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Peterdjones comments on Three consistent positions for computationalists - Less Wrong
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It isn't intended to answer your question about neuroscience.It is intended to pose the philosopher's question about the limitations of physicalism. If physicalism is limited, that eventually folds back to your question, since one way of explaining the limitation of physicalism is that there are non-physical things going on.
When she steps outside, something physical happens in her brain that has never happened before. Maybe something "non-physical" (huh?) also happens, maybe it doesn't. We have gained no insight.
If we agree that she learns something on stepping outside we have learnt that a version of physicalism is false.
Can you state what that version is? Whatever it is, it's nothing I subscribe to, and I call myself a physicalist.
There are broadly speaking two versions of physicalism: ontological physicalism, according to which everything that exists is material, spatio-temporal, etc; and epistemological physicalism, according to which everything can be explained in physical terms. Physicalism can be challenged by the inexplicability of qualia in two ways. Firstly, qualia might be physically inexplicable because they are not physical things, which contradicts ontological physicalim. Secondly, the phsyical inexplicability of qualia might be down to their having a first-person epistemology, which contradicts epistemological physicalism. Epistemological physicalism requires that eveything be explicable in physical terms, which implies that everything is explicable in objective, descriptive, public, third-person terms. If there are some things which can only be known by acquantance, subjectively, in first person terms, then it is not the case that everything can be explained in physicalese. However, ontological physicalism could still hold.
Or, you could notice that the apparent inexplicability of qualia is a sign that you are confused. ;-)
OK. You understand qualia, Please de-confuse me on the subject.
Have you read the LessWrong Sequences yet?
I have. I don't understand qualia either. Do you have a particular relevant link you were thinking of?
ps: "You should really read the sequences" is telling people to read 1,000,000 words or go away, and as such is functionally equivalent to an extremely rude dismissal. Please don't do that. Link to a particular post if you actually think the pointer is helpful, i.e. make it an actually helpful pointer rather than a functionally rude one.
There is a difference between telling someone to go read the sequences, and asking if someone has read the sequences. If you ask, the other person is allowed to say "no, I haven't", and that is useful to know what sort of inferential distances would be appropiate in your explanation.
Did you try section 2.5 of "Good and Real"?
Neither do I. However, having understood (a certain subset of) the sequences, I am capable of dissolving nonsensical questions about qualia... which is what most discussion of qualia consists of. (I.e., nonsense questions and confusion.)
The uses of words, the mind projection fallacy, reductionism, and part of QM are probably the sequences with the most important tools for dissolving that sort of confusion.
Some of them. I have read Block, Chalmers, Dennet, Flanagan, Jackson, Levin, Nagel, Searle, etc, etc as well. Which sequence did you have in mind?
For this discussion, the one of principal relevance is the one on the use of words, especially the mind projection fallacy (including the non-existence of mental or supernatural entities). Reductionism would be useful as well, and quantum physics.
The quantum physics part is particularly helpful for disabusing one's self of many naive intuitions about object identity, that otherwise lead to belief in things like souls, or consciousness as something separate from bodies, or the idea that an exact duplicate of you wouldn't actually be you. If you don't get at least that much about the basics of physics, then it's way too easy to believe in fairy tales when they have words like "consciousness" and "qualia" attached.
In other words, human beings are born with various intuitions (hardwired into the brain, as has been shown by experiments on babies who can't even talk yet) that, without sufficient education, we use as the basis for reasoning about minds and reality. Huge amounts of philosophy and "common sense" reasoning are then based on these false premises.
Of course, this makes most philosophical discussions equivalent to nothing but hot air: reasoning based on false premises. Attempting to refute the conclusions without first refuting the premises is pointless, which is why I keep pointing to the Sequences. They contain the necessary information to refute the premises that support the vast majority of philosophical and supernatural nonsense. (Such as some of Chalmers's and Searle's, for example.)
Of course, if you don't agree that physics, cognitive science, and Bayesian updates based on them are the basis for reaching an objective conclusion, then this discussion is entirely moot. That's why I asked whether you've read the sequences -- and implicitly, accept their premises about the nature of reasoning, as well as the specific facts of physics and cognitive science -- so I can determine whether there's anything worth talking about.
My conclusion in the Mary's room thought experiment doesn't challenge either of these versions: something new happens when she steps outside, and there's a perfectly good purely physical explanation of what and why. It is nothing more than an artifact of how human brains are built that Mary is unable to make the same physical thing happen, with the same result, without the assistance of either red light or appropriate surgical tools. A slightly more evolved Mary with a few extra neurons leading into her hippocampus would have no such difficulty.
Incidentally, while agreeing with your main point, I feel I ought to challenge the implications of "more evolved." This has nothing to do with Mary's position on some scale of evolution; she could be "less evolved" and have those neurons, or "more evolved" and lack them.
I should have predicted that somebody here was going to call me on that. I accept the correction.
Mary still doesn't have to make anything special happen to her brain have knowledge of anything else. She can still understand photosynthesis without photosynthesising.
She can understand the sequence of chemical reactions that comprises the Calvin cycle just as she can understand what neural impulses occur when red light strikes retinal rods, but she can't form the memory of either one occurring within her body.
Which, yet again, only matters if there is something special about qualia that requires memory or instantiation in the body to be understood. She can understand the Calvin Cycle full stop.