Mary’s Room

Philosophy is chock-full of fantastical thought experiments. Sometimes, though, the scenario we’re asked to imagine is so fantastical that it undermines the point of the experiment. From my perspective, the “Mary’s Room” experiment is one such.

This thought experiment was proposed by Frank Jackson in 1982, though the basic idea for it has a far longer history. It is meant to cast doubt on materialist understandings of the mind. Here’s the essence of it, as presented by Daniel Dennett (quoting Jackson) in his book Intuition Pumps and Other Tools for Thinking:

Mary is a brilliant scientist who is, for whatever reason, forced to investigate the world from a black and white room via a black and white monitor. She specializes in the neurophysiology of vision and acquires, let us suppose, all the physical information there is to obtain about what goes on when we see ripe tomatoes, or the sky, and use terms like “red”, “blue”, and so on. She discovers, for example, just which wavelength combinations from the sky stimulate the retina, and exactly how this produces via the central nervous system the contraction of the vocal chords and expulsion of air from the lungs that results in the uttering of the sentence “The sky is blue”. (It can hardly be denied that is in principle possible to obtain all the physical information from black and white television, otherwise the Open University would of necessity need to use color television.) What will happen when Mary is released from her black and white room or is given a color television monitor? Will she learn anything or not? It seems just obvious that she will learn something about the world and our visual experience of it. But then it is inescapable that her previous knowledge was incomplete. But she had all the physical information. Ergo there is more to have than that, and Physicalism [i.e., materialism, the denial of dualism] is false.

My knee-jerk reaction is precisely the one Jackson wants me to have. Of course Mary learns something new upon encountering color for the first time. What it feels like to experience color is just obviously not something you can know from a catalog of physical facts. Right? Sometimes, though, knee-jerk reactions need to be resisted.

This particular experiment has attracted quite a voluminous literature. The ever-useful Wikipedia has a nice summary, and the Stanford Encyclopedia of philosophy provides more detail still. There is rather a lot of thrust and parry, much of it fascinating and ingenious.

It’s just that the more I think about it, the more I think that the scenario I’m being asked to imagine is just too bizarre to clarify much of anything. Complete knowledge of every possible physical fact related to color vision is something we are so far from having that I do not know how to imagine what it would be like to have it. Perhaps the possession of so much physical knowledge simply entails also knowing everything about the sensation of experiencing color. If that seems bizarre or implausible, it is only because the scenario itself is bizarre and implausible.

Dennett makes a similar point in Intuition Pumps:

All the physical information there is to obtain? How much is that? Is that like having all the money in the world? What would that be like? It’s not easy to imagine, and nothing less than all will serve to make the thought experiment’s intended point. It must include all the information about all the variation in responses in all the brains, including her own, especially including all the emotional or affective reactions to all the colors under all conditions. So she will know in exquisite detail which colors calm her, annoy her, would grow on her with exposure, distract her, repel her, and so on. Is she forbidden to perform experiments on herself (without cheating, without smuggling any colored things into her cell)? If you didn’t imagine all this (and more), you didn’t follow directions.

…If Jackson had stipulated that Mary had the God-like property of being “physically omniscient”–not just about color but about every physical fact at every level from the quark to the galaxy–many if not all readers would resist, saying that imagining such a feat is just too fantastical to take seriously. But stipulating that Mary knows merely all the physical facts about color vision is not substantially less fantastical.

Well said!

As I have written before, I find it very hard to understand how entirely physical processes within the brain can give rise to consciousness and subjective experience. I regard it as the most likely explanation, however, because everything we have learned from cognitive science and neuroscience points strongly to that conclusion. Moreover, I can see the many practical benefits of taking a physicalist view of mind; the success of drug therapies in combating mood disorders is one obvious example. This all strikes me as strong evidence for physicalism, to the point where something more than armchair philosophy will be required to make me abandon it.

When someone finds a way to turn non-physical theories of mind to practical advantage I will take them more seriously. Go treat an illness, or make someone’s life measurably better by tending to the non-physical side of their minds. That would be impressive. But as long as such theories amount to hand-waving, or worse, as gateways for a variety of New-Agey, spiritualist or religious ideas, I think I will continue to scoff.

