from?
one may answer:
Red is a category used by people to denote a certain range of colors.
But this is an answer to an entirely different question.
The category explains classification.
It does not explain the emergence of experience.
We can investigate how different cultures divide color space. We can investigate words denoting shades. We can investigate the boundaries of categories.
But before a person calls something “red,” there is what they see in the first place.
Suppose someone has never heard the word “red.”
The experience does not disappear because of that.
The category organizes experience that already exists.
It does not explain the existence of experience itself.
Therefore the response:
“This is just a category”
does not solve the hard problem.
It jumps from the question of the emergence of experience to the question of its classification.
5. Correlation Is Not an Explanation of Emergence
Suppose a researcher discovers a perfectly precise correspondence:
Whenever a person experiences red, process X always occurs in their brain.
That is an extraordinarily important discovery.
But logically it establishes a relationship:
X is accompanied by the experience of red.
It does not yet answer the question:
Why is X the experience of red?
One can build an ever more precise map of correspondences.
X1 corresponds to red.
X2 corresponds to blue.
X3 corresponds to pain.
X4 corresponds to the taste of coffee.
X5 corresponds to fear.
The result would be an incredibly detailed atlas of consciousness.
But an atlas of correspondences and an explanation of emergence are different things.
We may know:
In brain state X, the subject reports experience Y.
The hard problem asks:
Why does Y exist?
This is why discovering a neural correlate of consciousness is not automatically an explanation of consciousness.
A correlate answers the question “What is experience connected with?”
The hard problem asks “Why does experience arise at all?”
6. “The Brain Builds a Picture of the World”
A very common explanation goes as follows:
The brain receives signals from sense organs and builds an internal picture of the world.
This seems to be an explanation until the next question is asked:
What does “picture” mean?
If it means merely some structure of neural activity, the problem remains the same.
The structure exists.
But why is the structure visible?
Why is there an experienced image?
If the word “picture” is meant literally, another problem appears:
Who looks at this picture?
A hidden observer within the brain is introduced.
The brain constructed an image.
Now someone has to see it.
But then consciousness has quietly been inserted into the explanation as a ready-made premise.
This is the familiar danger of the internal spectator model: an explanation of perception starts to presuppose another perceiver.
Therefore the formulation:
“The brain constructed a picture”
can describe a transformation of information but does not itself explain the emergence of experience.
7. Information Does Not Automatically Solve the Problem Either
Sometimes “information” is used instead of “picture.”
The brain receives information.
Processes information.
Integrates information.
Transmits information.
Stores information.
But the meaning of the word must be monitored very carefully here.
If information refers to a physically distinguishable state of a system, enormous numbers of processes can be described without referring to experience at all.
One signal differs from another.
The system reacts to them differently.
The system’s states change.
This is sufficient for a functional description.
But differences between states do not explain why one of those states is experienced as red.
Otherwise the word “information” imperceptibly starts doing two jobs.
At first it means a difference between physical states.
Then the meaning “consciously experienced information” is already inserted into it.
And consciousness ends up inside the definition that was supposed to explain it.
8. Distinction Is Not Experience
Imagine a device with two sensors.
If sensor one receives signal A, the device writes:
RED.
If it receives signal B:
GREEN.
The device distinguishes two states perfectly.
One can add a neural network.
One can add learning.
One can add context.
One can add memory.
One can add forecasting.
One can add the ability to describe its own internal states.
The functional system will become extraordinarily complex.
But from the description of its functions alone, it still does not follow that experienced red has appeared somewhere.
That is why the hard problem cannot be reduced to the ability to distinguish stimuli.
Distinction is a function.
Experience is how a state exists for a subject.
9. Pain Shows the Distinction Especially Clearly
With pain, this distinction becomes even more evident.
We can describe:
tissue damage;
activation of nociceptors;
signal transmission;
the operation of the spinal cord;
brain activity;
changes in behavior;
withdrawal of the hand;
release of hormones;
formation of memory;
avoidance of the source of damage.
All of this answers the question:
What does the system do when damaged?
But pain contains something else.
It hurts.
It is not merely that a signal has arrived.
Not merely that avoidance behavior occurred.
There is an experienced quality.
We can remove “pain” from a functional description and replace it with a sequence of physical processes.
But the experience itself will not thereby have been explained.
10. Emergence Is Not an Explanation in Itself
Another common answer:
Consciousness is an emergent property of the brain.
This formulation can designate a particular research position.
But the word “emergence” itself explains nothing yet.
Suppose:
many neurons interact;
consciousness emerges with a certain organization of the system.
Fine.
Now the original question arises:
Why is precisely such an interaction accompanied by experience?
