Qualia: Mary’s Room

Please familiarize yourself with the following: Mary’s Room

Done? Okay.

The first objection to that thought experiment is that it postulates an entity with complete knowledge of an event, which logically requires complete knowledge of the entire universe. And that’s impossible from within the universe. ‘Complete scientific knowledge’ requires strong omniscience, which I am reasonably certain human beings do not have.

But let’s be generous, and presume that something far weaker was meant. What if Mary merely knew everything that the scientific method could ever reveal to us about human neurophysiology and the processes of visual perception?

Then it would be absurd to speculate what such vast knowledge would not let someone know, since it would extend far beyond our current understandings of those things. How would you know that such knowledge wouldn’t give Mary foreknowledge of color? Hmmm?

Let’s be even more generous, and limit Mary’s knowledge to what can be plausibly extrapolated from our current knowledge. Doesn’t Mary learn something new about color then?


Stimulation of the optic nerve is perceived as light and color. As are certain kinds of stimulation of the parts of the brain involved in processing vision. Presumably sufficiently precise stimulation of the parts of the brain involved with memory retrieval would result in ‘remembering’ visual experiences as well. It’s possible that memory involves the use of what are effectively pointer variables, so the ‘experience’ wouldn’t be part of the memory itself in that case, but it would involve a reference to the brain modules involved with vision.

If Mary’s knowledge were extensive enough, she could completely lack the parts of the brain specialized to deal with vision, but emulate them in non-specialized parts of her brain sufficiently flexible as to permit Turing-complete processing. Or with an electronic computer. Or by writing things on scraps of paper and shuffling them around. You get the idea.

The resulting output, when fed into the right places in Mary’s brain, would produce exactly the same result that beaming the right kinds of light into her eyes normally would.

Hell, if all she wants to do is learn about color, she could just push gently on her eyeballs. The resulting nervous stimulation from the pressure would generate all sorts of colored patterns.


23 Responses to “Qualia: Mary’s Room”

  1. I think you’ve sidestepped the problem. I agree that in the first two implausible cases, Mary knows everything about color, and so from a physicalist standpoint she even knows what red qualia feels like, if there is such a thing. However, in the last case, pushing on her eyeballs might just cause her to perceive qualia.

    So while I agree that the thought experiment is silly and doesn’t show what its originators think it shows, this analysis sadly doesn’t say anything useful about qualia.

  2. “However, in the last case, pushing on her eyeballs might just cause her to perceive qualia.”

    Which then have nothing to do with ‘redness’, and all about the nature of neural impulses?

    Do I have that straight?

  3. Right. The redness I perceive, as in the question ‘Do you see the same color I do when we look at that red ball?’, does not depend on what sort of light are being sent out by the ball.

    Note: This is a silly question, pragmatically speaking. If you’re a pragmatist, the right answer is that both sides of the debate are wrong for arguing over a question that nothing seems to turn on.

  4. Ah, but the fact that nothing turns on it indicates that the side that insists there’s something there is wrong.

    There’s nothing there.

    The experiment with mirrored goggles and direction-sensing indicates that our neurology is quite capable of deriving whatever information it needs from data, even if it’s ‘reversed’.

    I am asserting that you don’t “see any color” at all. The neural states you enter and the ones I enter need have nothing in common, save that they are stimulated by certain inputs and are responded to appropriately.

    Does it make any difference to the program if all of the ones are shifted to zeroes, and vice versa?

  5. Mary’s room is indeed an extremely weak thought experiment for the non physical. It doesn’t even do a good job of tapping into an intuition that makes us question better rational judgement. It’s fairly trivial to remove the non-physical by thinking “Even if Mary experiences red as never before, it was only because it activated neural wiring in her brain that can only be activated by certain wavelengths of light.”

    In other words, knowing all there is to know about red is impossible because the wavelengths of red can be interpreted in an infinite number of ways since there are unlimited mechanical configurations which can interpret red light. So Mary ‘learning something new’ with a colored TV set is expected when you introduce new information into the equation (colored TV), and actually confirms the physical. I believe you covered this general line of attack here in the first paragraph.

