By the “hard problem”, I’m referring to the exposition by David Chalmers.

He phrased the hard problem as “why objective, mechanical processing can give rise to subjective experiences.” I find it difficult to think of this as hard.

Imagine the following. People are really pre-programmed computers coupled with various sensory inputs. The computer has a “task manager” that monitors and controls all the software being ran: the visual recognition software, the math arithmetic software, the emotional perception and expression software, etc. Then, it seems like this task manager is “conscious”. Only the task manager itself is aware of the programs ran, and others don’t see the program status. This, the awareness is “subjective”.

How David Chalmers talks about the problem of consciousness make it seem I must be missing something in my description?

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    What behavior of other people or computers seems like is irrelevant to the hard problem, reproducing human behavior with AI is an "easy" problem. The reason we believe other people are conscious is the analogy with ourselves, and in our own case we experience "what it is like" first hand. The hard part is to explain why physical processes in computers or our brains should be accompanied by such first person feels at all when zombies lacking them could follow the same physical laws and manifest the same outward behavior without them. – Conifold Nov 18 '20 at 15:38
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    That is not what it means at all. Private content can be and is easily explained by neuroscience models. People talking about the hard problem of consciousness talk about something else, the "experienced quality" nature of first person feels, which seems orthogonal to any third person descriptions of what they might accompany. Publicity/privacy is just one such description, that they happen to be private is just a side effect. – Conifold Nov 18 '20 at 23:25
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    @AmeetSharma Yes. I think we have arrived at a conclusion in this discussion. The "hard" problem of consciousness is essentially equivalent to "we think human experience cannot be explained by mechanical processes" -- which again, is an assumption, even though a very intuitive assumption to all of us (it "feels" like the right assumption). Whether this problem is "hard" depends on the subsequent progress in cognitive sciences. – J Li Nov 19 '20 at 3:28
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    @AmeetSharma I agree, and I think we have reached a consensus on this topic. Thanks for the discussion! – J Li Nov 19 '20 at 4:28
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    Feels may well be perfectly correlated with neurons firing, but that would do nothing for the hard problem. It is not about relations and correlations. Their arguments is simple: scientific explanation is based on modeling, models are matched to third person descriptions, while feels can be correlated to something so describable they themselves are not, therefore science can not explain them as such. That's why the problem is "hard". It would require inventing some new mode of explanation, either to bridge the feel/description gap or to explicate why no explanation is called for. – Conifold Nov 19 '20 at 5:44

What matters is not the fact that the experience is subjective per se, what matters is that there is no way to share the quality or quale of that subjective experience with anybody else.

If you see a shade of red, how do you know how others experience it? Some people have different chemoreceptors for red and will experience it as a different shade. Others are red-green colourblind but cannot tell the rest of us whether they experience all reds as greens or all greens as reds or something else. Some octopuses are sentient and have colour vision; their brains evolved entirely separately from ours (last common ancestor was probably a flatworm), so how do they experience the redness of say a sea anemone?

Other animals have other senses - electric, magnetic, etc. which we do not. Some birds sense geomagnetic fields with their eyes, some birds are sentient. But we homo sapiens have no processing pathways for magnetic senses and so can never know, not even in principle, the subjective quale of looking at a magnetic field.

All the encephalography, signal reconstruction and computational simulation or senteint AI in the world cannot enable any quale of redness to be identified, recorded and communicated.

Consequently no law of physics, nothing founded on the laws of physics, nothing reducible to the laws of physics, can describe qualia (the plural of quale). There is no way you can objectively capture subjective experiential qualities, in order to compare them and see if they are the same or not. They are simply not open to objective science in the way that their neural correlates are.

That is what is hard about the hard problem.

