In 1982, Frank Jackson published an article entitled "Epiphenomenal Qualia" in Philosophical Quarterly 32:127. Within it, he outlined a thought experiment known as "Mary's Room", or "Mary and the Black-and-White Room". 
Imagine a scientist called Mary. She is born and raised within a black-and-white room, where she experiences no colours. Mary is a talented scientist, and learns an enormous amount about the physics of colour, the mechanism by which the human eye detects colour, and the pathways through which colour is interpreted within the brain.
One day, Mary steps out the door of her black-and-white room and into the world, and experiences colour for the first time. The question posed by the thought experiment is this: what does Mary learn at this moment?
Jackson presents this thought experiment originally as a refutation of Physicalism, and a demonstration of the non-physical nature of mental states.
It seems just obvious that she will learn something about the world and our visual experience of it. But then is it inescapable that her previous knowledge was incomplete. But she had all the physical information. Ergo there is more to have than that, and Physicalism is false.
The thought experiment strikes at the heart of qualia, the subjective conscious experience. What does Mary learn? What is the difference between Mary before she stepped through this door, and afterwards? In thinking about this, I remain unconvinced that this is a refutation of Physicalism.
Let us extend this thought experiment a little. Imagine that we have a device that can implant memories into a brain so perfectly that there is no test that you can reasonably perform to distinguish between a real and artificial memory. As far as I can tell, such a device (though incredibly complicated) would be possible.
Now let us imagine that we implant a memory into Mary's brain of her leaving the room and experiencing colour, before returning to the room. Let us assume that there is no evidence of that journey other than the memory and no test that Mary can perform to ascertain whether the event actually happened - no expectation of a green blade of grass stuck on a shoe or anything like that. What then is the difference in qualia between this version of Mary and the version of Mary that did genuinely leave the room?
My immediate thought is that this difference depends on Mary's beliefs and knowledge around that memory. Firstly, consider that if Mary is cognisant of the implantation and the artificiality of the memory, then it seems as if the memory will be just another piece of information amongst many and that - critically - actually experiencing the outside would still generate a new and novel experience. In such a scenario, there remains some qualia that separates the implanted memory from the real experience.
But consider the scenario where Mary believes those implanted memories to be real. What happens to this qualia? It seems to disappear. The nature of that qualia therefore seems to be intimately related to a belief in presence. That it is the fact that Mary believes the memory to be real that gives it a qualia of subjective experience.
Imagine that you wake up from a dream and find yourself in a new body. You have all your current memories and you are explicitly told that those memories have been implanted within your new body. Would you be the same person? Mary’s Room seems to suggest that we would be something not just slightly different, but entirely so - that all of our memories would be stripped of the qualia that is your belief in your real presence within those memories. Would we look back on our lives with a detached, emotionless objectivity, as dreams that happened to someone else? Or would our egos merely snap under the weight of that existential pressure into a complete breakdown of identity?
Maybe, one day, when we backup ourselves into some fresh new container for our minds, we might program in a little lie for ourselves. A little illusion, a little false belief that rewrites our memories into one of continuous presence.
What's the problem? If you could show that Mary never experiences a colour quale, whether as the result of a direct experience, or a real memory, or an implanted memory, you refute the argument. But you dont seem to be showing that.
What's the problem? If Mary has a present experience of a blade of grass, she will have a novel colour quale, and she also will if she experiences a sufficiently vivid recollection... and that still applies if the memory was an implant.
Which quale, and why? Mary's Room is about colour qualia. If they don't disappear, Jackson has made his case. You might be talking about some other qualia that maybe represent "this is a novel experience" or "this is memory belongs to me"...
Hey TAG, thanks for your reply and your great points.
Well, I don't believe I'm trying to say that the color quale doesn't exist - rather that the quale is the subject's beliefs around that experience or memory, and that those beliefs are entirely physical constructs that exist within a physical brain.
This is based on an admittedly wild assumption that experiences memories that you know to not be yours would alter the quality of those experiences. The impact I think is lost when we deal with something as ubiquitious to the human experience as color. But Jackson seems to be making a general claim about all experiential qualia with this thought experiment, not a specific claim about color qualia, even if that is the example he chooses.
Maybe another example is implanting a memory of climbing Mount Everest - euphoric king-of-the-world moment included when you reach the peak. The belief around the veracity of that memory would alter your relationship to it, and you would gain some new qualia experience if you actually went and did it.
If you could show that qualia are just beliefs , that would refute Jackson. But it is not clear that you are a sceptic about the very existence of qualia, since you keep using the term "qualia".
Why does that matter? If there are any experiences or qualia, even changeable ones, Jackson has made his point.
Are you arguing that
Qualia (phenomenal states) do not exist unless they are distinct from cognitive states (beliefs, etc).
Distinct means completely distinct.
