Most people don't know the word "qualia". Nonetheless, most people will state something equivalent....that they have feelings and seemings that they can't fully describe. So it's a "speaking prose" thing.

There are many reasons why a person might struggle to describe their experiences that wouldn't be due to them having qualia or having some implicit qualia-based theory, especially among laypeople who are not experienced at describing their mental states. It would be difficult to distinguish these other reasons from reasons having to do with qualia.

So I don't agree that what you describe would necessarily be equivalent, and I don't think it would be easy to provide empirical evidence specifically of the notion that people have or think they have qualia, or speak or think in a way best explained by them having qualia.

Even if it could be done, I don't know of any empirical evidence that would support this claim. Maybe there is some. But I don't have a high prior on any empirical investigation into how laypeople think turning out to support your claim, either.

And something like that is implicit in Illusionism. Illusionism attempts to explain away reports of ineffable subjective sensations, reports of qualia like things. If no one had such beliefs, or made such reports, there would be nothing for Illusionism to address.

You know, I think you're right. And I believe the course of this discussion has clarified things for me sufficiently for me to recognize that I do not, strictly speaking, endorse illusionism.

Illusionism could be construed as the conjunction of two claims:

(1) On introspection, people systematically misrepresent their experiential states as having phenomenal properties.

(2) There are no such phenomenal properties.

For instance, Frankish (2016) defines (strong) illusionism as the view that:

“[...] phenomenal consciousness is illusory; experiences do not really have qualitative, ‘what-it’s-like’ properties, whether physical or non-physical” (p. 15)

Like illusionists, I deny that there are phenomenal properties, qualia, what-its-likeness, and so on. In that sense, I deny phenomenal realism (Mandik, 2016). As such, I agree with (2) above. Thus, I agree with the central claim of illusionism, that there are no phenomenal properties, and I deny that there are qualia, or that there’s “what it’s likeness” and so on. However, what I am less comfortable doing is presuming that things seem this way to nonphilosophers, and that they are all systematically subject to some kind of error. In that regard, I do not fully agree with illusionists.

To the extent that illusionists mistakenly suppose that people are subject to an illusion, we could call this meta-illusionism. Mandik distinguishes meta-illusionism from illusionism as follows:

“The gist of meta-illusionism is that it rejects phenomenal realism while also insisting that no one is actually under the illusion that there are so-called phenomenal properties” (pp. 140-141).

Mandik goes on to distance his position from illusionism, in reference to Frankish as follows:

“One thing Frankish and I have in common is that neither of us wants to assert that there are any properties instantiated that are referred to or picked out by the phrase ‘phenomenal properties’. One place where Frankish and I part ways is over whether that phrase is sufficiently meaningful for there to be a worthwhile research programme investigating how it comes to seem to people that their experiences instantiate any such properties. Like Frankish, I’m happy with terms like ‘experience’, ‘consciousness’, and ‘conscious experience’ and join Frankish in using what he calls ‘weak’ and functional construals of such terms. But, unlike Frankish, I see no use at all, not even an illusionist one, for the term ‘phenomenal’ and its ilk. The term ‘phenomenal’, as used in contemporary philosophy of mind, is a technical term. I am aware of no non-technical English word or phrase that is accepted as its direct analogue. Unlike technical terms in maths and physics, which are introduced with explicit definitions, ‘phenomenal’ has no such definition. What we find instead of an explicit definition are other technical terms treated as interchangeable synonyms. Frankish follows common practice in philosophy of mind when he treats ‘phenomenal’ as interchangeable with, for instance, ‘qualitative’ or, in scare-quotes, ‘“feely”’. (p. 141)

I can’t quote the whole article (though it’s short), but he concludes this point by stating that:

“We have then, in place of an explicit definition of ‘phenomenal properties’, a circular chain of interchangeable technical terms — a chain with very few links, and little to relate those links to nontechnical terminology. The circle, then, is vicious. I’m sceptical that any properties seem ‘phenomenal’ to anyone because this vicious circle gives me very little idea what seeming ‘phenomenal’ would be.” (p. 142)