If the answer is:
because consciousness is emergent,
the result is:
consciousness arises because it arises with a particular organization of a system.
Naming the relationship has replaced an explanation of its mechanism.
For emergence actually to become an explanation, one must show not only under what conditions a phenomenon arises, but also why experience itself follows from those conditions.
And the hard problem reappears.
11. “It’s an Illusion” Does Not Eliminate the Question Either
There is a position according to which some of our ideas about consciousness are illusory.
But the word “illusion” requires particularly careful examination.
An illusion must itself exist in some way.
If it seems to a subject that they experience red, then at least this “seeming” exists.
If it seems to a subject that pain has a particular quality, then the very emergence of that seeming quality must be explained.
One can reject a particular theory of experience.
One can assert that a subject misinterprets their own states.
One can reject the existence of special metaphysical objects called “qualia.”
But one cannot remove the question itself by simply replacing “experience” with “illusion.”
Because the next question arises:
How does the illusion itself exist?
If the illusion is not experienced at all, it is unclear in what sense it is an illusion.
If it is experienced, the hard problem returns.
12. The Hard Problem Does Not Assert Dualism
It is important not to make the opposite mistake.
The existence of the hard problem does not automatically imply:
consciousness is immaterial.
Nor does it imply:
physicalism is false.
Nor:
a soul exists as a separate substance.
Nor:
science will never be able to explain consciousness in principle.
The hard problem precedes these answers.
It fixes a rupture between two types of description.
On one side:
structure, function, causality, computation, behavior, physical process.
On the other:
experience.
Different philosophical positions subsequently propose different ways of understanding this rupture.
One can assert the identity of the conscious and the physical.
One can introduce additional fundamental properties.
One can regard the formulation of the problem itself as mistaken.
One can reconsider the concept of the physical.
One can reconsider the concept of consciousness.
But first we must not lose the question itself.
13. “The Brain Creates Consciousness” Explains Nothing Yet
Sometimes an explanation takes this form:
The brain creates consciousness.
This may be a hypothesis concerning the dependence of consciousness on the brain.
But the verb “creates” conceals the entire problem inside itself.
How does it create it?
What sequence of events turns a physical state into experience?
Why does a particular organization of matter possess an inner side?
Why does a subject arise at all for whom something is present?
If the mechanism is unknown, the word “creates” names a relation without explaining it.
The same applies to:
the brain generates consciousness;
consciousness arises from neural activity;
consciousness is a product of the brain.
Each phrase may express a particular position.
But each leaves open the word doing all the work:
arises.
How does it arise?
That is the hard problem.
14. The Main Trap: Explaining Function and Declaring Experience Explained
The hard problem constantly disappears from conversation in the same way.
Someone asks:
Why does the experience of color exist?
The response is:
Because the visual system distinguishes wavelengths.
But that was not the question.
Someone asks:
Why is pain felt?
The response is:
Pain allows an organism to avoid injury.
But this is an explanation of the function of pain, not of the existence of painfulness.
Someone asks:
Why does subjective experience exist at all?
The response is:
Because the brain needs to build a model of its environment.
This may explain the usefulness of a particular mechanism.
But the usefulness of a mechanism does not explain why the operation of the mechanism feels like anything.
A systematic transition occurs:
experience → function → explanation of function → declaration that experience has been explained.
This is precisely the transition that must constantly be noticed.
15. Evolutionary Usefulness Also Answers Another Question
We can ask:
What was consciousness needed for in evolution?
But that is already a teleologically formulated question, which must be translated carefully:
Which properties of an organism associated with consciousness could have influenced its survival and reproduction?
Even if a complete answer to this question is obtained, the hard problem remains.
Suppose the ability to distinguish colors gave an organism an enormous advantage.
This explains the preservation of the ability to distinguish particular stimuli.
But why is distinction accompanied by actually seeing color?
Functionally, we can imagine a system:
signal A → response A;
signal B → response B.
This is enough to explain behavior.
Where does experience arise within this chain?
An evolutionary explanation of a function and an explanation of the existence of phenomenal experience are different explanatory tasks.
16. The Shortest Way to See the Problem
We can remove almost all of neurobiology.
Suppose two brain states exist:
A and B.
A corresponds to an experience of red.
B corresponds to an experience of blue.
A physical description can establish every difference between A and B.
The number of activated neurons.
Connections.
Impulse frequencies.
Chemical states.
Electromagnetic activity.
Causal history.
The organism’s subsequent behavior.
Now the question:
Why does A look red, while B looks blue?
We can answer:
because A is the state corresponding to red.
But this merely repeats the original correspondence.