If so-called qualia can be influenced by beliefs , they are not completely distinct.
They can be influenced by beliefs
So they dont exist.
Has he? As I understand it, Jackson is arguing specifically for a non-physicalist interpretation of qualia in his work, not just for the existance of qualia. He is arguing that you can have perfect information about an experience, yet actually experiencing that thing will still bring some new aspect to the experience, and whatever that aspect is is the qualia. The issue is with the nature of what the qualia of an experience is, and whether there is a physical manifestation of it, not whether it is a thing. It obviously is, as we constantly experience it. So, no, sorry if I have come across as arguing that qualia do not exist, that is not the position I'm trying to discuss here.
You've told me what you don't think, not what you do. Why does it matter that something "would alter the quality of those experiences"?
Sorry TAG I'm not quite sure I follow, but I do appreciate your feedback. This post is a refutation of Jackson's view, so I'm not surprised that it is focusing on a negative. Whether something would alter the quality of those experiences is the crux of Jackson's whole thought experiment - asking what changes between a mind with perfect information about an experience, and a mind who has genuinely had that experience. So, that question does seem at the heart of this thought experiment.
Perhaps a different way to think about Mary's Room is the following:
You have two identical minds, A and B. You know that one mind has perfect information about an experience, and the other mind has genuinely experienced it. What questions can you ask each mind to determine which is which? Are you always able to determine an answer? Whatever pops out the end as the distinction between the perfect information and the subjective experience is, by definition, what the qualia of that experience was.
Asking or answering? Do you have an answer to the question?
Maybe not. Why does that matter?. Qualia are supposed to be subjectve, so it's not some gotcha to point out that they can't be determined objectively.
Maybe that is subjectivity itself. Maybe qualia are how observers perceive their own brain states.
I apologise TAG, I can't say I'm trying to "gotcha" anything intentionally, just to discuss an interesting thought experiment.
I don't know what the test is that you could perform, though I tried to present one possibility - your beliefs around that memory.
It matters here because I am specifically addressing Jackson's views on Physicalism as presented in the original thought experiment, not all general views of qualia. The core of the question is if that is because of some physical phenomena.
Yes, that is a good summary of what I am proposing here.
Gotchas aren't an entirely bad thing, because at least you would be making a discernable point.
I asked you directly whether you were asking or answering ...and you did not answer!
Well, I think that is technically a departure from physicalism. But you said you are a physicalist!
Well, I apologize that this has not been clear for you. I am somewhat surprised that you can so elegantly summarize my position while simultaneously saying I haven't made that position, but maybe I'm just a lot, lot worse at expressing myself than I think I am haha.
Sorry, I'm not sure what this is regarding exactly. As in, am I asking Mary questions? Yes. Or am I asking a question about the thought experiment? Also yes. Or if the thought experiment is designed to provide a question as to what qualia is, or an answer? You tell me! I think it reveals something about what qualia is, at least, as the distinction between information about a thing and subjective experience of a thing.
Why is a belief a non-physical thing? It's just a state within a system, arrangement of neurons, etc. The fact that it is a belief, and therefore something that has physical and real presence, is my whole refutation of Jackson's view that it is something immeasurable or materially unknowable.
You didn't state that position in your OP. It took a whole series of guesses to get to this point.
I didn't say anything of the kind.
If you are saying that qualia are just beliefs that is a different claim, and one that you havent supported.
Why should some, but only some beliefs, be inherently subjective?
May I clarify, when you said:
You then said that this summary was a departure from physicalism. Could you explain what you meant by that? It was that statement that made me think you were saying that a belief was non-physical, as you said qualia being a belief was a departure from physicalism.
Oh dear... I think we might be in a bit of trouble, as I'm under the impression that's pretty much the claim we've been talking about this whole time. It seems like another rephrasing of your previous summary, and exactly what I've been trying to say. The testable differences are the beliefs about that memory, and beliefs are a physical thing, so qualia don't need to be supernatural or immeasureable.
I said is that is is "technically a departure from physicalism".
I'm not talking in the usual vague terms of "physical stuff" and "mental stuff".
If physicalism is taken as the claim that everything has, or potentially has, a reductive physical explanation, it follows that everything has a mathematical description, since mathematics is the language of physics. Physics doesn't merely use numbers to represent measurements, it uses a variety of mathematical functions and structures to represent physical entities and laws. Mathematical language is the language of physics, and also the quintessential 3rd person, objective language, so physicalism, which is apparently an ontological claim, has an epistemological implication: physicalism implies reductionism implies physics implies maths implies objectivity.
Conversely, the claim that there is irreducible subjectivity is a departure from physicalism, but not in a way that means are mental entities, substances or even properties separate from physical ones. The minimal requirement to support the claim of irreducible subjectivity is that a conscious entity's insight into its own mental states has ineffable, incommunicable aspects.