Mandik is not so sure he wants to endorse meta-illusionism, since this might turn on concerns about what it means for something to be an illusion, and because he’s reluctant to state that illusionists are themselves subject to an illusionism. What he proposes instead is qualia quietism, the view that:

“the terms ‘qualia’, ‘phenomenal properties’, etc. lack sufficient content for anything informative to be said in either affirming or denying their existence. Affirming the existence of what? Denying the existence of what? Maintaining as illusory a representation of what? No comment. No comment. No comment” (p. 148)

This is much closer to what I think than illusionism proper. So, in addition to denying that there are qualia, or phenomenal properties, or whatever other set of terminology is used to characterize some putative set of special properties that spell trouble for those of us ill-disposed to believe in such things, I also deny that it seems this way to nonphilosophers.

My entire academic career has centered on critiquing work in experimental philosophy, and close scrutiny of this and related articles might reveal what I take to be significant methodological problems. Nevertheless, insofar as research has been conducted on the subject of whether nonphilosophers have phenomenal properties, or think about consciousness in the same way as philosophers, at least some of the results indicate that they may not. See here, for instance Sytsma & Machery (2010):

Abstract: “Do philosophers and ordinary people conceive of subjective experience in the same way? In this article, we argue that they do not and that the philosophical concept of phenomenal consciousness does not coincide with the folk conception. We first offer experimental support for the hypothesis that philosophers and ordinary people conceive of subjective experience in markedly different ways. We then explore experimentally the folk conception, proposing that for the folk, subjective experience is closely linked to valence. We conclude by considering the implications of our findings for a central issue in the philosophy of mind, the hard problem of consciousness.”

I doubt this one study is definitive evidence one way or the other. What I will say, though, is that whether people think of consciousness the way philosophers do is an empirical question. I suspect they don’t, and absent any good reasons to think that they do, I’m not inclined to accept without argument that they do.

Trying to attack qualia from every possible angle is rather self-defeating. For instance, if you literally don't know what "qualia" means, you can't report that you have none. And if no one even seems to have qualia, there is nothing for Illusionism to do. And so on.

I disagree. You can claim to both not know what something means, and claim to not have the thing in question.

In some cases, you might not know what something means because you’re ignorant of what is meant by the concept in question. For instance, someone might use the term “zown zair” to refer to brown hair. I might not know this, even if I do have brown hair. In that case, I would not know what they mean, even though I do have brown hair. It would be a mistake for me to think that because I don’t know what they mean, that I don’t have “zown zair.” And it would be foolish to insist both that “zown zair” is false, and that “zown zair” is meaningless. I would simply have failed to find out what they were referring to with the term.

But this is not the case with qualia. I am not merely claiming that I don’t understand the concept. I am claiming that nobody understands the concept, because it is fundamentally confused and meaningless.

First, in the course of an exchange, This is especially the case when one is responding to a host of people, over an extended period of time, who are incapable of explaining the putative concept in a way that isn’t circular or vacuous.

In the course of an exchange, people may employ a concept. They might say that, e.g. some objects have the property A. Yet when asked to explain what A is, they are unable to do so, or they provide unsatisfactory attempts. For instance, they might point to several objects, and say “all these objects have property A.” This is what was done earlier in this thread: I was given examples, as though this was independently helpful in understanding the concept. It’s not. If I pointed to a truck, a flock of geese, and a math textbook and said “these all have property A,” you wouldn’t be much closer to knowing what I was talking about. In other cases, they might use metaphors. But the metaphors may be unilluminating. In still other cases, they might appeal to other terms or concepts. Yet these terms or concepts might themselves be obscure or poorly defined, and if one asks for clarification, one begins the journey through an endless loop of mutual interdefinitions that never get you anywhere.

In such cases, it can become apparent that a person’s concepts are circular and self-referential, and don’t really describe anything about the way the world is. They might define A in terms of B, B in terms of C, and C in terms of A. And they might insist that A is a property we all have.

When numerous people all claim that we have property A, but they cannot define it, one may reasonably wonder whether all of these people are confused or mistaken. That is, one might conclude that property A is a pseudoconcept, something vague and meaningless.

