I understand that the belief in qualia may be based on a sensual illusion, but I can't get my head around illusionism. Obviously, illusionists deny that we experience any illusion, we just believe (or not) that we do.

But I am absolutely certain that, supposing qualia do not exist, I am experiencing (through touch, hearing etc.) the illusion of qualia. Isn't it up to them to account not for the belief or statement of belief but what it expresses? That's vacuously impossible, if the belief is true.

According to illusionists (Dennett 2019, 2020; Frankish 2016; Kammerer 2021), conscious experience is an illusion. It certainly seems to us that conscious experiences, and thus qualia (at least in sense (1) of the four senses distinguished at the beginning of this entry) exist, but in reality there are no such things. Qualia are like Santa Claus and the Easter Bunny (Dennett 2020). It is not being denied here that through the use of our senses, we genuinely encounter a wide range of qualities, for example, in perception, colors, auditory qualities such as pitch and loudness, various textures and aromas. But the qualities so encountered are not properties of experiences; for we do not genuinely undergo any experiences. To be sure, when we introspect, it certainly seems to us that we are the subjects of experiences with widely varying phenomenal character. But we are wrong... This position is not easy to take seriously; for what could be more obvious than the existence of conscious experience? Adherents of the view may respond that introspection simply leads us astray. On the basis of introspection, we believe that we undergo experiences (states with qualia in sense (1)), but the beliefs so formed are false. What would help strong illusionism here is a theory of introspection which can explain the apparent absurdity of the view.

What sort of argument would suffice to shift the burden of proof onto someone who claims they have experiences?

  • i guess i'm just shifting the burden of proof
    – user71083
    Commented Jan 17 at 5:42
  • Qualia are considered to be the most simple type of conscious perception. Please give a reference for the claim that qualia are illusions. - I do not understand the last sentence of your question, could you please clarify.
    – Jo Wehler
    Commented Jan 17 at 5:46
  • The polar opposite of illusionism, panpsychism, provokes incredulous stare too. As did non-Euclidean geometry, until it didn't, incredulity dissipates with habit. If they are right that we are compelled into mistaken experiential beliefs "100% certainty about experiences" will make no difference, we are still mistaken. But it is on them to explain how the compulsion works, see Kammerer for a version of it.
    – Conifold
    Commented Jan 17 at 5:50
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    Illusion here simply means error, maybe replace the word will be better for you?... Commented Jan 17 at 6:55
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    See this answer to understand what the illusionists are saying and why. philosophy.stackexchange.com/questions/61897/… Raw data should generally be taken as real, but if there is strong enough justification to do so, it can be dismissed. The justification that Blackmore provides -- is NOT strong enough to justify throwing out data she does not want to believe.
    – Dcleve
    Commented Jan 19 at 6:34

4 Answers 4


There is an important difference between qualia and Father Christmas which Dennett foolishly overlooks: viz, there is a convincing and vastly more plausible alternative explanation for why presents appear at Christmas.

I have read and listened to hours of Dennett and Frankish, and at the end of that investment of intellectual effort I have no more inkling of what they were saying than at the start. They might well be on to a good idea, but they have not developed it beyond an empty speculation. If the illusionists reach the point at which they are able to explain why we experience the detailed, vivid, consistent, nuanced etc etc illusion of sight, for example, then they will have shifted the burden of proof to the point at which I would give the idea fresh consideration. My expectation, however, is that we will find that the difference between the illusionists and the rest of us actually boils down to just a difference in labelling- they use the word illusion where we use qualia, and neither gives any insight into what is really happening.

  • i can accept that some people are not certain they have experiences, but not that they believe they do not (let alone conceive of their reasons for claiming otherwise)
    – user71083
    Commented Jan 17 at 7:35
  • Your last remark about labelling - especially the idea that "they use the word illusion where we use qualia, and neither gives any insight into what is really happening." is brilliant and very helpful to me, since I don't agree with either. But much will depend on how we interpret that "really" in really happening. Most people will probably go for some form of physicalism. Others will go for no explanation possible. Both have points in their favour. Neither is really convincing. Which repeats the problem at a different level. Frustration again!
    – Ludwig V
    Commented Jan 17 at 7:41
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    Daniel Dennett in a Guardian interview: "I really don't like academic bullies, these silverbacks in whatever field who resort to bullying. Overpowering people with their prestige and rhetoric. It's an abuse of power." – nice statement, but when reading Dennett, I always feel bullied by him. He uses too much rhetoric that only works because of the prestige of the natural sciences.
    – viuser
    Commented Jan 17 at 20:08
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    @viuser Indeed. In this exchange he is quite nasty to Searle nybooks.com/articles/1995/12/21/…
    – Minsky
    Commented Jan 17 at 21:40

If qualia were an illusion, then it would only seem to us that we are experiencing qualia, when in fact we are not. We may think of one bucket, containing the qualia that we actually experience, which is empty. And then a second bucket containing the qualia that it seems we experience, which is full of all sorts of things.

