Peterdjones comments on The raw-experience dogma: Dissolving the “qualia” problem - Less Wrong
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My use of "depend" was not meant to exlude identity. I had in mind the supervenience principle, which is trivially fulfilled by identity.
I am not sure where you got that from. C I Lewis defined qualia as a "sort of universal", but I don't think there was any implication that everyone sees 600nm radiation identicallty. OTOH, ones personal qualia must recur to a good degree of accuracy or one would be able to make no sense of ones sensory input.
Interestingly, that is completely false. Knowing that a bat-on-LSD's qualia are identical to its brain states tells me nohting about what they are (which is to say what they seem like to the bat in question..which is to say what they are, since qualia are by definition seemings.[If you think there are two or three meanings of "are" going on there, you might be right]).
Agreed. I was just making sure that we aren't talking about some sort of Platonic-realm qualia, or mysterious quantum-entanglement qualia, etc. That's why I personally dislike the word "qualia"; it's too overloaded.
If I am correct, then you personally could never know exactly what another being experiences when it looks at the same red object that you're looking at. You may only emulate this knowledge approximately, by looking at how its brain states correlate with yours. Since another human's brain states are pretty similar to yours, your emulation will be fairly accurate. A bat's brain is quite different from yours, and thus your emulation will not be nearly as accurate.
However, this is not the same thing as saying, "bats don't experience the color red (*)". They just experience it differently from humans. I don't see this as a problem that needs solving, though I could be missing something.
(*) Assuming that bats have color receptors in their eyes; I forgot whether they do or not.
I don't think anyone has raised that except you.
Alhough, under may circumstances, I could know approximately.
Bats have a sense that humans don't have, sonar, and if they have qualia, they presumably have some kind of radically unfamiliar-to-humans qualia to go with it. That is an issue of a different order to not knowing exactly what someone else's Red is like. And, again, it is not a problem solved by positing the identity of the the bat's brain state and its qualia. Identity theory does't explain qualia in the sense of explaining how variations in qualia relate to varations in brain state.
Agreed.
I wasn't talking about sonar, but about good old-fashioned color perception. A bat's brain is very different from a human's. Thus, while you can approximate another human's perception fairly well, your approximation of a bat's perception would be quite inexact.
I'm not sure I understand what you mean. If we could scan a bat's brain, and understand more or less how it worked (which, today, we can't do), then we could trace the changes in its states that would propagate throughout the bat when red photons hit its eyes. We could say, "aha, at this point, the bat will likely experience something vaguely similar to what we do, when red photons hit our eyes". And we could predict the changes in the bat's model of the world that will occur as the result. For example, if the bat is conditioned to fear the color red for some reason, we could say, "the bat will identify this area of its environment as dangerous, and will seek to avoid it", etc.
If the above is true, then what is there left to explain ?
Radically unfamiliar-to-humans qualia. You have picked an easy case, I have picked a difficult one. If we wan't to know what the world sonars like to a bat on LSD, identity theory doens't tell us.
Well, in point of fact, I've personally never done LSD, so I don't know what color perception is like for another human on LSD, either. I could make an educated guess, though.
In case of the bat sonar, the answer is even simpler, IMO: we lack the capacity to experience what the world sonars like to a bat, except in the vaguest terms. Again, I don't see this is a problem. Bats have sonars, we don't.
Note that this is very different from saying something like "we can't know whether bats experience anything at all through their sonar", or "even if we have scanned the bat's brain, we can't predict what changes it would undergo in response to a particular sonar signal", etc. All I'm saying is, "we cannot create a sufficiently accurate mapping between our brain states and the bat's, as far as sonaring is concerned".
Again, I'm not entirely sure I understand what additional things we need to explain w.r.t qualia.
I see that as a problem for the claim that mind-brain identity theory explains qualia. It does not enable us to undestand the bat's qualia, or to predict what they would be like. However, other explanations do lead to understanding and predicting.
Understanding and predicting.
I guess I'm not entirely sure what you mean by "understanding" and "predicting". As I said, if we could scan the bat's brain and figure out how all of its subsystems influence each other, we would know with a very high degree of certainty what happens to it when the bat receives a sonar signal. We could identify the changes in the bat's model of the world that would result from the sonar signal, and we could predict them ahead of time.
Thus, for example, we could say, "if the bat is in mid-flight, and hungry, and detects its sonar reflecting from a small object A of size B and shape C etc., then it would alter its model of the world to include a probable moth at the object's approximate location (*). It would then alter course to intercept the moth, by sending out signals to its wing muscles as follows: blah blah".
Are predictions of this sort insufficient ? If so, what additional predictions could be made by those other explanations you mentioned ?
(*) Disclaimer: I don't really know much about the hunting habits of real-life bats.
More irrelevant. None of them are actualy about qualia, about how things seem to experiencing subjects. You have Substituted an Easier Problem.
Is "how things seem to experiencing subjects" somehow different from "things happening to the brains of experiencing subjects" ? If so, how ?
Normally I'd assume that I know what you meant and move on, but since this involves LSD... You don't know what it's like? Or you do, but it's an educated guess? What?
I've never done LSD myself, but I've talked to people who did, and I've read similar accounts in books, online, etc. Thus, I can make a guess as to what LSD would feel like, assuming my brain is close to the average.