Epiphenomenalism holds that conscious experience is an ineffectual by-product of brain activities. Eliminationists go further and add that this by-product is an illusion. I was wondering whether anyone in the debate has noticed the glaring epistemological absurdity of describing the basis of all our experience to be an illusion.

So let's see how we normally understand the notion of illusion. In routine cases, illusion is defined as a perception or thought that doesn't correspond to what's believed to be reality. I may hallucinate a phoenix but that would be an illusion for it doesn't correspond to anything in the outer world. I may believe Titans exist, but that's an illusion in that it's a false belief.

In these cases, I have a particular conscious mental state that I may or may not verify as illusion depending on whether or not it corresponds to something in the outer world. So illusion by normal account refers to truth value or correspondence of mental states. Therefore it's an epistemological category. And since there are possibility of true statements, I usually have a way of checking the correspondence/truth value of an experience/belief, and the verification usually involves further using my mind, i.e. using other mental states to determine the correspondence of a particular mental state in question.

However, it seems to be an entirely different thing to claim that rather than a particular mental state, my consciousness itself, that is the background and condition of all my mental states, is an illusion! It's hard not to see how this doctrine is glaringly contradictory for if my consciousness is an illusion how can anything I know and say be not? Under this absurdity, the statement "consciousness is an illusion" itself would be an illusion and therefore false!

This is because under illusionism/emilinationist, the very ground for verification is removed because like I said verification always involves relying on certain conscious mental state(s) to check the truth value/correspondence of some other conscious mental state(s). But if I claim that consciousness is an illusion, it extends to all my mental states. Therefore I lose any basis for checking whether anything else is true or not including this very doctrine. In other words eliminationism/illusionism amounts to epistemic suicide!

So what makes some intelligent philosophers of mind out there to propound such an absurdity in all seriousness?!

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    Indeed eliminativists such as Churchland would agree eliminative claim 'consciousness is an illusion' itself is an illusion, anyway it's just a claim not something displayed naturally in the sky out there. And re your "if I claim that consciousness is an illusion, it extends to all my mental states. Therefore I lose any basis for checking whether anything else is true or not including this very doctrine", it may need be more cautious here and not rush to such an extreme conclusion since one's illusion is not arbitrary but naturally selected and useful to the persistence of the said being... Sep 18, 2023 at 6:17
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    This was already addressed in your previous question. It was noticed by all sides of the debate, the "illusion" is not meant as normally understood, and as understood, although counterintuitive and far fetched, it does not amount to an absurdity. If we are mistaken about existence of mental states and consciousness we are all the more mistaken about the process of verification and the actual basis for it, which is something else (physical, presumably). It is extraordinary, but not contradictory. So what is new here?
    – Conifold
    Sep 18, 2023 at 6:35
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    If you already decided they are "absurd" regardless why ask the question, let alone twice? If the interest is genuine reading them is more effective than snippets here anyway. The implications are heavy, but far from everything, anything and suicide. We have perception, which is known to be mistaken, but not on everything and anything, and we have physical means of verification that correct it. That our brain function compels mistaken self-representations would not imply that its other representations are wholly mistaken, nor will it preclude means of verification that bypass them.
    – Conifold
    Sep 18, 2023 at 8:01
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    Hic sunt dracones Sep 18, 2023 at 8:25
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    Didn't Descartes deal with that in 'I think, therefore I am'? Sep 18, 2023 at 22:08

11 Answers 11


This is simply a corollary to what a few others have stated but felt like giving an empirical example to bolster their claims. Note: by no means am I an eliminitivist, I’m firmly a phenomenologist.

Blindsight studies involve individuals with fully functional eyes but their visual cortex is badly damaged, such that they report not having visual experiences. Nonetheless, they can “guess” with over 80% accuracy what is presented to their eyes (the more emotional the content, the more accurate they get). Interestingly, the doxastic quality of belief is also absent: blindsight patients genuinely believe they are making guesses, and not expressing perceived facts (that is, no introspective access to the visual data whatsoever).