  6. The “thought experiment” has actually been performed, philosophers are just too airy to realize it. Restore the senses of congenitally blind/deaf people and their brains will be incapable of interpreting the new information. They also get severely depressed, which is even more sad. Past a certain point there’s not much chance of the brain developing if it hasn’t already.

  7. With the general loss of neural flexibility at puberty (and possibly the passing of a window of development), the brain no longer can process incoming signals and generate associations between them and existing states.

    But let’s say that Mary has been magically generated with a ‘normal’ brain even if her life experiences wouldn’t have permitted that kind of development.

    I will note, however, that the inability of the formerly blind-from-birth to see properly suggests that there are no ‘universal’ qualia shared between people, as the response to visual stimulus needs to develop in each person and probably does so uniquely.

    If we descend to postulating unique qualia for each individual, then there’s really absolutely no difference between that and simply abolishing the idea.

  8. P, the thought experiment has not been performed – name one omniscient person who was blind from birth and had his sight restored.

    melendwyr, if I have the best ham sandwich in the world, and I never have another ham sandwich, and nobody else will ever have a ham sandwich like the one I have, then that doesn’t entail that there’s no point in me eating it. It might give you no reason to think that my ham sandwich is awesome, and I might have no reason to think that my ham sandwich is particularly awesome, but those facts are independent of the awesomeness of eating this particular ham sandwich.

    Unique qualia for each individual might give us no reason to talk about qualia, but that wouldn’t entail that nobody experiences qualia. But then, there also would be no reason to have the idea ‘qualia’, which I think is what you said anyway.

  9. “P, the thought experiment has not been performed”

    True, but missing the point.

    A similar, more-inclusive thought experiment has been performed,and its results are not compatible with even weak qualia.

    If everyone had unique qualia, there would be no point in discussing “the redness of red” because there would be no shared properties to refer to, no ‘redness’ to talk about.

    If you don’t mind my asking, Thom:

    In your use of the term ‘qualia’, do you mean anything beyond “the associations that recognizing a state has that cannot be derived from the state itself”?

  10. Maybe. I take ‘qualia’ to refer to ‘what it’s like, subjectively’ to experience something. I disagree that there can be some nonphysical thingy involved, but I think the term is clearly meaningful and one should not be eliminitavist about it. To take the Wittgensteinian route, the experience of redness is more apparent to me than any arguments I might think of for its non-existence, and the name for that experience is ‘qualia’. I don’t think this is a grave misuse of the term, based on my understanding of contemporary epistemology / philosophy of mind.

  11. “I take ‘qualia’ to refer to ‘what it’s like, subjectively’ to experience something.”

    That’s not very useful.

    “I think the term is clearly meaningful”

    I am very suspicious of this claim. I think we have a very strong intuition that it is meaningful, and that the intuition is wrong, in the same way that we intuitively believe our visual experience is continuous while it actually occurs in discrete ‘flashes’.

    Can you decompose your ‘experience of redness’ at all, conceptually?

  12. No, I think inventing useful concepts to describe what things feel like would be a time-consuming task. As I mentioned in an earlier comment, subjective experiences are really hard to get a handle on in terms of anything else.

    To say that our visual experience ‘actually’ occurs in discrete flashes is, I think, mistaken. The continuous nature of the experience is obvious. That most of that experience is an invention of the bran is irrelevant, as we’re talking about ‘experience’, which I take to be defined by what it seems like to the experiencer.

    I think denying our most basic intuitions is pointless; everything else is built upon them. We start from where we are.

  13. It’s nice to converse with people worth arguing with.

    Thank you for that, at least, Thom Blake.

    “To say that our visual experience ‘actually’ occurs in discrete flashes is, I think, mistaken.”