To wrap this up on a grandiose note, I see a tenuous analogy here with the cosmological argument for God’s existence. My main problem with the Mary’s room experiment is that I am being asked to imagine something so far removed from actual experience that I have no reliable intuition to fall back on. I have a similar problem with cosmological arguments, in their various forms. They generally rely on using categories we find useful for organizing phenomena in our daily lives–like cause/effect or necessity/contingency–and then extrapolating them to assertions about the origins of the universe. Even without getting into the often byzantine details, it is hard to see how any argument of that general form could possibly be convincing. We know nothing at all about what brings universes into being, and we have no basis for thinking that intuitions useful in daily life retain any value in pondering the origins of everything.

And when you factor in what I take to be the many good reasons for thinking there is no designing intelligence to the universe, it will take more than philosophy can offer to make me convert to theism!

Comments

  1. #1 Physicalist
    http://physicalism.wordpress.com/
    December 10, 2013

    Overall I agree that our intuitions in these cases are frequently misleading, but clever people like Dennett can help show us our mistakes.

    I will say that I see value in trying to make sense of the world even if it can’t be translated into some “practical advantage.” Discovering what goes on at the center of black holes is unlikely to offer many practical advantages, but it’s still worth figuring out, if we can.

    (By the way, the name is Frank Jackson, not “Johnson”.)

  2. #2 MNb
    December 10, 2013

    “the scenario I’m being asked to imagine is just too bizarre to clarify much of anything. ”
    While that’s correct there are less bizarre scenario’s conceivable which make exactly the same point, but only less clear. You can think of someone born deaf and regaining hearing capability by means of surgeon or something.

    “Will she learn anything or not?”
    As so often in this kind of problems it depends on ambiguity of language. Could you please define “learn” first? If this includes experience, ie empiry, than Mary’s knowledge by definition was incomplete. If it excludes experience than she didn’t learn something.
    So I really don’t see how this affects materialism. It rather confirms a point made by Bertrand Russell long ago, when he still was a logical positivist: a lot of problems disappear as soon as we use well defined terminology.

  3. #3 MNb
    December 10, 2013

    ” I find it very hard to understand how entirely physical processes within the brain can give rise to consciousness and subjective experience.”
    Well, physicists up to today find it very hard to understand how superconductivity at relative high temperatures is possible. Are we going to conclude any woo from this problem?

  4. #4 jane
    December 10, 2013

    “Go treat an illness, or make someone’s life measurably better by tending to the non-physical side of their minds. That would be impressive. ”
    I would think that studies showing benefits associated with meditation would fall into this category – as would studies that “combat mood disorders” by non-drug therapies, and especially talk therapy.

  5. #5 Jason Rosenhouse
    December 10, 2013

    Physicalist–

    Thanks for pointing out the error, which I have now corrected.

    jane–

    What’s the non-physical theory of mind underlying the success of meditation and talk therapy? A materialist would argue that our personalities and emotions arise ultimately from physical interactions within our brain, but that doesn’t mean that some mental issues should not be treated at a higher level. It’s like saying that we don’t repair a car by manipulating individual atoms.

  6. #6 sean samis
    December 10, 2013

    Jason, this is a nice post. I am not aware of anything verifiable that a non-physicalist theory adds to our knowledge.

    And your closing comments on “cosmological arguments” are sound. Theists who employ such arguments are—whether they know it or not—are endorsing a kind of nature-worship. For Christians this is an incoherent if not heretical position; yet it is not a rare belief. They may as well worship a tree.

    sean s.

  7. #7 G
    California USA
    December 10, 2013

    “If we had complete knowledge of visual perception, then (blah blah)” is hardly as extreme a claim as “If we had complete knowledge of starting conditions at the Big Bang, then we could predict every subsequent event in the universe.” So why should we allow hard determinists to get away with the latter? Do we give them an exception to Heisenberg along the way?

    A more useful example than Mary’s room, would be any instance of the neurochemistry of emotion, for example dopamine and pleasure. We can describe in detail how dopamine interacts with neurons, but those descriptions are not identical with the subjective experience of the quality of pleasure associated with dopamine release. Someone engaged in research on that subject could very well benefit from having the first-person experience, by way of learning something about it that leads to further testable hypotheses.