We can answer:
because that is how the brain is built.
But the hard problem asks precisely how such a structure becomes experience.
We can answer:
because the system interprets A as red.
Then the question arises:
What does “interprets” mean?
If it is another physical operation, we must again explain why it is accompanied by experience.
If “interpretation” already means conscious experience, consciousness has been hidden within the term used to explain it.
17. We Can Explain Behavior Perfectly and Still Not Explain Consciousness
Here lies the radical character of the hard problem.
Imagine an entirely complete model of a human being.
The model predicts every movement.
Every word.
Every decision.
Every change in pulse.
Every shift of attention.
Every memory.
Every phrase:
“I’m in pain.”
Even such a model may still leave a separate question:
Why does someone exist for whom it hurts?
Not in the sense of looking for a little person inside the head.
But in the sense of the existence of the very fact of experience.
Functional completeness of description does not yet demonstrate the identity of functional description and experience.
If such an identity exists, it still needs to be explained.
18. This Is Where the Subject Appears
The hard problem of consciousness appears especially sharply when a description is built entirely from the third-person perspective.
From outside, we can observe:
the organism;
the brain;
neurons;
impulses;
movements;
words;
reactions.
But experience does not exist for the subject as an external observation.
The subject does not conclude:
presumably, there is currently a state of pain in my nervous system.
It hurts.
The subject does not calculate the presence of red from instrument readings.
They see red.
Experience is given immediately.
And here two perspectives collide.
The third-person perspective:
physical state X occurred.
The first-person perspective:
I experience Y.
The hard problem asks how these two sides are connected.
19. Why the First Person Cannot Simply Be Discarded
One can attempt to say:
Science works only with objectively observable phenomena, so subjective experience may be excluded from the description.
But then the problem is not solved.
The subject of investigation is simply removed.
If consciousness must be explained, we cannot define it so that the very thing for which the question was raised disappears from the definition.
We can construct an excellent science of behavior.
We can construct an excellent neurophysiology.
We can construct an excellent theory of information processing.
But consciousness became a problem precisely because, beyond behavior, neurophysiology, and information processing, experience exists.
If it is removed, the resulting theory is about something else.
20. The Question Is Therefore Extremely Simple
The hard problem can be formulated without specialized terminology.
Why is anything felt at all?
Why does light not merely start a physical chain of reactions, but become visible?
Why does damage not merely cause defensive behavior, but become pain?
Why do air vibrations not merely get transformed by the nervous system, but become sound?
Why do chemicals not merely trigger receptor reactions, but become taste?
Why does a physical system not merely change state, but have an inner experiential side?
And finally:
Why is the world present at all for the subject?
21. What Exactly Remains Unexplained Here
The hard problem of consciousness is not a lack of a detailed map of the brain.
It does not automatically disappear as the map’s resolution increases.
We can know more and more about what happens together with experience.
But that does not answer why what happens is experience.
Here is the boundary:
the mechanism of distinction is not the experience of a distinction;
a neural correlate of color is not redness;
a description of pain is not painfulness;
information is not consciously experienced information;
a reaction is not a sensation;
behavior is not subjective experience.
The connection between them may be extraordinarily strict.
But a strict connection alone does not explain why one side possesses the other.
22. The Hard Problem as a Test of Explanations
The hard problem may therefore be used not only as a philosophical question, but also as an instrument for testing explanations.
Whenever the assertion appears:
“We have explained consciousness,”
we can ask one question:
Did you explain the emergence of experience, or only a mechanism, function, correlation, and behavior?
If an explanation ends with:
the system distinguishes;
the system processes;
the system integrates;
the system represents;
the system encodes;
the system classifies;
the system reports;
we must check whether the next transition was simply left undescribed:
why is all of this experienced as something?
That tiny transition contains the whole problem.
Linguistically it is so small that it can be hidden in a single verb:
arises.
Neural activity occurs.
And experience arises.
But between the first sentence and the second lies the entire hard problem of consciousness.
23. Condensed Formula
The hard problem of consciousness does not ask:
How does the brain process information?
It asks:
Why does information processing have an experiential side at all?
It does not ask:
How does a person distinguish red and blue?
It asks:
Why is this distinction accompanied by red and blue as experiences?
It does not ask:
Which neurons are activated during pain?
It asks:
Why does this activity hurt?
It does not ask:
How does an organism build a model of its environment?
It asks:
Why does the world the subject sees, hears, feels, and experiences exist at all?
And as long as an answer substitutes a mechanism for experience, function for existence, correlation for the cause of emergence, or category for the phenomenon itself, the hard problem does not disappear.
It is merely closed off with words.