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    This goes to far in the direction of impossible: "Consequently no law of physics, nothing founded on the laws of physics, nothing reducible to the laws of physics, can describe qualia (the plural of quale). They are simply not open to objective science." Perhaps, perhaps not. We don't know whether we will ever understand "qualia". Of course you can fight over definitions but what if someday we manage to really reproduce your vision of a painting in someone else's mind. (Through for example a complete understanding of neurons and their states and how to read/write them to a specific state.) – Kvothe Nov 18 '20 at 18:10
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    @JLi The key point is that the perceptual nature of the qualia is not open to confirmation. You and Mary have not the slightest idea how the subjective qualities of your experiences compare. For a scientific rationalist (often a materialist), that makes it a problem - and, worse, a hard problem with no apparent solution even in principle. Of course, if you are not an atheistic scientific rationalist then there is no problem, hard or soft. – Guy Inchbald Nov 18 '20 at 19:38
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    "But we homo sapiens can never know, not even in principle, the subjective quale of looking at a magnetic field." Are you sure about that? – Joshua Nov 18 '20 at 20:52
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    @Joshua Yes I am sure. The human body does not posses the necessary sensory pathways. Any human-like person capable of doing so would no longer be homo sapiens but some GM mutant. (bad jokes about birdbrains strictly forbidden!) – Guy Inchbald Nov 19 '20 at 9:22
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    Enough has been said. Those who choose not to buy the hard problem are at liberty to disagree, but I have described it as best I can. – Guy Inchbald Nov 19 '20 at 11:21

Q: … He phrased the hard problem as “why objective, mechanical processing can give rise to subjective experiences.” I find it difficult to think of this as hard. …

... Then, it seems like this task manager is “conscious”. Only the task manager itself is aware of the programs ran, and others don’t see the program status. This, the awareness is “subjective”.

How David Chalmers talks about the problem of consciousness make it seem I must be missing something in my description?

A: You seem to miss the most important word “experiences”.

What is hard about the hard problem of consciousness is why there is subjective experience occurring with consciousness (1-5) and not why awareness or subjective awareness occurs with consciousness (as you seem to understand). Chalmers himself says these:

The hard problem of consciousness is the problem of experience. Humans beings have subjective experience: … There is something it is like to see a vivid green, to feel a sharp pain, to visualize the Eiffel tower, to feel a deep regret, and to think that one is late. Each of these states has a phenomenal character, with phenomenal properties (or qualia) characterizing what it is like to be in the state.

There is no question that experience is closely associated with physical processes in systems such as brains. It seems that physical processes give rise to experience, at least in the sense that producing a physical system (such as a brain) with the right physical properties inevitably yields corresponding states of experience. But how and why do physical processes give rise to experience? Why do not these processes take place "in the dark," without any accompanying states of experience? This is the central mystery of consciousness.” (1)


“For any physical process we specify there will be an unanswered question: Why should this process give rise to experience? Given any such process, it is conceptually coherent that it could be instantiated in the absence of experience.” (2)

For example, when we see a house, listen to a song, or smell a rose, in addition to the awareness (similar to the computer awareness) of those things, we have subjective experiences of what it is like to see the house, to hear a song, and to smell a rose occurring in our mind (see figure below) (6). The hard problem is “Why do these subjective experiences occur in our mind – why do we not just process these kinds of information in the dark without subjective experiences occurring as computers do in their information processing?”

Subjective experiences

You are right that computers can be subjectively aware of the image of the house, the sound of the song, and the smell of the rose, but so can we. Thus, subjective awareness is not the issue that makes the hard problem of consciousness hard and does not differentiate us from computers. On the contrary, at present, there is no evidence that computers have subjective experiences as we do. Therefore, it is the subjective experiences that make the hard problem of consciousness hard and differentiate us from computers.

This is in contrast to the easy problems of consciousness:

“The easy problems of consciousness include those of explaining the following phenomena: the ability to discriminate, categorize, and react to environmental stimuli; the integration of information by a cognitive system; the reportability of mental states; the ability of a system to access its own internal states; the focus of attention; …

Although we do not yet have anything close to a complete explanation of these phenomena, we have a clear idea of how we might go about explaining them. This is why I call these problems the easy problems. Of course, "easy" is a relative term. Getting the details right will probably take a century or two of difficult empirical work. Still, there is every reason to believe that the methods of cognitive science and neuroscience will succeed.” (2)

And at present, a lot of advances have been made regarding the easy problem of consciousness. Although we still do not know all the details about it, we now have a good general idea of what the neural correlate of consciousness (7-9) is like. The complete knowledge of neural correlate of consciousness will completely solve the easy problem of consciousness.