The problem with this picture is that a quale is defined by how it seems. If it seems you perceive quale X, then by definition, you perceive quale X. Everything in bucket 2 automatically also goes in bucket 1.

If that is not sufficiently convincing, then set it aside. Very well, let us suppose again that bucket 1 is empty. It remains for Dennett and the like to explain the contents of bucket 2. And it seems that explaining the contents of bucket 2 is very difficult. Indeed it seems that explaining the contents of bucket 2 is just as difficult as explaining qualia in the first place. It's practically the same task.


The trouble with qualia is their qualitative character which poses a challenge to, ex. functionalist theories of mind. Under such a theory, there would be no difference between a 180 degree change in our reaction to color qualia and the famous inverted color spectrum thought experiment, because the causal role which these functionalised qualia play wouldn't change. Qualia, however, are claimed to be only subjectively available, causally transparent etc. and thus cannot be subjected to such analysis.

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    The functionalist answer is that there just cannot be an inverted-qualia color spectrum without changing the functional behavior of the brain. The subjective character of a color is a function of its causal relationships with other colors and other ideas, e.g. red subjectively is the way it is because of its associations with strawberries, sunsets, orange and purple, etc. Consider what would happen if someone's color qualia spectrum suddenly inverted; they would remark on it. That remark would be a functional difference, which must have been caused by a change in the brain.
    – causative
    Commented Jan 17 at 18:01
  • @causative Yes, you're correct in regards to colour, but I'm going off the notion of qualia which talks about 'intrinsicness'. I'm mostly repeating what Gil Harman said in his articles regarding functionalism and qualia.
    – user71009
    Commented Jan 17 at 18:25

What sort of argument would suffice to shift the burden of proof onto someone who claims they have experiences?

This is difficult, because I have not read Dennett on this particular point, and so I can't pretend to speak for him. But it seems to me that even the slightest weakening of Dennett's position is sufficient to entirely shift the burden of proof.

Introspection tells us shockingly little: It tells us that we subjectively experience something. But it does not tell us what this "something" is supposed to be. What is conscious experience? Is it physical? Non-physical? Measurable? Does it inhere in neurons, functional relationships, or something else entirely? Those are, in some sense, the easy questions that physicalists and dualists have been arguing over for centuries.

There's a much more fundamental issue here: How do we know that conscious experience has any substance beyond our subjective experience of it? What if conscious experience is confined to each individual's inner world, and has no physical or non-physical realization other than that subjective experience? If any other object, besides conscious experience, had the property of only existing in one person's mind, we would not hesitate to call that object an "illusion." Perhaps this is what Dennett means when he asserts that consciousness is an "illusion" - not that the subjective experience does not exist, but rather that there is nothing underlying the subjective experience - that it is just a subjective experience, without any objective reality behind it. Introspection has no answer for this - it can tell us that the subjective experience exists, but no more.

Personally, I'm not entirely convinced by this explanation. The argument seems to posit that we can have mental experiences that have no physical component, and I'm not sure that a physicalist like Dennett would make or accept a claim like that. It is, however, totally compatible with epiphenomenalism, so I could certainly imagine another philosopher holding this view.

It may yet be possible to weaken this argument further in order to allow for physicalism. We might hold that consciousness exists as a subjective experience and a family of functional brain-state relationships (or whatever brand of physicalism you like), but that it gives no deeper insight into what the brain as a whole is "actually" doing (for example, when we consciously experience ourselves making a decision, the decision has already been made by some subconscious part of the brain, and we merely experience a simulacrum of the decision-making process). The problem is, this is such a weakening of the argument that I'm not sure it's compatible with the word "illusion" anymore. Under this view, it would make more sense to call consciousness a "facade" or "simplification" of the underlying mental processes.

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