In such cases, I am fine saying both that

(a) I don’t have property A

(b) I don’t know what people referring to property A are talking about

I can believe that (a), because it’s meaningless. I don’t have meaningless properties. And I can conclude that (b), because it’s meaningless. I can’t understand a meaningless concept, because there isn’t anything to understand.

Maybe that’s an awkward way of framing why one would reject circular concepts that ascribe meaningless properties to people, in which case I’d be happy to revise the way I frame my rejection of qualia.

But then , why insist that you are right? If you have something like colour blindness , then why insist that everyone else is deluded when they report colours?

There are very good reasons to think people can see colors, and one would have such reasons even if they were colorblind. We can point to the physical mechanisms involved in color detection, the properties of light, and so on. We can point to specific color words in our and other languages, and it would be fairly easy to determine that nonphilosophers can see colors. I don’t think any of these conditions apply to qualia. So, first, there's that.

To emphasize just the last of these, I don’t think “everyone else” is deluded. I think philosophers are deluded, and that people who encounter the work of these philosophers often become deluded as well. I don’t think the notion of qualia is a psychological mistake so much as it is an intellectual mistake only a subset of people make.

I suspect such mistakes are endemic to philosophy. The same thing has occurred, to an alarming extent, in contemporary metaethics. Moral realists frequently invoke the notion of decisive or external reasons, irreducible normativity, categorical imperatives, stance-independent normative and evaluative facts, and so on. I reject all of these concepts as fundamentally confused. And yet philosophers like Parfit, Huemer, Cuneo, and others have not only tangled themselves into knots of confusion, their work has trickled out into the broader culture. I routinely encounter people who have come across their work claiming to “have” concepts that they are incapable of expressing. And these philosophers, when pressed, will fall back on claiming that the concepts in question are “brute” or “primitive” or “unanalyzable,” which is to say, they can’t give an account of them, and don’t think that they need to. Maybe they do "have" these concepts, but since I am very confident we can explain everything there is to now about the way the world is without invoking them, I suspect they're vacuous nonsense, and that these philosophers are uniformly confused.

And, like the notion of qualia, philosophers have for a long time presumed that ordinary people tend to be moral realists (see e.g. Sinclair, 2012). My own academic work specifically focuses on this question. And like the question of what people think about consciousness, this, too, is an empirical question. So far, little empirical evidence supports the conclusion that ordinary people tend to be moral realists, or at least that they tend to be consistently and uniformly committed to some kind of moral realism. By and large, they struggle to understand what they are being asked (Bush & Moss, 2020). I suspect, instead, that something like Gill’s (2009) indeterminacy-variability thesis is much more likely: that people have variable but (I suspect mostly) indeterminate metaethical standards.

The same may turn out to be the case for the only other issue I looked into: free will. This has led me, in my own work, to point towards the broader possibility that many of the positions philosophers purport to be intuitive, and that they claim are widespread among nonphilosophers, simply aren’t. Rather, I suspect that philosophers are over-intellectualizing some initial pool of considerations, then generating theories that are neither implicitly nor explicitly part of the way ordinary people speak or think.

I don’t think this is a situation where I am color blind, while others have color vision. Rather, it’s more like recognizing that many of the people around you are subject to a collective, and contagious, hallucination. So I suspect, instead, that I have come to recognize over time that academic philosophy has played an alarming role in duping large numbers of people into a wide range of confusions, then duped them further by convincing them that these confusions are shared by nonphilosophers.

References

Bush, L. S., & Moss, D. (2020). Misunderstanding Metaethics: Difficulties Measuring Folk Objectivism and Relativism. Diametros, 17(64). 6-21

Frankish, K. (2016). Illusionism as a theory of consciousness. Journal of Consciousness Studies, 23(11-12), 11-39.

Gill, M. B. (2009). Indeterminacy and variability in meta-ethics. Philosophical studies, 145(2), 215-234.

Mandik, P. (2016). Meta-illusionism and qualia quietism. Journal of Consciousness Studies, 23(11-12), 140-148.

Sinclair, N. (2012). Moral realism, face-values and presumptions. Analytic Philosophy, 53(2). 158-179