  1. Chalmers DJ. Consciousness and its place in nature. In: Chalmers DJ, editor. Philosophy of mind: Classical and contemporary readings. Oxford: Oxford University Press; 2002. ISBN-13: 978-0195145816 ISBN-10: 019514581X.

  2. Chalmers DJ. Facing up to the problem of consciousness. J Conscious Stud. 1995;2(3):200-219.

  3. Chalmers DJ. Moving forward on the problem of consciousness. J Conscious Stud. 1997;4(1):3-46.

  4. Weisberg J. The hard problem of consciousness. The Internet Encyclopedia of Philosophy.

  5. Van Gulick R. Consciousness. In: Zalta EN, editor. The Stanford Encyclopedia of Philosophy.

  6. Ukachoke C. The Basic Theory of the Mind. 1st ed. Bangkok, Thailand; Charansanitwong Printing Co. 2018.

  7. Chalmers DJ. What is a neural correlate of consciousness? In: Metzinger T, editor. Neural Correlates of Consciousness: Empirical and Conceptual Questions. MIT Press, Cambridge, MA. 2000

  8. Koch C, Massimini M, Boly M, Tononi G. Neural correlates of consciousness: Progress and problems. Nature Reviews Neuroscience. 2016;17: 307-321. https://puredhamma.net/wp-content/uploads/Neural-correlates-of-consciousness-Koch-et-al-2016.pdf

  9. Tononi G, Koch C. The neural correlates of consciousness: An update. Annals of the New York Academy of Sciences. 2008;1124:239-61. 10.1196/annals.1440.004. https://authors.library.caltech.edu/40650/1/Tononi-Koch-08.pdf

  • Thank you so much. My issue with the “hard problem” is about our understanding of “experience”. The typical neuroscience perspective is that “experience” is no more than patterns of neurons firing, and “experience” is simply an intuitive way human brains perceive such patterns. Thus, it seems that the “hard” problem boils down to us saying “I find it hard to imagine that my experience is just neurons firing”. To be a little dramatic (purely for exposition), this objection isn’t that different from “I cannot imagine humans evolving from animals”, and thus we have a “hard problem of evolution”. – J Li Nov 18 '20 at 17:08
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    I agree with you that the answer must lie in it is somehow an effect of neurons firing. But you are completely wrong if you think that this "somehow" is currently understood. If you would start simulating a bunch of neurons from scratch not knowing our human experience you would definitely not have predicted that those neurons would develop consciousness. – Kvothe Nov 18 '20 at 18:20
  • @JLi what exactly do you mean by "is" in "I find it hard to imagine that my experience is just neurons firing"? Therein perhaps lies the difficulty. Firing neurons "are" experience only in a similar sense to music "being" soundwaves or notes, or soccer "being" 22 people running around and kicking a ball. – henning -- reinstate Monica Nov 18 '20 at 20:43
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    @Yuri, I don't see how that goes against what I was saying. First off all this is far of from AlphaGo starting outputting thoughts on how he was perceiving things and outputting awareness of himself as an entity and his thought process. Secondly even if we did we would not yet understand (although we would probably get closer). An important step would be I think when you can from a microscopic model predict that the neurons would become self-aware/conscious. So not just know it has to happen because you saw it happen but actually be able to predict it from the building blocks of neurons. – Kvothe Nov 19 '20 at 10:22

The difficulty is in explaining consciousness in terms of the kind of things that are in the physical world. No one has a clue how to that.