This study observes that blindsight involves "more primitive" neural pathways into the amygdala (that is, subcortical processing). This is why emotional content related to fear or anger increase accuracy, since that part of the brain is geared for that kind of stimuli. This shows that consciousness is not involved, and no special faculty or sense modality is involved: the eyes receive visual data, and is processed unconsciously along subcortical routes.

This indicates that our epistemic powers can function independently of phenomenal consciousness. So, while I strongly disagree with eliminativism, the OP does not present a sufficiently strong argument against it here.

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    A link to these studies would be nice, bolstering a good point.
    – Philip Klöcking
    Sep 18, 2023 at 16:58
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    @PhilipKlöcking Also added a specific study regarding the 80% claim. Thanks for the suggestion!
    – Hokon
    Sep 18, 2023 at 17:15
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    That's an interesting phenomenon but in your analysis you seem to be confusing consciousness with phenomenal (perceptual) consciousness. My argument was very straightforward. Consciousness (in its most broad sense) is the foundation of everything we know, so it can't be consistently described as illusion. And I clearly distinguished in the OP consciousness from particular mental states such as perceptions or beliefs. The significance of blindsight is that there are more mysterious faculties/senses/potentials in our consciousness than those we are normally aware of.
    – infatuated
    Sep 19, 2023 at 14:19
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    @infatuated I do agree my example doesn’t prove EM, the fact that we can compare unconscious perception with conscious says a lot. What it shows though is we can have knowledge without consciousness being integral to that process (so the critique has to shift). Thanks for checking out my answer!
    – Hokon
    Sep 20, 2023 at 5:55
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    +1 for some absolutely fascinating science to go with the argument. Sep 20, 2023 at 10:50

Ok, so you spotted the (glaring indeed) logical contradiction at the heart of eliminative materialism. Good for you. In my experience, it sounds simple and obvious enough once you understood the idea, but many people just cannot understand it.

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    You should take your own advice: "You are welcome to use your own definitions but beware of imposing them on others". When trying to reason against a particular philosophy, it's best to use the definition proponents actually use (as pointed out in 2 answers to your question), rather than arguing against your own convenient definition. Half your quotes are just people trying to play "gotcha".
    – NotThatGuy
    Sep 18, 2023 at 8:44
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    @infatuated "the most stupid idea to plague learned men in history of thought!" I agree. There have been many such stupid ideas to pick from, but this might be the worst. Thankfully it's slowly sinking in the collective psyche that reason cannot undermine reason, experience cannot undermine experience, ideas cannot deny the possibility of ideas, etc.
    – Olivier5
    Sep 18, 2023 at 9:10
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    @Olivier5 Do you understand that "exist" can have different definitions, not all of which would make "ideas don't exist" or "ideas are illusionary" fall into the liar's paradox? Also, why are we phrasing statements as loaded rhetorical questions? Do you understand that this is condescending and not constructive?
    – NotThatGuy
    Sep 18, 2023 at 11:40
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    @NotThatGuy Okay. So what sort of existence do ideas have in your own ontology?
    – Olivier5
    Sep 18, 2023 at 12:11
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    @Olivier5 I don't prescribe to eliminative materialism, but under that, some maintain that consciousness (and thus ideas) is a consequence of brain function, and/or that our understanding of mental states are flawed and don't correspond to the actual workings of our cognitive system. Neither of these entail the fundamental non-existence of what we experience as ideas.
    – NotThatGuy
    Sep 18, 2023 at 14:58

Our means of trying to establish whether something is true (logic, analysis, experimentation, observation) are not reliant on consciousness not being an illusion.

Even if all our methods for establishing whether something is true is illusionary, these methods still produce consistent and reliable results for what we observe.

This is still true even if consciousness is not something we can consciously control (i.e. if we just feel like we have control). That would mean that we don't control how we perform the methods, but the validity of those methods is independent of this. Compare this to a computer, which can do some calculations and reach an answer (and can even have some steps on top of that to validate the calculation and/or answer). In many cases we would consider the calculation to be valid, even though it's commonly accepted that a computer has no consciousness. If we were to somehow attach a consciousness to a computer, that feels as if it's choosing to do and how to do a calculation, it doesn't seem reasonable to say that the calculation would no longer be valid, on account of its consciousness being an illusion, yet this question seems to imply this would be the case for the brain. For computers, this calculation is a result of computer circuitry. For brains, our methods are a result of neural activity.