    However all such cases are only restatements of the underlying issue that objective data are different to subjective experience or “qualia”, which in turn point back to the hard problem of consciousness itself that remains a puzzle.

    The term “nonphysical” is effectively meaningless. Whether consciousness turns out to be _produced by_ the brain, or _transduced by_ the brain, it will still have a basis in some kind of natural phenomena whether currently known or currently unknown.

    Meditation does not presuppose or infer any particular theory of consciousness. We know quite a bit about what goes on in the brains of people who are meditating: much of this research goes back to the late 1960s and 1970s.

    We can also run that relationship in reverse, as it were, by providing individuals with stimuli that induce subjective states that are highly similar to those induced by conventional meditation exercises. Auditory entrainment of EEG is well established in the literature, and can be replicated easily. For anyone who wants to play around with this, keyword search “Gnaural” for an open-source app to generate entrainment tones on your computer.

    But, “surprise!,” that’s precisely an example that comes from a “nonphysical” theory of mind: it was first discovered by researchers at the Monroe Institute who were seeking to find ways to reliably induce out-of-body experiences under controlled conditions.

    The moral of that story is twofold:

    One, honest researchers in “paranormal” or “transpersonal” subject matter often end up with results that support strong brain/mind theories of consciousness.

    Two, honest rationalists ought to be willing to give credit where due, even when that means acknowledging the contributions of those whose paradigms differ substantially from their own. (See also Martin Luther King: it’s OK to admit that religion isn’t all bad.)

    Any presumed relationship between theory of consciousness and theology is nonsense. What I find most puzzling is how rationalists can reject religious & scriptural claims altogether, but then swallow without question two in particular:

    One, that the hypothetical existence of an immaterial aspect of mind is inferential proof of the existence of a deity (it is not). Two, that free will is proof of creation by a deity (it is not). (Claims by atheists, for the nonexistence of free will, necessarily assume that the theological interpretation of free will is correct. And the moral of that story is, be careful what you swallow, it may bite you back.)

  8. #8 AnswersInGenitals
    December 10, 2013

    JR, you left out the most important part of the experiment. Later that day neurosurgeon Marvin Schweitzkopf (of african descent and wearing a white lab coat to keep with the room’s color scheme) enters the room and performs brain surgery on Mary while she is fully conscious. (Brain suregery is frequently performed on fully conscious subjects since the brain has no pain sensors and this allows the surgeon to identify specific functional areas of the brain.) While Marvin probes Mar’s brain with various needles and electrical probes, Mary experiences a variety of sensations including tastes, smells, and colors. She even experiences the color red even though there are no red wavelength photons in the room. Such mechanical and electrical stimulation not only elicits sensations, they also elicit emotions, memories, and muscle responses. What could be more definitive proof that the mind is purely physical and physically explicable? There have even been occasions when subjects/patients experienced sensations or emotions that they could not describe because they had never felt them before.

  9. #9 MNb
    December 10, 2013

    “Any presumed relationship between theory of consciousness and theology is nonsense. ”
    Even if we for the sake of argument accept that it can make sense lots of theology can be put into the dustbin:

    http://ngm.nationalgeographic.com/2007/07/swarms/miller-text

    Looks like something like collective consciousness exists, if it’s a meaningful concept.

  10. #10 eric
    December 10, 2013

    all such cases are only restatements of the underlying issue that objective data are different to subjective experience or “qualia”, which in turn point back to the hard problem of consciousness itself that remains a puzzle.

    I’m not sure that the Mary’s Room example is “the hard problem of consciousness” though. I think MNb has a good point: if you define understanding as including empiry, then by definition Mary doesn’t start with a complete understanding. OTOH if you define understanding as excluding empiry, then walking outside doesn’t increase her understanding. Either way, the Mary’s Room puzzle really just amounts to a question of definitions and terminology. The “problem” it presents only exists if we use the word “understanding” inconsistently, to exclude empiry while she’s in the room but include it when she leaves the room.

  11. #11 Another Matt
    December 10, 2013

    “Knowing all the physical facts” is famously sticky. There’s some debate, for instance, about whether Laplace’s Demon would be able to make out objects at levels of organization approaching human scales. Can it “see” or “know about” elephants? Or “just particles?” You have to stipulate up front which version of the demon you are positing because the different assumptions lead to totally different conclusions and confusions.

