It is obviously true that "🟩", "greenness", and "activity in the visual cortex" are not identical things. For example, "greenness" is one word containing the letter "g", but not the letter "a", whereas "activity in the visual cortex" is five words containing the letter "a", but not the letter "g", and "🟩" does not contain any letters at all.

Usually, when someone says that "🟩" is "greenness", they do not mean that the word "greenness", in a thought, spoken, or written form, is strictly identical to "🟩", or that "🟩" does not exist, and only "greenness" does. What they mean is that "greenness" is a useful label to describe "🟩". It is generally understood that labels are not the things that they are describing.

This understanding breaks somewhat when discussing illusionism - which can, at least partially, be attributed to illusionists not being very good at explaining their position.

When someone says that "🟩" is "greenness", we do not accuse that person of denying the existence of "🟩". Why then, when someone says that "🟩" is "activity in the visual cortex", do we make such an accusation?

An illusionist would not deny the existence of "🟩" (perhaps some illusionists would, Keith Frankish certainly does not). An illusionist would merely claim that so far, the most useful framework that has been discovered for verbally reasoning about "🟩" is the framework of brain configurations and activity in the visual cortex.

Some would say that the analogy presented here is unfair, because the word "greenness" generally only has one referent, whereas the phrase "activity in the visual cortex", according to illusionism as explained here, has at least two referents, namely "🟩" and micromovements in a grey, squishy, and wet object.

However, that does not make the analogy unfair. The core claim I am attempting to refute here is that illusionists somehow deny the existence of "🟩". That a term has multiple referents is irrelevant as an objection to my refutation.

Another point that could be raised is that it is not evident that the framework of activity in the visual cortex is the most useful framework in which to reason about "🟩". That point however is also irrelevant as an objection to my claim that illusionists do not deny the existence of "🟩" when they say that "🟩" is "activity in the visual cortex" - analogously to how people do not deny the existence of "🟩" when they say that "🟩" is "greenness".

It could indeed be true that there exist more useful frameworks for reasoning about "🟩". But one should understand what illusionism says before attempting to argue against it.

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When someone says that “🟩” is “greenness”, we do not accuse that person of denying the existence of “🟩”. Why then, when someone says that “🟩” is “activity in the visual cortex”, do we make such an accusation?

That isn't a statement of illusionism, it's statement of reductionism or identity theory.

What would the statement of illusionism be then? That 🟩 is an illusion? Surely, yes, but digging deeper, you would get to some form of brain activity.


Illusionists thinks the illusion is brain activity, yes.

Illusionism is the doctrine that phenomenal consciousness does not exist. Frankish introduced the term, so it makes sense to anchor it to his usage.

In the essay “Illusionism as a Theory of Consciousness”, Frankish makes very clear that he is not advocating a “conservative realist” position in which phenomenal properties can be reduced to brain states. Illusionism is in fact ideologically close to dualism - both agree that phenomenal properties are too weird to be explained by physical phenomena, they just disagree on what to make of this. He distinguishes between weak illusionism and strong illusionism - weak illusionists deny some of phenomenal consciousness’s putative features, whereas strong illusionism denies that it exists altogether. Illusionism is to be understood as strong illusionism. Finally, illusionism should not be understood as the denial of experiences altogether - we have sensations like pain and color, it is just that introspection falsely depicts them as possessing phenomenal properties.

NOW, there is definitely room for confusion and equivocation here, because the meaning of “phenomenal consciousness” is not perfectly clear. The main idea seems to be that introspection systematically misrepresents our own experiences in a way that gives rise to dualist intuitions. At this point I lose a grip on what is meant by statements like “An illusionist would not deny the existence of 🟩”

Interesting. What is the difference then between illusionism and eliminativism? Is eliminativism the even more "hard-core" position, whereby while illusionism only denies the existence of phenomenal properties, but not experience, eliminativism denies the existence of any experience altogether?

Hmm. It gets tricky because we get into like, what does the English word “experience” mean. “Phenomenal properties” is supposed to pick out the WOW! aspect of experiences, that thing that’s really obvious and vivid that makes us speculate about dualism and zombies. I think Frankish uses “experience” basically to mean whatever neural events cause us to talk about pain, hunger etc, so I don’t think an eliminativist would deny those exist. But I’m not sure.

I think you need to think through your definition of "exist" and whether it matches that of those who think that illusionism denies the existence of greenness, without quotes.

To expand a bit, I think this post is confusing ontological and ontic existence, or in LW terms mixing up existence in the map and existence in the territory.

Yes, and I think it is worse than that. Even existence in the map is not clearcut. As I said in the other comment, do dragons exist in the map? In what sense? Do they also exist in the territory, given that you can go and buy a figurine of one?

It is my impression that certain people think that illusionists deny that there is any 🟩 even in the map, and I have never heard any illusionist make that argument (maybe I just haven’t been paying enough attention though). The conversation seems to be getting stuck somewhere at the level of misunderstandings concerning labels and referents. The key insight that I am trying to communicate here is that when we say that A is B, we generally do not mean that A is strictly identical to B - which it clearly isn’t. This applies even when we say things like 2+2 = 4. Obviously, "2+2" and "4" are not even close to being identical. Everyone understands this, and everyone understands that when we say that 2+2 = 4, we use two different sets of symbols to refer to one single mathematical object. 

Claiming that greenness is activity in the visual cortex does not amount to denying that there is 🟩. 

But again, perhaps I just misunderstand illusionism (although not even Keith Frankish himself would deny that there is 🟩, see the video linked in the post). Are there any illusionists around here who are claiming that 🟩 is not?

As a side note, perhaps I will stop using the verb "to exist" altogether, and instead start using "to be".

when we say that A is B, we generally do not mean that A is strictly identical to B - which it clearly isn’t. This applies even when we say things like 2+2 = 4. Obviously, "2+2" and "4" are not even close to being identical.

This seems to mix up labels and referents. 2+2 is strictly identical to 4. The statement “2+2=4” is not the same as the statement “‘2+2’=‘4’”

The referent of the label 2+2 is strictly identical to the referent of the label 4, but the labels 2+2 and 4 themselves are obviously not identical.

I am beginning to think that I should not have used the quotes at all. I used them more or less as a highlighting tool, perhaps a different font style would accomplish this better. I might edit the post. Regarding existence, I am using the verb "to exist" as synonymous with the verb "to be". And it is my impression that illusionists generally do not deny that (not going to use any quotes this time) 🟩 is. If some here do, I would be interested in hearing their arguments. 

This is a rabbit hole, but existence of something is far from a clear-cut settled question. Do numbers exist? Do fairies exist? Does nothing(ness) exist? 

FYI, your U+1F7E9 LARGE GREEN SQUARE may not render correctly for all readers. (I see only a placeholder box, for example.)

I recommend using U+1F49A GREEN HEART (💚), as it is an older code point and thus likely to be viewable by readers using a wider range of client platforms.

In that case, perhaps I could leave it as an exercise for the reader to deduce what was there originally. Maybe it could be a good intelligence test for GPT-4...

More seriously, the reason I am reluctant to use the heart is that a heart shape is usually mentally associated with all kinds of things that are entirely irrelevant to this discussion, and could generate confusion. When writing the post, I chose the green square in a deliberate manner as the shape least likely to be distracting. 

Of course, if most readers see a placeholder box, it will generate even more confusion, so... To edit or not to edit, that is the question.