The point of the thought experiment is to ask if Mary would interpret the experience of seeing the specific color with her own eyes as a new experience. If yes, and given the premise that she knows everything that it is possible to know about the physics of color and the human brain, the conclusion is supposed to be that an experience is not a physical fact of the world.

I have written another comment on why I think this conclusion is wrong.

> The conclusion is supposed to be that an experience is not a physical fact of the world.

I see what you're getting at and mostly agree (hence the Upvote!). But...

Whether a 1st person qualitative experience is a "physical fact of the world" depends on your level of description. In a sense, it's not an epistemically objective physical fact that I can share with others. However, it is just a brute ontological physical fact of the world that my mind experiences the color red (even if yours doesn't).

This is precisely where we need to clarify "facts of the world". We can't settle this chat until we introduce the notion of subjective vs objective, and epistemic vs ontological.

Note that I personally believe the argument is deeply flawed, and rests on some assumptions about the human mind that may turn out to be false; and that shouldn't be generalized to other potential minds (say, AGI) even if they are true of human minds.

I was just explaining what I believe to be the core of the argument.

I think the fallacy is to treat knowledge of redness as a "fact" about the world.

In general, when you learn a fact, you acquire information about the world that previously you lacked. But when you first experience redness, your knowledge of the world is exactly the same as it was when you were stll Monochrome Mary. The old Mary knew which things were red, like tomatoes; she was fully-informed about the nature of light and colour. The experience of redness has added nothing to her knowledge of tomatoes and their colour.

If that's correct, then familiarity with any qualia fails to be a kind of knowledge.

> But when you first experience redness, your knowledge of the world is exactly the same as it was when you were still Monochrome Mary.

That is still false though, because in that moment Mary realizes what redness looks like. She has mapped a sense experience to a concept, which is new knowledge. The author has to prove that this mapping exercise is indeed not new knowledge, as making a connection between two disparate events (acquisition of concept vs acquisition of experience) is considered net new knowledge based on the epistemical definition of knowledge.

See my update below.

> The author has to prove that this mapping exercise is indeed not new knowledge...

Is that what you meant to write? It seems that "the author" here is referring to the paper's author (Frank Jackson), but his whole argument depends on the premise that the result of this mapping exercise is new knowledge.

It is acceptable English usage to call what Mary learns on release "knowledge", but it is not knowledge in the form of a proposition that you believe to be true; it is the memory of an experience (and whatever connections are made from that experience), and materialism does not claim or imply that you can gain the latter from reading it in a book.

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Update: With respect to the phrase I quoted, I see what you mean. This knowledge (if that is what it is) is new to Mary, but unless it existed and was knowable before Mary was released, the argument fails to show some knowledge that Mary did not know then but was knowledge at the time.

Jackson attempts to get around this by saying that she learns something about other people - specifically, that her conception of the mental life of other people was incomplete before her release and more complete after. Insofar as that conception includes objective facts, however, Mary could know those facts beforehand. Seeing colors might modify her personal justification for believing those facts (along the lines of "previously, I accepted it on the basis of what I learned verbally but now I accept it on the basis of my experience"), but note the "my experience" in that phrase: those experiences did not exist until after her release, so this justification was not available to Mary beforehand.

I don't think that's a substantial problem. We can reformulate the argument like this: assume that brain states correspond 1:1 to mind states. As such, for any qualia there would be a corresponding brain state. If Mary fully understands all details about light and the human mind and brain, she would be able to understand the brain state that would correspond to the qualia of her experiencing a red object. As such, she should be able to put her brain in that state.

If then she exits the room and actually looks at the color red, and if this experience is new to her, it follows that her brain is in a state that it has never been in before, which is a contradiction.

The original claim argues that this contradiction should be taken to mean that the first assumption is wrong - that brain states can't correspond 1:1 to mental states, or, equivalently, that there is no brain state that corresponds 1:1 to a qualia.

However, I believe that there is another premise which seems more obviously flawed, and which doesn't follow from this original one. That flawed assumption is that Mary could put her brain in any state she understands. I believe it's quite plausible that Mary could fully understand the brain state that corresponds to the qualia for seeing red, but still be unable to actually put her brain in that state.

In general, we don't seem to have any direct conscious control of our brain processes, just as much as we can't consciously control the function of our liver or pancreas.

Sorry, but I didn't take Mary's 'complete' knowledge of physics to mean that she also has insight into the workings of her own mind, still less that she can manipulate it. Justy knowing all of physics is superhuman enough.

And as it happens, I don't generally buy arguments premised on the mind being reducible to the brain.

It's part of the argument thoigh:

> She knows all the physical facts about us and our environment, in a wide sense of 'physical' which includes everything in completed physics, chemistry, and neurophysiology (emp. mine), and all there is to know about the causal and relational facts consequent upon all this, including of course functional roles.

If she knows all there is to know about neurophisiology, she obviously knows exactly how her own brain works. In the original assumption of physicalism (the one the argument ultimately wants to show is false), that also implies she knows everything about the mind.

> And as it happens, I don't generally buy arguments premised on the mind being reducible to the brain.

The whole point of this particular argument is to take that as an assumption, reach a contradiction, and conclude that the assumption is false. The Mary's Room argument is precisely an argument that the mind is separate from the brain. It's a bad argument (per some other comment, even it's creator no longer really thinks it's convincing), but I think you would agree with the conclusion.

> which includes everything in completed physics, chemistry, and neurophysiology

"Completed", which I take to mean stuff that someone already understands, now. But nobody understands how changes at a neurophysiological level affect mental states and thoughts. At best, we can say that some mental states are correlated with some neurophys. phenomena.

> she obviously knows exactly how her own brain works.

Not if I have correctly understood what author meant by "completed". Nobody knows exactly how a brain works.

I believe "completed" means precisely the opposite - current physical theories are incomplete, but Mary has access to the completed version. Otherwise, the whole argument would only prove that qualia are not part of currently understood physical theories, which not even the most convinced physicalist would contest I think.

> Additionally, while Mary may only receive information in black and white, she perceives in full colour and can see the colours of her own skin and clothes.

No, she doesn't (and never has) perceived in full color. Her entire world has been modified (Truman Show style) to shield her from ALL color at ALL times.