    As for Mary; Dennett likes to point out that Mary would likely be able to name all the colors correctly the first time she sees them. How does that change the intuitions one might have about this thought experiment?

  12. #12 Richard Wein
    December 11, 2013

    Others have made similar points, but I’ll add my twopenceworth.

    “My knee-jerk reaction is precisely the one Jackson wants me to have.”

    I don’t think I had that reaction, because I’ve had enough experience with such metaphysical arguments to be extremely skeptical. For me, they fail the smell test. I try not to allow myself to be carried along by the superficial appeal of the argument, but immediately start looking out for the linguistic confusion which is always to be found. As Wittgenstein famously said, philosophy is a battle against the bewitchment of our intellect by our language. Makers of metaphysical arguments like this one seem oblivious to that battle.

    “It’s just that the more I think about it, the more I think that the scenario I’m being asked to imagine is just too bizarre to clarify much of anything.”

    It’s not just bizarre. It’s extremely ill-defined. What does it mean to “acquire all the physical information there is to obtain”? What is “physical information” and how does it differ from non-physical information? The argument makes no attempt to clarify. When Mary sees a blue object for the first time, she probably acquires some memory of the experience. I suppose we can call that “acquiring information”. But what does it mean to ask whether this information is physical or not? If the arguer thinks that Mary acquires something more than I’ve described, then the onus is on him to argue that.

    Let’s say we expose a computer with a camera to a blue object for the first time, and it records a colour video of the blue object. That computer has acquired information. But we don’t think anything of it. We don’t wonder whether this is physical or non-physical information. The question seems either meaningless or trivial. If we say it’s physical because the video data is stored in physical memory, then why shouldn’t we say the same about Mary? If we say it’s physical because it’s a recording (memory) of a physical object, then why shouldn’t we say the same about Mary? If these are not the sorts of things that the arguer means by “physical information”, then the onus is on him to make his meaning clearer.

    The argument does not address such meaningful questions as “What change of state occurs when Mary sees blue for the first time?” and “Can this state be caused by a physical process?” Instead it uses vague language that we can’t make any real sense of, but which has just enough superficial appearance of sense to look like a meaningful argument.

  13. #13 eric
    December 11, 2013

    The argument does not address such meaningful questions as “What change of state occurs when Mary sees blue for the first time?” and “Can this state be caused by a physical process?”

    In this toy example, her cones have never undergone activation. They’ve never fired and thus never sent signals to the brain, which has never processed any signals from cones. Which means the brain may have never developed pathways to interpret such signals.

    IANAB but I have to think that these are fairly significant biological and neurological changes of state. Not activating any cones until one is an adult capable of carrying out the experiment would probably have all sorts of developmental repercussions. It would literally change the way your brain interprets color. This would lead me to a few tentative conclusions:

    (1) When Mary walks out of the room, she may not see what the rest of us see. “Seeing” is as much brain interpretation as it is chemical reactions in the eye, and Mary’s brain may not be capable of interpreting the latter. Who knows what it will do. Throw the data out? Interpret colors as shades of gray? Synthesia (i.e., co-opt pathways used by other senses)? Build new pathways slowly over time? So whatever Mary gains, it is probably not an understanding of what the rest of us mean when we say ‘blue.’

    (2) Whether empiry is data or not, it is certainly a prerequisite for some types of understanding. You will not understand how your brain processes a signal from a blue cone until it processes a signal from a blue cone. This is especially true given that every brain is somewhat unique – she cannot simply look up in a textbook that neuron #510334 activates when blue cone #43333 fires, because AIUI, no such deterministic relationship exists. Some neuron will respond and form a pathway the first time the cone fires, but which one is not predictable. To me, this says that empiry is a type of data. Which resolves the room problem: the room cannot give her “all the physical information,” and the “Mary’s Room problem” stems from a faulty premise.

    (3) Even for such a hypothetical toy problem, we run into trouble if we try to do ‘pure’ philosophy and exclude what other disciplines (here, biology) tell us. Other fields matter; and this is another case where information from another field informs, partially solves, or perhaps entirely solves a philosophical problem.