Illusions (by one definition, at least) are commonly the result of something. If you see an optical illusion where it looks like some static spiral is rotating. The spiral still exists, even if it isn't rotating. If you see an illusion of the Loch Ness monster because of some tree in the distance, the tree still exists. For epiphenomenalism, what exists would be neural activity.

It may be helpful to compare this to functionalism (or reductive materialism, which holds similar views as far as what I'm focusing on here).

To me, it seems that between epiphenomenalism and functionalism, the line is rather blurry, and may largely be due to semantic differences (in the definitions of "exists", "illusion", "consciousness", and potentially more). Both philosophies hold that consciousness is a result of the physical, but the functionalist position is that the chemical reactions happening in your brain is what consciousness is, whereas the epiphenomenalist position says that the separate resulting experience from those reactions is what we'll call consciousness.

Some views on eliminative materialism may say those reactions happen and define what you do and experience, but "consciousness", or certain mental states, are fundamentally flawed concepts. Dennett, for example, argues that people under the influence of morphine have reported experiencing excruciating pain without it being unpleasant, which seems to contradict the intrinsic unpleasantness of pain. This is not to say that you don't experience something we call pain, but rather how we categorise that experience may be incorrect.

A rejection of the concept of "free will", due to it being ill-defined, is also related. This is to not say you don't feel as if you're "freely" making decisions, but rather that your decisions are merely determined by biological and environmental factors. One could say that free will "doesn't exist" while still accepting that you have the experience of freely making decisions.

Much of eliminative materialism seems to consist of pointing out that how we understand various subjective human experiences may be flawed, rather than trying to claim that you aren't having those experiences.

There may also be some materialist views that don't just boil down to semantic or categorisation differences when compared to other materialist views.

One could potentially also say that we're unable to observe the experience of consciousness, therefore it should be excluded from our model from reality, regardless of whether it exists in any objective sense. Although observing the effects of consciousness is possible (by e.g. observing how other people act), and there's plenty in physics, for example, that we only know about due to their effects. Then again, one might say any observed effects of consciousness are due to neural activity.

Views on eliminative materialism could theoretically go beyond the above and say that experiences described by some/all mental states aren't actually experienced. Only at this point do you get to something which can potentially classify as self-refuting, but I'd instead just say it's trivially false, on account of us having those experiences. I am, however, not sure if anyone actually holds such a view on eliminative materialism, and if someone does, how they'd respond here.

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    The analogy with computers fails because their results are meaningless without a mind to interpret them. E.g. if your program is meant to compute the result for 1+1, an output of "10" will be wrong in decimal but correct in binary. On a physical level, even bits don't exist except as interpretations we give to electrical signals which by themselves aren't binary, and with enough gerrymandering even your wall's atoms are running Word. Cf. Is the Brain a Digital Computer
    – Mutoh
    Sep 18, 2023 at 20:50
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    @Mutoh An AI can go about its business in a virtual world with no humans interpreting the results. A robot can go about its business in the real world with no humans interpreting the results (they're a lot less autonomous there, if for no other reason than because they're not yet advanced enough to get anywhere near being self-sustaining or reproducing). In both cases, we do interpret the results, because we built and program them with some intended purpose.
    – NotThatGuy
    Sep 18, 2023 at 21:31
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    @Mutoh I don't know that you can actually do enough gerrymandering for that. For every clock cycle, the space of current state + history grows exponentially: even assuming a classical universe, I don't think you'd be able to get past the startup sequence of Word before you run out of wall to creatively-interpret. Temperature is similarly subjective – you can change the temperature of an object via creative reinterpretation of the facts – but the more creative the interpretation, the harder it is to physically instantiate.
    – wizzwizz4
    Sep 18, 2023 at 22:48
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    @infatuated Do you agree that computers can do valid calculations, despite not having consciousness? If we were to somehow attach a consciousness to a computer, that feels as if it's choosing to do and how to do a calculation, would that calculation suddenly stop being valid, on account of its consciousness being an illusion?
    – NotThatGuy
    Sep 19, 2023 at 7:47
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    @infatuated You refusing to call it a "calculation" doesn't change the fact that computers process input to produce output that is identical to what you'd get from a "calculation", and such things, and more, allow them to do things in an environment with a fair amount of autonomy. "Concepts are mental phenomena, and since computers have no mind..." - that's where you'd lose eliminative and some other materialists, since they may consider "concepts", "mental phenomena" and/or "mind" to be ill-defined, or they may view those things as emergent, which could theoretically extend to computers.
    – NotThatGuy
    Sep 19, 2023 at 9:55

