Theories using Piercian concepts are today usually termed antirealist or instrumentalist.

Tabooing "truth", one can see that the theories really speak about (slightly) different concepts.

Then, you would merely choose which of the concepts is the one needed for a particular theoretical purpose. Right?

Wrong! The arguments go to the concepts' coherence. This is why it's philosophy, not lexicography.

For example, a correspondence theorist generally argues that the notion of an epistemological limit to which scientific findings converge need not exist and can never be established empirically. If correspondence theory is true, you aren't allowed to use the Piercian limit. It's a vacuous concept.

Or, the correspondence theorist argues that the epistemological limit of scientific investigation can't even be defined without assuming a correspondence variety of truth (which the Piercian, in turn, argues can't exist). The correspondentist argues that if you define truth at a limit, then you have to define the truth that science is converging as itself the result of a scientific investigation at an endpoint, and similarly for the concepts you use to define scientific investigation, etc. Thus, a Piercian view, it's contended, produces an infinite regress.

It's possible that both concepts are coherent, but that too would require a philosophical argument--and it's an unlikely result here, at least in my opinion: it's probably more likely that both concepts are incoherent than that both are coherent.

These kinds of conclusions, philosophical and lacking in direct application, help inform the priors one assigns to just about every scientific controversy.

me: A "p-zombie" "behaves" the same way we do, but does a p-zombie believe it has qualitative awareness?

To be precise about the value of the belief/intuition concept in accounting for the illusion that qualia exist—one defect in the zombie thought experiment is that it prompts the attitude: maybe I can't prove that you're not a zombie, but I sure as hell know I'm not one!

The zombie experiment imposes a consistent outside view; it seems to deny the evidence of "personal experience" by fiat—because it simply doesn't address what it would feel like to be a zombie.

So, the zombie experiment seems to show that people might not be able to distinguish zombies from humans; but invoking the beliefs held by the "zombie" shows from the inside that being a zombie can be no different from being a human: the two are subjectively indistinguishable.

To address your question directly: the ordinary zombie thought experiments purport to show that without qualia humans would be zombies; whereas when you allow zombies' (false) beliefs (in ineffable perceptual essences), the thought experiment shows that zombies are really humans.

Sophistry. It's madness to say that the blue isn't actually there. But this is tempting for people who like the science we have, because the blue isn't there in that model of reality.

If by blue you mean--as you do--the purely subjective aspect of perceiving the color blue (call that "blue"), then it's only madness to deny it exists if you insist on confusing blue with "blue." No one but a madman would say blue doesn't exist; no philosopher should be caught saying "blue" exists.

If you can show a causal role for pure experience, that would be something else, but instead you speak of the "causal role they appear to play." But we don't want a theory where things play the role they "appear" to play; the illusion of conscious experience includes the seemingness that qualia play a causal role (Added: as I explain in my account of the related illusion of "free will."

In short, it just won't do to call qualia nihilism "madness," when you offer no arguments, only exasperation.

But modern physics is mathematical and operational, there is plenty of opportunity for something to actually be a conscious experience, while appearing in the formal theory as a state or entity with certain abstractly characterized structural and algebraic properties.

This simply doesn't solve the problem; not in the least. If you posit abstractly characterized structural entities, you are still left with the problem regarding what makes that configuration give the appearance "blue." You're also left with the problem of explaining why evolution would have provided a means of registering these "abstractly characterized structural and algebraic properties" when they make no difference for adaptation.

My guess, you espouse an epistemology that makes sense data necessary. Completely freeing epistemology from sensationalism is virtue rather than vice: philosophers have been looking for a way out of sensationalism since Karl Popper's failed falsificationism.

You need an argument better than alleging madness. Many things seem blatantly wrong before one reflects on them.

You may be omitting or misunderstanding the role of the concept of belief in my account. The role of that concept is original in this account (and novel, to the best of my less-than-comprehensive knowledge).

A "p-zombie" "behaves" the same way we do, but does a p-zombie believe it has qualitative awareness? If it does, then there's no distinction between humans and p-zombies, but the antimaterialists who came up with the p-zombie thought experiment were of the persuasion that belief is as meaningless a concept for materialists as is qualia; both were then derogated by the reigning behaviorists as "mentalistic" concepts, hence illicit. The Churchlands are eliminitivist about all "folk psychological" concepts like belief; Dennett doesn't apply the concept of belief to the problem of qualia. But qualia proponents make belief dependent on qualitative awareness: eliminating qualia does preclude deriving knowledge (a kind of belief) from conscious sensation.