  14. #14 sean samis
    December 11, 2013

    With regards to the “Mary’s Room” problem, when Mary is first exposed to colors, she will acquire two kinds of new information.

    1. Accepting the givens of the problem before Mary’s first exposure to color, let’s refer to all she knows about color as her academic information and that it is as complete as the problem poses.

    2. Suppose Mary’s first exposure to color is when she is given a set of color swatches. Mary now acquires new information: primary sensory information of color. The parts of Mary’s brain which respond to color stimuli will be put to that use for the very first time.

    However:

    3. If the color swatches are unlabeled, Mary would not know which color is which; she’s never seen them before.

    4. If the color swatches are mislabeled, Mary would not be able to detect that; she’s never seen them before.

    5. If Mary is told the swatches are mislabeled, Mary would not be able to correct them; she’s never seen them before.

    6. If the swatches are correctly labeled, Mary acquires new information: labeling information which enables Mary to connect her primary sensory information of color to her academic information about color.

    Please notice that recourse to any non-physical mind is neither necessary nor helpful to this solution.

    sean s.

  15. #15 Another Matt
    December 11, 2013

    As far as I’m concerned, eric is right on here, but I’d like to pursue sean samis’s line of thought.

    According to the problem, Mary knows all the physical information about color vision. We’re not clear at all about what that means; does it mean she knows all the physical facts about her own color vision? It could be construed to mean that she knows all the physical facts about the color vision of everyone who has ever lived. If it’s either of the latter two, Mary’s extraordinary intimacy with the workings of her own visual system does not make it at all clear that she would not be able to label all the color swatches correctly.

    Dennett’s “alternate ending” to Jackson’s story is worth taking seriously:

    And so, one day, Mary’s captors decided it was time for her to see colors. As a trick, they prepared a bright blue banana to present as her first color experience ever. Mary took one look at it and said “Hey! You tried to trick me! Bananas are yellow, but this one is blue!” Her captors were dumfounded. How did she do it? “Simple,” she replied. “You have to remember that I know everything—absolutely everything—that could ever be known about the physical causes and effects of color vision. So of course before you brought the banana in, I had already written down, in exquisite detail, exactly what physical impression a yellow object or a blue object (or a green object, etc.) would have on my nervous system. So I already knew exactly what thoughts I would have (because, after all, the ‘mere disposition’ to think about this or that is not one of your famous qualia, is it?). I was not in the slightest surprised by my experience of blue (what surprised me was that you would try such a second-rate trick on me). I realize it is hard for you to imagine that I could know so much about my reactive dispositions that the way blue affected me came as no surprise. Of course it’s hard for you to imagine. It’s hard for anyone to imagine the consequences of someone knowing absolutely everything physical about anything!”

  16. #16 Pierce R. Butler
    December 12, 2013

    Mary sounds like she would feel right at home in Plato’s cave.

    We know nothing at all about what brings universes into being…

    But we have a very clear concept, with countless examples, of what brings gods into being.

  17. #17 sean samis
    December 13, 2013

    Another Matt,

    The flaw in your argument (and Dennett’s) is that human beings don’t know “academically” what part of their brain is being stimulated by some sensory information. If we did, neurology would be far more advanced!

    Unless Mary puts herself in a brain scanner of some sort (PET in this instance?) she does not know whether the region of the brain responding to blue stimuli has been stimulated by seeing a swatch/banana, or whether it’s the “red region”.

    Mary could alternatively use some device to measure the color frequencies reflected by a swatch/banana and determine the color that way.

    But either one of these methods (brain scan or color frequency measurement) are merely another way of acquiring the labeling information which Mary cannot have until she actually sees a color. Until she analyses her response or the light reflected by the swatch/banana, she does not know what color she is seeing.

    Unless Mary is an extraordinary person, all she knows is that she’s seeing something she’s never seen before. So a blue banana would not seem wrong to her; only unfamiliar.

    sean s.

  18. #18 Another Matt
    December 13, 2013

    The flaw in your argument (and Dennett’s) is that human beings don’t know “academically” what part of their brain is being stimulated by some sensory information. If we did, neurology would be far more advanced!