From 2018 Scientific American article There Is No Such Thing as Conscious Thought

Would you agree that we are much more unconscious than we think we are?

I would rather say that consciousness is not what we generally think it is. It is not direct awareness of our inner world of thoughts and judgments but a highly inferential process that only gives us the impression of immediacy.

That's all well and good. Nevertheless, the conditioned existence of things depends on cognition so somewhere in that process one's reality is being produced. In this phenomenological vein I would make a point on the OP's comment:

I may hallucinate a phoenix but that would be an illusion for it doesn't correspond to anything in the outer world.

What is experienced as 'world' is already an ambiguous state of affairs, e.g. from Heidegger's The Origin of the Work of Art, page 31

the clearing is pervaded by a constant concealment in the twofold form of refusal and obstructing. Fundamentally, the ordinary is not ordinary; it is extra-ordinary, uncanny.

From this ambiguous presentation of 'world' one makes a best guess of what is real and possible, which constitues one's reality. So now if a phoenix appears one might judge this inconsistent with one's broader view of what is real. At no point does one know "the outer world", except perhaps for its surface as it is received by the senses and conditioned by thought.

The counterpoint view comes from an understandable bias for scientific realism and consensus reality. From that approach there is the hard problem of consciousness. But from the phenomenological approach, conscious experience is the starting point, not an intractably difficult problem.


The area of philosophy you are asking about is a very convoluted one. There are a great many different streams and directions, argued often by single philosophers or very small groups; often contradicting other streams completely, or (sometimes more difficult) shifting their meaning in subtle ways.

If you read Wikipedia's overview on Eliminative Materialism, you find lots and lots of accounts of philosophers arguing in this or that direction. You cannot, as far as I can tell, talk of "eliminative materialism" as one single, well-focused entity.

To single out some of the individual parts of your question as best I can (I admit that I have not done deep studies of eliminiative materialism, but I have passing familiarity with many of the other topics of theory of mind):

