If one of the "confabulations" were true, how would you know?
Which one? Ontologically fundamental mental entities? Show me one that isn't an empty label. The other three -- denying the existence of subjective experience, p-zombie explanations, and interpreting correlation with a physical phenomenon as identity all miss the mark. They are not things that even could be explanations. That's probably not an exhaustive list -- it can't be, if there really is an explanation -- but vague hypotheticals don't help. Show me a purported explanation of the existence of subjective experience that isn't an example of one of these four fallacies and then there will be something to talk about.
Likewise for if no one knew how it worked, but thought they knew how it could possibly work; how would you know if they were right aside from having a full explanation?
Well, how would you know if someone was right about the mechanism of high-temperature superconductivity? You would look at whatever they did -- theoretical modelling, experiments, whatever -- and judge whether the reasoning and the experimental setup were sound. You would compare it with other work in the field. You might do theoretical and experimental investigations of your own.
This is intended to be a simple answer to a simple question. The same sort of processes are how you would judge any explanation of the existence of subjective experience.
Here, for example, is an imaginary explanation of consciousness: control systems are conscious! Firstly, even accepting that all living organisms are chock full of control systems, this is an example of fallacy no.4: finding a physical phenomenon apparently causally linked with consciousness and saying the two are the same. But leaving that aside, one can very easily find control systems in the human brain that are inaccessible to consciousness: motor control. When you move an arm you are not aware of the individual muscles you are operating. Even when you learn a complex motor skill like juggling, the processes by which the cerebellum learns the task are completely inaccessible to you. So there's a large and complex collection of control systems sitting right next to and intimately connected with what appears to be the physical substrate of consciousness, and is made of very similar stuff, yet itself is devoid of the property. This refutes the proposed explanation.
Easy, yes?
They are not things that even could be explanations
I don't understand what single thing, if any, disqualifies them. Tell me if I'm wrong, but I think you would agree they have unique issues, just as "being an empty label" is something that won't be wrong with, say, denying subjective experience.
You made a good point about the inexhaustibility of wrong explanations, which I suppose is true for everything. So I certainly don't ask for anything like a complete list of bad explanations and their problems! But of the other three you mentioned, do ...
Weisberg et al. (2008) presented subjects with two explanations for psychological phenomena (e.g. attentional blink). Some subjects got the regular explanation, and other subjects got the 'with neuroscience' explanation that included purposely irrelevant verbiage saying that "brain scans indicate" some part of the brain already known to be involved in that psychological process caused the process to occur.
And yet, Yale cognitive science students rated the 'with neuroscience' explanations as more satisfying than the regular explanations.
Why? The purposely irrelevant neuroscience verbiage could only be important to the explanation if somebody thought that perhaps it's not the brain that was producing certain psychological phenomena. But these are Yale cognitive science students. Somehow I suspect people who chose to study cognition as information processing are less likely than average to believe the mind runs on magic. But then, why would they be additionally persuaded by information suggesting only that the brain causes psychological phenomena?
In another study, McCabe & Castel (2008) showed subjects fictional articles summarizing scientific results and including either no image, a brain scan image, or a bar graph. Subjects were asked to rate the soundness of scientific reasoning in the article, and they gave the highest ratings when the article included a brain scan image. But why should this be?
I remember talking to a friend about free will. She was a long-time physicalist who liked reading about physics and neuroscience for fun, but she didn't read Less Wrong and she thought she had contra-causal (libertarian) free will.
"Okay," I said. "So the brain is made of atoms, and atoms move according to deterministic physical law, right?"
"Right," she said.
"Okay. Now, think about the physical state of the entire universe one moment before you decided to say "Right" instead of something else, or instead of just nodding your head. If all those atoms, including the atoms in your brain, have to move to their next spot according to physical law, then could you have said anything else than what you did say in the next moment?" (Neither of us understood many-worlds yet, so you can assume we're talking about a single Everett branch.)
She paused. "Huh. I'll have to think about that."
"Also, have you heard about those studies where brain scans told researchers what the subjects were going to do before the subjects consciously decided what they were going to do?"
"No! Are you serious?"
"Yup. Sometimes they could predict the subject's choice 10 seconds before the subject consciously 'made' the choice."
"10 seconds? Wow. I didn't know that."
I think that maybe the 'with neuroscience' explanations and brain scan images are more satisfying partly because they remind us we're physicalists. They remind us that reductionism marches on, that psychology is produced by physical neurons we can take pictures of.
Just like most people, physicalists walk around all day with the subjective experience of a 'unity of consciousness' and contra-causal free will and so on. If a physicalist isn't a researcher who studies all the latest successful reductions in neuroscience or biology or physics all week long, and doesn't read Less Wrong every day, then it's possible to get lost in the feel of everyday experience and thus be surprised by a headline like 'Brain Scanners Can See Your Decisions Before You Make Them.'
Sometimes even physicalists need to be reminded — with concrete reductionistic details — that they are physicalists. Otherwise their normal human anti-reductionistic intuitions may creep back in of their own accord. That's one reason it helps to study many sciences, so you have many successful reductions in your head, and see (at some resolution) the entire picture, from psychology to atoms. As Eliezer wrote:
To her credit, my friend no longer believes in contra-causal free will.