Many people believe we will one day explain mental contents in physical terms. For example, we might one day be able to explain human deductive logic in terms of the physical characteristics of neurons like we can explain the logic of a computer in terms of its hardware. We might also one day be able to predict the behaviour of a human being from a brain scan like we predict the weather by looking at the Earth's atmosphere. Yet, nobody has a clue as to how the quality of our subjective experience could possibly ever be explained in terms of subatomic particles, quantum events or some such. We don't even know where we would have to begin.

Then again, I fail to see what would be the use of doing that. We don't seem to need to explain consciousness.

This isn't the only problem seemingly impossible to solve either. Any fundamental constituant of reality could not possibly be explained in terms of the physical world. Maybe subjective experience is just such a constituant.

Funnily, consciousness would then be the only such fundamental constituant of reality we actually know and will ever know. So not only do we probably not need to explain consciousness, but we seem to know all there is to know about it.

It is also likely that our qualia are the only things we will ever really know of the real world. So the real problem is not to explain our qualia and subjective experience, but to make sure our beliefs about the physical world are reliable enough for us to survive in it and prosper.

  • ur philosophy is more similar to Leibniz's idealistic Monism than Descartes' dualism, just curious why instead u put Descartes pic as ur avatar?? – Double Knot Mar 10 at 18:04
  • @DoubleKnot 1. There is nothing idealistic in my position, on the contrary: "We don't seem to need to explain consciousness" - 2. Descartes because of the Cogito, which explains why we cannot explain consciousness. – Speakpigeon Apr 8 at 9:33

The Question

David Chalmers did not express it clearly in that quote (which is a loaded question, btw). What he meant to ask is "What did Mary learn, when she saw the red color for the first time?"

As the story goes, Mary is a brilliant scientist and a leading expert in everything color -- what they are (bands in EM spectrum), how they're sensed by the eyes, and how they reconstructed by the brain. Amazingly she accomplished all that w/o actually seeing a color. She is not colorblind, but she has been living in a black and white environment. Her lab, home, furniture, screens all monochrome, the shades of gray... until one day when she got out and saw red leaves on the trees (it was a beautiful day in the fall).

And that was Chalmers's question -- what Mary had learned in that moment? She already knew everything there is to know about colors. Yet, seeing red was not just a novel experience, it enriched her life in the most profound way -- which would not be possible unless she had learned something just from seeing the color... but what exactly did she learn? <== and that, again, is the so-called "hard problem".

A (very short) Answer

Now if you think about it, the "hard problem" question is essentially about the nature of fundamental concepts -- also platonic forms, also John Locke's "simple ideas", also Immanuel Kant's "intuitions", etc... like your concept of a "chair", or a "jump", or, indeed, of what counts as "red".

It is a knowledge of sorts -- like, you know what a chair is, don't you? But try and give a precise definition of what is -- and what isn't! -- a chair in rational terms, and you will soon find yourself grasping for words and only becoming more frustrated, realizing... wait, you don't know what a freaking chair is!?..

Well, strictly speaking, you don't, for it is not a rational knowledge.1 What you do have, instead, is a pretty good idea of what constitutes a chair. And, unlike knowledge, ideas/concepts are not products of your rational Self. They are created by your neural network AI, commonly referred to as your "subconsciousness".2

In fact, "getting ideas" of things is what neutral networks do as their way of processing experiences. Being, at its core, an image recognition system, a neural net treats everything as a picture,3 looking for similar patterns and anti-patterns in different depictions of the same class/type of things.

A concept of a chair, therefore, is but a collection of numerous patterns found in things classified as chairs by some trusted authority. Plus the anti-patterns, their presence strongly suggesting the thing is not a chair.

And that's your qualia, hopelessly subjective, as it should be, a sea of simple concepts. The rational Self then uses them as lego pieces to assemble three-dimensional mental models, each simulating a certain aspect of reality. If simulation correctly describes the real thing -- if it's true -- then it is promoted to the rank of knowledge. The individual models, in turn, become pieces of the ultimate jigsaw puzzle, the Big Picture -- a complete simulation of the world. Modeling ourselves, as a part of it, makes us self-aware and, thus, capable of conscious choice.