  • "Illusion" is not necessarily only related to true/false values, or imagining something, etc., but can well be simply an User Illusion - meaning a simplification of reality. It seems perfectly acceptable that whatever happens with light waves hitting someone's eye balls is most certainly ending up in a simplified way at ... wherever it ends up. In fact, the very first step in optical processing in our eyes is that the utterly chaotic stream of ungodly amounts of photons is reduced to a dead simple intensity level (of a relatively narrow spectrum) in each of our rods and cones - literally a single number. So whatever we see most definitely is a "User Illusion" already at that point.
  • To expound on this: obviously while our rods and cones give us a pixelated view of the universe, that is hardly our subjective impression. Our consciousness perceives an apple, not a million of red pixels. So obviously some kind of processing has to go on between the rods and cones and ... wherever the information about the apple ends up in our minds. This not only means more simplification (reducing a million pixels to a single entity with a handful of abstract attributes), but also some kind of expansion (i.e., our brain might remember the last time its body tasted this kind of apple; or it might, from the particular highlights on the skin of the apple, conclude that the apple is wet, and so on and forth) which means that as soon as the rods/cones are agitated, an involuntary, unconscious process starts within the brain, transforming the pixels into a more conceptual entity, dragging out memories, maybe spiking emotions. If we're in a day-to-day mode and not paying attention to philosophical details, we might attribute some of that to the actual object itself erroneously (i.e., someone might say "the yummy apple" - where "yummy" certainly is not an attribute of the apple itself; someone else might hate apples and might end up with "the disgusting apple"). All of this could be added to the User Illusion of the apple when not paying attention to the details.
  • From a short review of M.E. it seems to be that quite a few of the philosophers do not mean to say that consciousness does not exist, but they mean that what our consciousness perceives as consciousness (or qualia, or emotion, or whatever M.E. tries to eliminate) is at least an illusion in the aforementioned sense of the User Illusion. If consciousness is somehow aware that it is conscious, then it seems perfectly acceptable, or even par for the course, that this awareness (whatever it is, physically) is extremely simplified, modified or abstracted, just as the visual impression from the previous example. Not once has consciousness ever perceived "seeing" as a storm of photons; it seems highly improbable that whatever consciousness perceives as consciousness actually is what it seems to be. In this regard, it seems totally naturally that all phenomena that are playing out in front of our consciousness, indeed, are (user) illusions.
  • (N.B. when looking at this from an engineering perspective, this would make perfect sense: one of the main functions and evolutionary justification of the "feature" consciousness could be that its main job is to reduce the complexity of the world to abstract, more easily handled bits of information - hence, illusions.)
  • There are plenty of other examples: for example, famously when looking at the brain in very short time spans, it seems plausible that we do things before we actually decide to do them, all the while "feeling" that we decided to do the thing ourselves. This goes in the direction of Free Will or the question whether there is a separate "capital-S Self" sitting somewhere in your brain. These experiments suggest that there are parts of our brain that are capable of narrating internally why we came to some decision after the fact. And our conscience usually seems to be quite incapable of detecting this or being aware of it, unless we think really hard about it. So it may just be that the actual decision-making is just completely distributed in our brain matter; and that we have a separate layer whose main job is to fool our consciousness (whatever that may be) into thinking (duh) that something or someone is at the "helm".


  • The question is not about whether consciousness exists or does not exist, but whether our intuitive "folk psychology" explanation of consciousness (and self, qualia, emotions, intentions and so on and forth) can have any relevance at all, seeing as everything we see, hear, feel etc. is filtered heavily, and thus it can be easily assumed that anything we seem to know about our internal workings of the brain/mind is filtered just the same.
  • M.E. does not seem to be overall nihilistic; it wishes to specifically open up our minds to delve more into neuroscience and other materialistic/physical approaches to understand why we do what we do, or why we seem to feel what we feel.
  • Thank you for sympathetic response and providing additional thought. I agree how the entire field is so complex and branched out which makes it difficult to follow. And I agree that everyday consciousness doesn't normally reflect many facts of the phenomenal world, whether photons, God or angels (if they exist). However, what's still amazing is that the same thing can grow to learn about these things, and that how gaining knowledge of such counter-intuitive facts occurs, again, within our consciousness! That is, we still rely on consciousness to make it richer, more accurate or more complete!
    – infatuated
    Sep 19, 2023 at 14:08
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    It's mind-boggling for sure, @infatuated!
    – AnoE
    Sep 20, 2023 at 8:44

It is indeed the ultimate absurdity! The proposal is internally contradictory. The longest blind alley in modern philosophy - and bullshit! In contrast, a simpler proposal based on ancient philosophy. The only thing that I know for certain is that I am a thinking being. I can reasonably infer the existence of other minds. I use reason to observe the world and draw conclusions from these observations. As a scientist, I find the proposal that human consciousness does not have a survival advantage absurd.


You say :

The ultimate absurdity: if consciousness is an illusion, how can anything we know be real?

I see two problems here :

  1. Materialism is still the prevailing ideology in Western thinking, although in the Standard Model of particle physics, matter is not a fundamental concept because the elementary constituents of atoms are quantum entities which do not have an inherent "size" or "volume" in any everyday sense of the word.
  2. Resoning as currently understood in Western thinking, is ill defined as it has been seperated from its teleological roots. As a consequence of this, "real" is not understood as a fundamental property of the behavioural aspect of things, but as something that has to be proved, as if reality needs a formalization to exist.