On my account, what dissolves the problem of qualia is recognizing that the only "evidence" favoring their existence is our sense of certainty favoring our sequestered belief that they exist. (See 3.C. in OP.)

Is your position the same as Dennett's position (summarized in the second paragraph of synopsis here)?

Let me try to answer more succinctly. Dennett and I are concerned with different problems; Dennett's is a problem within science proper, while mine is traditionally philosophical. Dennett's conclusion is that "qualia" don't provide introspective access to the functioning of the brain; my conclusion is that our common intuition concerning the existence of qualia is incoherent.

"If nothing exists, I want to know how the nothing works and why it seems to be so highly ordered."

If qualia are explained by our innate intuitions (or beliefs)—propositional attitudes—then two questions follow about "how it works":

1. What is the propositional content of the beliefs?

2. What evolutionary pressures caused their development?

I make some conjectures in another essay.

If one accepts the principle of identity of indistinguishable, then it follows that quarks or points must be distinguishable (since they can be non-identical)

I accept the principle, but I think it isn't relevant to this part of the problem. I can best elaborate by first dealing with another point.

There is no separate criterion for the identity of sets which leads to the conclusion that Q is identical to Q\Bob, so we do not have a contradiction

True, but my claim is that there is a separate criterion for identity for actually realized sets. It arises exactly from the principle of the identity of indistinguishables. Q and Q/Bob are indistinguishable when the elements are indistinguishable; they should be distinguishable despite the elements being indistinguishable.

What justifies "suspending" the identity of indistinguishables when you talk about elements is that it's legitimate to talk about a set of things you consider metaphysically impossible. It's legitimate to talk about a set of Platonic points, none distinguishable from another except in being different from one another. We can easily conceive (but not picture) a set of 10 Platonic points, where selecting Bob doesn't differ from selecting Sam, but taking Bob and Sam differs from taking just Bob or just Sam. So, the identity of indistinguishables shouldn't apply to the elements of a set, where we must represent various metaphysical views. But if you accept the identity of indistinguishables, an infinite set containing Bob where Bob isn't distinguishable from Sam or Bill is identical to an infinite set without Bob.

Believe me, if there was an obvious contradiction in Zermelo-Fraenkel set theory (which includes an axiom of infinity), mathematicians would have noticed it by now.

I'll take your word on that, but I don't think it's relevant here. I think this is an argument in metaphysics rather than in mathematics. It deals in the implications of "actual realization." (Metaphysical issues, I think, are about coherence, just not mathematical coherence; the contradictions are conceptual rather than mathematical.) I don't think "actual realization" is a mathematical concept; otherwise--to return full circle--mathematics could decide whether Tegmark's right.

Among metaphysicians, infinity has gotten a free ride, the reason seeming to be that once you accept there's a consistent mathematical concept of infinity, the question of whether there are any actually realized infinities seems empirical.

Here's my interpretation of what you're saying: Let the set of all quarks be Q, and assume Q has infinite elements. Now pick a particular quark, let's call it Bob, and remove it from the set Q. Call the new set thus formed Q\Bob. Now, it's true that Q\Bob has the same number of elements as Q. But your claim seems to be stronger, that Q\Bob is in fact the same set as Q. If that is the case, then Q\Bob both is and isn't the set of all quarks and we have a contradiction. But why should I believe Q\Bob is identical to Q?

Because there is no difference between Q and Q/Bob besides that Q/Bob contains Bob, a difference I'm trying to bracket: distinctions between individual quarks.

Instead of quarks, speak of points in Platonic heaven. Say there are infinitely many of them, and they have no defining individuality. The set Platonic points and the set of Platonic points points plus one are different sets: they contain different elements. Yet, in contradiction, they are the same set: there is no way to distinguish them.

Platonic points are potentially problematic in a way quarks aren't. (For one thing, they don't really exist.) But they bring out what I regard as the contradiction in actually realized infinite sets: infinite sets can sometimes be distinguished only by their cardinality, and then sets that are different (because they are formed by adding or subtracting elements) are the same (because they subsequently aren't distinguishable).