And... that's all there is to it. The real hard problem is not the consciousness -- it's us, creating obstacles upon obstacles, making something that everyone should have pretty much out of reach.

1 We can call it "irrational knowledge", but I'm afraid that would bread a lot of confusion.

2 In some way, it functions very similarly to a Flight Computer, first adopted in the modern fighter jets (F-16 was the first to take full advantage). At the time, they wanted to make them extremely agile, but that would also make them aerodynamically unstable, impossible for a human to control. Enter Flight Computer. Capable of making minute adjustments of individual control surfaces every split second, and could fly a brick with winglets (and so it did with Space Shuttle). The human pilot is still there, of course, but they can only access FC. The good FC then makes the pilot feel like they are in control, by doing its best to interpret and accommodate the pilot's intentions. Or not, if the FC knows better, as it happened with US Airways Flight 1549 (the "Miracle on the Hudson"), when, for the last minute of the fight, the FC diligently ignored the pilot's trying to lift the plane nose up, which would have ended in a stall like this...

3 the actual meaning of "being superficial"

  • Thank you Yuri. From a neuroscience perspective, it seems that the answer is clear? When Mary lives in a colorless environment, she learned such knowledge rationally (mostly in her frontal cortex). When she saw the color for the first time, it is a different set of neurons firing. Thus, these two are very different sets of neurons firing. For simplicity, we call the former “knowledge” and the latter “experience”. – J Li Nov 18 '20 at 17:13
  • That is correct! Tho as far as the answer goes, it barely scratches the surface. The most substantial part is the "two minds" concept -- humans having two independent centers of cognition: 1) the rational (tho seldom conscious) Self, and 2) the irritational (subconscious) neural net. The two are nothing alike -- both in terms of what they do and how they do it. Even their availability differ -- while the irrational mind is a given, the rational becoming at all operational is very much an option (achieving its nominal performance in next to impossible, grace of, umm... "civilization"). – Yuri Alexandrovich Nov 18 '20 at 21:57
  • Isn't it obvious that she's learnt how her organism reacts to the color? There's simple mathematical argument that shows that sometimes you cannot predict things, no matter how much you know. – Dmitri Urbanowicz Nov 19 '20 at 10:01
  • @Dmitri > "Isn't it obvious that she's learnt how her organism reacts to the color?" -- she didn't "react to the color", she reacted to seeing it. She reacted because she learned something the moment she saw the first time. – Yuri Alexandrovich Nov 19 '20 at 22:10
  • @YuriAlexandrovich I didn’t say “she reacted”. I said her body did, which is in no way contradictory with saying that her self reacted to her seeing. My point is that you can invoke the same argument about unexpected experience even if “Mary” is just a Turing Machine. – Dmitri Urbanowicz Nov 20 '20 at 4:50

Not only do we have something we call experiences, we are also aware of having experiences and we can reflect about them, have feelings about them etc.

This meta-stuff is not (yet?) within the realm of what computers can do or are expected to do. So it's a hard problem both philosophically and scientifically.

  • The real hard problem is not about the consciousness itsef. It's about having it in the first place, which most of us don't. We are supposed to be our conscious, rational Selves, but most of us are forced to commit a virtual suicide early in childhood. Alone and betrayed, their Selves effectively give up on thinking, on making conscious choices, on their agency. Once their neural net AI, their subconsciousness takes over their thought process ('cause someone has to drive!), their Selves becomes their helpless, nagging Ego -- sometimes observing.... – Yuri Alexandrovich Nov 19 '20 at 23:19
  • .... from backseat, or fast asleep in there, leaving their neural net AI chatbot/autopilot to try and make it "look* like they are still conscious, still awake at the wheel... – Yuri Alexandrovich Nov 19 '20 at 23:20
  • .... i don't know what else I can do, to wake them up – Yuri Alexandrovich Nov 19 '20 at 23:21

When you are talking about a green apple, your experience is that green apple. When you are talking about neurons switched on in your brain while one is talking about the apple, your experience are those neuron cells. You see - objects of your consciousness are different.