Quantum physics is challenging both of these established views, because if you look closer what is says is that matter IS NOT the fundamental substance in nature and causality IS teleological. What remains though, is for these concepts to be integrated back into our ontological representation of reality as the mainstream philosophical paradigm.

  • What would "Western thinking" be? The thoughts of John Wayne?
    – Olivier5
    Nov 29, 2023 at 12:37
  • @Olivier5, a way of thinking that originated in the age of enlightenment and leading to its end. en.m.wikipedia.org/wiki/Age_of_Enlightenment Nov 29, 2023 at 14:53
  • That's a very broad and heterogenous set. Spinoza and Kant, for instance, were not materialists. Diderot was, but Rousseau wasn't. Descartes was famously dualist. Etc.
    – Olivier5
    Nov 29, 2023 at 17:09
  • It seems to me that your answer makes some hasty generalizations. At most you could say that materialism remains dominant among academic philosophers in western countries, or something like that. I'm not even sure that's true, though.
    – Olivier5
    Nov 29, 2023 at 17:17
  • @Olivier5, sciences and politics are molding the world now, philosophers just follow the waves these days... Nov 29, 2023 at 20:39

We don't know that anything is real. However, our interactions with the world seem to follow rules, despite their illusory nature. Consciousness is a structured illusion, not an arbitrary dream.

Test this! Try to bend reality to your imaginary whims; you'll find that it doesn't work. Why not? Apparently reality isn't that malleable. At the same time, e.g. from quantum mechanics, we know that reality is neither fully deterministic nor fully predetermined; we do, to some degree, create reality by participating in it.


I can't believe I read this whole thread. Now I'm thinking the Universe is an image on a large computer monitor that is recreated at 60 Hz. Why do we fear death?

The answer is that at the basis of all we know is faith. We trust academics. We have faith that reality is what we perceive. We know only by faith, because nothing can be proved beyond any doubt!

Certainly each person's conscious awareness contains shortcuts that permit them to integrate their experience into objective reality. The more emotional pain a person has endured, the further from others his perceptions will be, because everyone must reconcile their experience to objective reality.

This is usually done through sweeping generalizations that prove to be severe limitations to their own well-being, especially when it comes to the brokenhearted, who adopt positions in opposition to all members of the opposite sex. People wouldn't do that if they were not conscious. However, each persons perceptions differ from all others.

Limitations on human intellect make man essentially blind to predestination. However, since no such limits exist on stupidity, the illusion of free will persists.

  • Welcome to Philosophy.SE! It would help your case if you were to clarify how your examples help to refute eliminativism (specifically, eliminativists will take issue with your references to pain and being brokenhearted—they classify such terms as "folk psychology"). Also it's not clear how sexism plays into the OP's concerns.
    – Hokon
    Sep 20, 2023 at 4:39

I agree that there is no way conscious experience itself can be an illusion because of the reasons stated by OP. It simply makes no sense. However, I do believe that our idea of what consciousness is is very likely an illusion. There are a lot of reasons why, but with this I largely look to the Attention Schema Theory (AST) of consciousness.

Basically, the brain forms a highly simplified model of its own attentional system in order to reduce the complexity of reality. This "simplified model" goes on to form a further simplified model of itself that we know as consciousness. There is no way for a conscious being to fundamentally know what the idea of consciousness is; there must be a model of consciousness.

The point I'm trying to make is that consciousness is different from conscious experience, yet people often use the terms interchangeably.

  • You make an interesting point. It would have been helpful to have given us some basic references on Attention Schema Theory, and perhaps a more detailed discussion.
    – Ludwig V
    Jan 2 at 6:56

We may be able to "explain" everything, if we eliminate perception, but we will be unable to account for everything. An account of knowledge does not just ask how it is that the apple fell to earth or how we know that it did. It also allows us to doubt that it did (and offer philosophical insight into this). As you suggest, one way of viewing that is through the emblem of 'illusion'.

  • that may be utter nonsense. i failed that module
    – user67675
    Sep 18, 2023 at 8:00

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