Apparently my reply is "too long", so I'll reply in two parts.

PART 1:

Sorry, you're right, I tend to do that a lot :-(

Hey, apparently I do too!

That's correct, I think

Excellent.

I think it's not entirely clear what that pathway is, but there are some very good clues regarding what that pathway could be, since certain aspects of consciousness (such as vision, f.ex.) are reasonably well understood.

Um... Sure, let's go with that. There's a nuance here that's disregarding the hard problem, but I don't think we'll get much mileage repeating the same kind of detail-focusing we've been doing. :-P

I think we should make a distinction between a person's own qualia, as experienced by the person, and the qualia of other people, from the point of view of that same person. Let's call the person's own qualia "P" and everyone else's qualia (from the point of view of the person) "Q".

Sure, agreed.

I should warn you, though, that I'm not sure that this distinction is coherent. There's some reason to suspect that our perception of others as conscious is part of how we construct our sense of self. So, it might not make sense to talk about "my" conscious experience as distinct from "your" conscious experience as though we start with a self and then grant it consciousness. It might be the other way around.

I emphasize this because explaining Q without ever touching P might not tell us much about P. If we start with conscious experience and then define the line between "my" experience and "others'" experience by the distinction between P and Q, all we do by detailing Q is explain our impression that others are conscious. We might think we're addressing others' P, but we never actually address our P (which, it seems, is the only P we can ever have access to - which might be because we define "me" in part by "that which has access to P" and "not me" by "that which doesn't have access to P").

So with that warning, I'll just run with the intuitive distinction between P and Q that I believe you're suggesting.

Obviously, each person individually can detect P. Until some sort of telepathy gets developed (assuming that such a thing is possible in principle), no person can detect Q (at least, not directly).

I agree, and I would go just a little bit farther: I would argue that it's not possible even in principle to detect Q as a kind of P. If I experience another person's experience from a first-person perspective, it's not their experience anymore. It's mine. Sure, we might share it, like two people watching the same movie. But the P I have access to is still my own, and the Q that I'm supposedly accessing as a kind of P is still removed: I still have to assume that the person sitting next to me is also experiencing the movie.

You seem to be saying -- and I could be wrong about this, so I apologize in advance if that's the case -- that, in order to build a general theory of consciousness, we need to figure out a way to study P in an objective way. This is hard (I would say, impossible), since P is by its nature subjective, and thus inaccessible to anyone other than yourself.

Yeah, I think that's a reasonably fair summary. :-)

I, on the other hand, am arguing that a general theory of consciousness can be built based solely on the same kind of evidence that compels us to believe that other people experience things -- i.e., that Q exists and is reducible to brain states.

I agree with you on this. I just think it's important to recognize that what we will have explained is our impression that others are conscious. That might give us insight into P, and it seems implausible that it wouldn't, but it also doesn't seem clear what kind of mechanism it could possibly reveal for P. At least to me!

I think you would you agree that such a model can, in principle, exist (though please correct me if I'm wrong).

Yes, I agree.

Then, would you agree that this model can also predict what you, yourself, will experience in a given situation ? If not, then why not ? If yes, then how is P any different from Q ?

I'm going to go with "maybe", which I think requires me to answer both the "yes" and "no" branches. :-P

I think it's certainly plausible that this model of Q could predict the behavior of P. But it needn't do so. Why not? Because P and Q are different for precisely the reason that we gave them different names. I'm under the impression that my wife is conscious as a sort of immediate perception; surely I deduce it somehow, probably by my perception of her as a social entity with whom I could in principle interact, but that isn't how it seems to me. I just see her as conscious. So when we explore my perception of her as conscious and we develop a thorough model of her consciousness as perceived by me (and others), what that model does is predict how our perception of her conscious experience changes.

But it requires an extra step to say that if I were her, I would be experiencing those changes as P.

Now, I suspect that this model would work out just fine. I suspect that when we determine that we've modeled Q, that the model of Q will predict my P. (I see this in the Enneagram all the time, in fact: it describes others' experiences, and when I spell out their experiences they often give an "I've been caught!" kind of reaction. When someone does the same to me, I sure feel caught!) After all, part of the impression I get of Q comes from the fact that I know that I would react they way the other is reacting if I were to experience X, which draws me to think that they're experiencing X. So for it to fail to model P, it seems likely that I'd have to react in a way that I would not recognize from the outside (assuming experiencing my own P as Q can be turned into a coherent idea). That seems like it'd be pretty weird.

But we're still left with the fact that the application of the theory to Q feels tremendously different than its application to P. The fact that the model is attempting to explain in part why P and Q are different in the first place makes it difficult for me to see how an explanation of Q alone is going to do it. It feels as though its ability to capture P would be almost coincidental.

(continued...)