    According to the thought experiment, neurology is far more advanced, at least for Mary. It really hinges on whether she knows all the physical facts about her own color vision. If she does, it would seem to imply that she knows in the most exquisite detail all of her subtle dispositions with respect to color. For instance suppose she knows that 90% of the time, if the ambient temperature is 68 degrees F and she has been awake for more than 3 hours and has not had caffeine, then a swatch of blue reduces her pulse rate by .05% but a blue banana raises it .1%. Suppose the latter always causes a slight change in the tension of her eyebrow muscles. These are all physical facts about color vision she would know about, and she would also know all of the neural correlates and the extraordinarily complex chain of causation and inhibition that brings it about. Does this change one’s intuition about the problem?

    This points to some other problems with the assumptions in the thought experiment. It’s not clear, for instance, that it is possible to disassociate color from shape when accounting for all the physical facts; the fact that someone might react differently to the color of a pumpkin when it occurs in a house fire is a relevant fact about color vision, and all of that would have to be accounted for in the physical facts. Another famous problem with color vision is the lighting problem — identical shades are perceived differently in different light because our visual system compares colors in context. Which brings up all sorts of other things that Mary knows about according to the thought experiment — she knows how every color combination in every possible shape affects the processing of “the” visual apparatus in extreme detail, on any scale from PET to subatomic. This seems infinite, but it isn’t, assuming that the human visual scene can be pixelated at some fine enough scale and color of each pixel can be varied at a fine enough scale (32-bit?). Then it would “just” be a matter of knowing in perfect detail how every possible combination of colored pixels would affect the color vision. What makes it closer to infinite is how color vision is affected by other cues like temperature, hunger, sound, mood, genetic, perceptive, or cognitive anomalies (Asperger’s, synesthesia, etc.). There are physical facts underlying how the brain processes all of this, how it ignores some cues and not others, etc.

    There’s a good case to be made that knowing all the physical facts about color vision would in fact let Mary know exactly what her thoughts would be if she were shown a yellow banana or a blue banana in any external context you please (perhaps there is a war going on outside, or perhaps the lab is under the sea or on the top of a mountain), and all of this ahead of time. Mary is indeed an extraordinary person.

    This leads to a huge problem for the epistemology of empiricism: when does a disposition count as a fact? Only when it is actualized? I haven’t learned French yet, but I’m adept with language and I’m quite certain I am able to. If I die tomorrow, did I have the ability to learn French or not? Would my death render my belief about my ability to learn French false?

  19. #19 sean samis
    December 13, 2013

    Another Matt,

    We can go ahead and assume Mary is an alien, or a God; that makes the problem moot because the question is really whether OUR minds are purely physical phenomena or not. Whether some God or some hypothetical alien has a purely physical mind or not has to wait until we meet them.

    Mary might know “how every color combination in every possible shape affects the processing of ‘the’ visual apparatus in extreme detail, on any scale from PET to subatomic” BUT she can only know how these things affected others; she cannot know how they will affect her specifically until after her first exposure, and during that first exposure she can only determine their affects after she gains new information: something or someone has to tell her what color she’s seeing for the first time.

    As for Mary’s “subtle dispositions with respect to color”, those cannot be known in advance of Mary’s first exposure to them unless we assume that every human’s “subtle dispositions with respect to color” are exactly the same. Since that is unlikely, Mary’s “subtle dispositions with respect to color” cannot be known without being observed, which is impossible prior to her first exposure.

    Further: we don’t know to what extent a person’s “subtle dispositions with respect to color” are learned; to that extent Mary’s “subtle dispositions with respect to color” are quite unpredictable because she’s not learned anything about colors until she experiences them. Mary cannot know that “a swatch of blue reduces her pulse rate by .05% but a blue banana raises it .1%” until she’s actually seen these several times. If we assume Mary has some other, superhuman way of learning facts then the significance of the problem is destroyed.

    If you are able to learn French, then the existence of that ability is real whether you ever learn it or not. If you die before learning whether you have that ability, the only thing that could have been but never actually was is your Knowledge whether you could learn French. The ability is what it is, your knowledge of the ability is another thing entirely.

    sean s.