    Oh, no. The Spinning Wheel illusion elegantly demonstrates that’s not the case. it can be seen most easily on film, which is where most first encounter it, but at higher speeds the illusion arises from bare eyes alone.

    Regarding qualia and our basic intuitions, we may have to agree to disagree. Or fight with knives. Either one.

  14. Thom, it has been performed. It’s just been performed without the magicical wand waving alla-kazam! that philosophers would demand. Consider how much simpler the actual experiment was, in comparison with the thought experiment (showing, incidentally, that not much thought went into the latter).

    A lot of Einstein’s abstract thought experiments were never actually performed either. Real experiments were performed which proved the same thing though.

  15. P, I think we’re climbing the same hill from opposite sides. When the physicalist sees that thought experiment, the obvious conclusion is that Mary wouldn’t be surprised whatsoever when she leaves the room, because she already knows exactly what to expect, by hypothesis. Your version abandons the thought experiment entirely and notes that Mary’s brain would be undeveloped for experiencing color at all. (note that this is what Mary the color scientist should expect to happen if it’s the case)

    Melendwyr, I seldom accept that ‘agreeing to disagree’ is an acceptable solution, but I’m already half-convinced you’re a robot, so I have no interest in fighting with knives. It might not be fair if you maybe don’t experience pain the same way I do.

  16. “I’m already half-convinced you’re a robot”

    A robot — made of MEAT!

  17. “Oh, no. The Spinning Wheel illusion elegantly demonstrates that’s not the case. it can be seen most easily on film, which is where most first encounter it, but at higher speeds the illusion arises from bare eyes alone.”

    How can our visual experience consist of discrete flashes when we don’t in fact experience these flashes? If we experience them from some illusion, then that is only temporary and probably resulting from some low-level mechanical bug or interface exposure that gets activated with certain stimuli. Even if our low-level visual system updates only periodically, our higher level cognitive functions can combine that information into a seamless experience.

  18. No, they can’t.

    A continuous stream can be turned into a discrete one by discarding / ignoring information, but the reverse is not possible except by ‘inventing’ data and ‘filling in the blanks’.

    Our data is discrete, but we intuitively believe it to be continuous. This is a delusion created by the basic modules of visual processing, an illusion.

  19. Are we just arguing over semantics here?

    “Our visual experience is made up of discrete flashes.”

    Could mean:

    1.) Our experience (what we are 100% sure of, as opposed to mechanical low-level stuff which we aren’t, and have to guess at with science) actually contains updates in discrete flashes. To the point where we can say “there’s an update! There’s another!”. This would also cause many of us to complain to our doctors: “Why the heck is the world constantly interrupted by blackouts/pauses/whatever? What’s wrong with me?”

    2.) Our experience (which has no flashes) is mechanically produced by discrete visual data updates which we are not aware of and had to learn about through scientific observation.

    Right now I’m thinking you believe 1. Perhaps that’s what’s wrong.

  20. You are incorrect.

    Perhaps this rephrasing will help:

    Our low-level experience of the visual world is broken up into sections. Our high-level understanding of that experience insists that it is continuous.

    Our intuition about how our vision works is fundamentally wrong. Our meta-awareness is incorrect.

  21. Here’s an alternate way of explaining it:

    The visual world is continuous. Our low-level experience is broken up into sections, which are then recreated into an ‘illusory’ continuous experience to better approximate reality.

  22. Ok, but if your using ‘experience’ to describe things that people generally wouldn’t say they are away of, like low-level visual updates, then you aren’t describing conscious awareness, but cognition in general, and we are talking about two different things completely. Perhaps your argument is that there is no division between ‘awareness’ and ‘all cognition’, as it would be nonphysical for our awareness to be different from a full reductionist description of what happens inside the brain?

  23. It’s not clear that we can speak of this illusion having a purpose.

    If the visual-processing modules work slowly enough that they can’t keep pace with the flashes of visual data, the illusion of continuity might arise directly from that, without evolution having selected for any particular delusion.

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