That summary argument isn't valid. In order to get from the premise (1) that the only knowable differences between qualia are stateable beliefs about qualia, to the conclusion that (3) qualia actually are mere beliefs , you need (2) the assumption that qualia cannot differ in ways known only to the person who has them...which begs the question against anything being inherently subjective or incommunicable.
That's a great point! There is that possibility, but do we need to make that assumption? I'm not sure.
Mary would be able to tell us if "qualia did not differ in ways known only to the person who had them", even if she might not be able to describe to us exactly how. She'd be able to say "that was different", even if the precise words to describe how it was different escaped her, and that true/false response is enough to draw some meaningful conclusion about the existance of something, even if it doesn't tell you anything about the nature of that thing. And if it's completely imperceptable to Mary, then it can't be qualia, as qualia is by definition about subjective perception.
This whole post strikes me as extremely confused. I'm trying to put my finger on why.
Nothing. Assuming Mary can mentally visualize colors (not everyone can), then she now has access to e.g. the "redness" quale, and has that experience of redness whenever she recalls her false experience, and now has the ability to imagine red things, and when doing so will also have the experience of "redness". She can generate the "redness" quale on demand in her own mind. She may also spontaneously hallucinate red things in her dreams without trying.
This doesn't follow at all. She can visualize red things now. Suppose Mary believes those memories to be real.
Depending on how the implantation process works, that process may or may not have produced the conscious experience of "redness" in Mary.
Regardless of this choice, suppose you now tell Mary how her experience of leaving the room came about and she believes you.
Now she knows her experience was implanted. Why would you expect her to suddenly become unable to imagine something red? To stop dreaming of red things? People in dream states are not especially concerned about whether their experiences were real or not.
Mary learned something new, even from the implanted memory, that she couldn't have learned just by reading black-and-white textbooks about color perception. If you take her out of the room for the first time, she'll immediately be able to tell you which things are red just by looking at them. She wouldn't have been able to do that without the implant.
Hi gilch! I apologise that this was confusing, hopefully I can clarify what I am trying to say here. Thanks for your in-depth response.
Yes, this was the answer that was meant to be inferred here. Maybe I could have been more clear that this is the correct answer. There isn't really any question that you can perform to determine which Mary genuinely had the experience and the Mary which did not.
I think it might be useful to think about Mary's room in more abstract terms, to avoid these contextual assumptions we make about the nature of qualia like with colour. Because colour is a general qualia of existence, as opposed to a specific experience (e.g. the example given elsewhere in the comments of the qualia of climbing Mt. Everest) we have different expectations around it. I would be curious to know if the more abstracted version of Mary's Room outlined in this comment here would make this clearer.
OK, I think we agree that subjective mental states correspond to physically real states in the brain, and that Mary's Room is insufficient to refute physicalism. Was that your point/conclusion?
What I'm not understanding is your argument for getting there. Either it's not valid, or I don't understand what you mean.
I mean it was a point that I made from just playing around with the thought experiment. I don't know if it is the point, that's why I'm trying to dissect it a little here.
I would be happy to keep trying to explain. Let me try to lay it out again in a different way, and I'd be interested to hear what you think:
What questions can you ask Mary to determine these answers? When can you be confident, and when is the answer indeterminable?
A second way to think about it is if you sent Mary through the door a 2nd time, in which scenarios would Mary learn something new - and therefore experience the qualia they did not posess at the start of the experiment, despite their perfect information?
I dispute this premise. If Mary knows how to visualize something red (and learned how to do so through some means other than seeing it with her eyes) and knows that it's called "red", then that's knowledge, and she won't learn anything new by seeing it for the first time. This isn't knowledge that Mary could acquire by reading black-and-white textbooks about cone cells and neurons, but hypothetically the knowledge could be implanted in her brain via some technology while bypassing her eyes.
Mary aquires the new, novel experience of believing that she has seen the color red, when she previously held the belief that she only had perfect, but non-subjective knowledge. Qualia does not necessarily need to be new information as this attempts to demonstrate, it just is whatever is different about your mind when you actually experience a thing.
Why does that matter?
Because that test reveals what the actual qualia of the experience is - what separates all of the information about an experience from the subjective essence of that experience. The qualia of an experience is not simply the ability to recall that experience, or simulate that experience in your mind.
The experience of recalling experiences is itself an experience. The experience of imagining an experience is itself an experience. These internal mental experiences are less vivid than a direct sensory experience is in the present for most people most of the time, but sometimes dreams can be as vivid as waking life. Internal mental experiences still have qualia, and they use the same sensory channels as the direct sensory experience does. You can recall or imagine or dream about how something looks or sounds or feels like etc.
The memory doesn't have qualia except during the act of recalling it consciously.