You say, "but they correspond perfectly, the apple qualities and the cell's parameters", and you describe how in details. But then the object is the correspondence, yet a third and another object.

If you hope to substitute the apple perception by the equivalent neurochemical status you will have to train yourself to visualize the latter whenever somebody says "apple". There will be substitution of objects, and that is all.

Moreover, the experience of an object is immersed in ones current project (expectations, wishes, mood etc). My impression of the green apple is very specific if my tooth is on sore. Likewise, your attempt to link my this experience with brain cells is unique in another way, say, because you are preparing your thesis and are motivated by the prospect. But both "contexts", yours and mine, are not clearly apprehended most of the time and so, scientifically speaking, are hard to control for.

You might protest on the object whirl, "I believe apple and neurons reside in the world even when I don't think about them". Your right. Still, when you are thinking about their correspondence, you are keeping them apart. To relate or compare two things (even as equivalent) means to deny their identity. So, your effort to map the green apple image onto the neuronal firing field strengthens and sharpens the distinction between the counterparts. Thus a physical explanation of an experience is self-defeating.

You may resist, "I'm talking about a correspondence between the intrapsychic image and the brain, not about the apple out there and the brain". Then you are a mystic. For, there is no anything inside consciousness. Consciousness is void - it is just activity about things (material or imaginary) of the outer world (yes, imagination is an outer experience). By putting a spook proxy of the apple in place of the apple and drawing links between neurons and the proxy you are playing a forgery (called modelling) because you can move the spooky instance as close to the brain as possible while (groundedlessly) claiming it "represents the experience/qualia".

Those were remarks con scientific reductionists. Now about the hard problem of consciousness itself. Wikipedia describes it as follows: "The hard problem ... is the problem of explaining why ... we have ... phenomenal experiences".

Since I tend to be a phenomenologist, that is not a problem for me: everything in the world are just phenomena (which exist as experienced aka apparent) and there is no anything besides phenomena.

So I would reformulate the hard problem by shifting the accent: "The hard problem ... is the problem of explaining why ... we have ... phenomenal experiences (rather than we are they)".

To have something is alias to not be it, or (put differently) to be it by the mode of a lack or via a clearance. That is the hard problem which science-based reductions cannot help, I suspect.

  • My only argument against phenomenology is it seems lacking guiding metaphysical principle since as u mentioned it denies either material or rational mind ideal as real ontological substance (real existence ontologically) which reflect through our sense organs become our experienced phenomena as materialism and idealism trying to leverage. So ur phenomenology is basically back to a layman just using one phenomenon to explain another phenomenon totally within this perceived world... I'd like to see if u have anything to say about this lack of ontological substance issue of phenomenology? – Double Knot Mar 10 at 18:29
  • I have nothing to add because you said it yourself and accurately. Yes, phenomenology sees no need in matter or in spirit (idea). We live in an "layman" (your word; immediate or unprejudiced, my word) world where entities are just serials of phenomena replacing each other. "Let's go back to things themselves" as they appear, is the motto. The kernel is in the obvious, not under it. – ttnphns Mar 10 at 19:31

Referring to your computer example I see this as the difference between a 1960 electronic system and modern computer. In the 60s switch A turned on light A. Now there are many layers and when you press the button in your app there is far more happening before the light comes on.

The easy problem is the hardware, the physical parts of the brain, how an event triggers a sequence of neurons to fire and generate a response. The hard problem is understanding the high level programs that are running. i.e. the sequences, timings, patterns and feedback loops running in that system.

Imagine trying to work out what specific action a user is taking on their smart phone by only looking at a fuzzy memory dump, then reverse engineer a web browser from that information.

  • martin -- you have not understood the hard problem, which has nothing to do with the complexity of calculation algorithms. Our higher level programs are no more or less conscious than our simple ones. – Dcleve Feb 25 at 23:36

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