  20. #20 Another Matt
    December 13, 2013

    As for Mary’s “subtle dispositions with respect to color”, those cannot be known in advance of Mary’s first exposure to them unless we assume that every human’s “subtle dispositions with respect to color” are exactly the same. Since that is unlikely, Mary’s “subtle dispositions with respect to color” cannot be known without being observed, which is impossible prior to her first exposure.

    I think I agree with this in general if we are talking about how humans usually do science. But in this case, she’s missing some of the physical facts about color vision. Here’s what the original actually says:

    She specializes in the neurophysiology of vision and acquires, let us suppose, all the physical information there is to obtain about what goes on when we see ripe tomatoes, or the sky, and use terms like “red”, “blue”, and so on. She discovers, for example, just which wavelength combinations from the sky stimulate the retina, and exactly how this produces via the central nervous system the contraction of the vocal chords and expulsion of air from the lungs that results in the uttering of the sentence “The sky is blue”.

    One problem is that the wording of the experiment, by using “the retina” and “the central nervous system”, is assuming that every human’s dispositions and internal workings are the same. If that’s not true then she doesn’t have all the physical information unless she knows the workings of every human visual system and brain from the subatomic to the anatomical level, including her own. I think that if you want to play by the rules of the experiment, she has to have the ability to predict, through raw physical causation, what the most likely outcome of any given visual stimulus would be for any individual. And she has to have a way to update all this information in real time, since physical (physiological, biological) states change rapidly.

    I agree that it’s a lot more interesting to rework the problem by saying, “Mary has all the physical information that is possible for a human to obtain in one lifetime.” But that defeats the purpose of the original thought experiment, which is to show that qualia are impossible to explain in principle from within materialism. The rewording turns the original metaphysical problem into a new epistemological problem.

  21. #21 MNb
    December 14, 2013

    “If that’s not true then she doesn’t have all the physical information”
    The way I interpret this is like having all the physical information about sound above 20 000 Hz (which humans can’t hear, but dogs and bats can) without having the actual experience.
    I never thought the qualia issue really through as I don’t find it particular interesting (that might change in the future). But I do know that whether they are impossible to explain in principle within materialism or not, if we don’t separate theory and empiry properly we’ll never have a good answer. That applies to “all the physical information” as well.
    So I propose to rephrase the thought experiment: during your entire life you’ve never heard any sound above 20 000 Hz. You have devoted your study to the biology and physics of sound and hearing. Now by means of some advanced surgery you receive the hearing abilities of a dog. What’s your conclusion?

  22. #22 sean samis
    December 14, 2013

    Another Matt

    When the original problem says Mary knows how sensory stimuli affects “the retina” or “the central nervous system” the only reasonable way to interpret that is that Mary knows how these things typically occur, and perhaps she has a solid grasp of the statistical variation.

    That is all well and good, but it still leaves Mary without three pieces if information:

    1: how will Mary’s retina and central nervous system respond to the stimuli?,
    2: at the precise moment of observation, how are Mary’s retina and central nervous system actually responding to the stimuli? and
    3: what color is Mary actually observing?

    Your proposed change—limiting Mary’s knowledge to what can be learned in a single lifetime—makes no difference; no amount of preparation will answer these questions because the answers have never been observed before BY ANYONE, much less Mary.

    Qualia can be explained from within materialism; it is just how the material brain responds to stimuli. I agree that this explanation is incomplete; as long as our knowledge is incomplete (which it always will be) all explanations will be incomplete.

    Non-physicalist explanations require belief in non-physical phenomena that have not and probably cannot be observed, and then those explanations fail to even answer the questions that prompted their formulation in the first place. The only value non-physical explanations have is that they give academics something to write about.

    sean s.

  23. #23 sean samis
    December 14, 2013

    MNb;

    Regarding,

    during your entire life you’ve never heard any sound above 20 000 Hz. You have devoted your study to the biology and physics of sound and hearing. Now by means of some advanced surgery you receive the hearing abilities of a dog. What’s your conclusion?

    My conclusion follows from my previous comments: you will learn something new. It might not be a huge discovery, but however small, it will be something new, something your purely material brain has never experienced before.

    sean s.

  24. #24 Another Matt
    December 14, 2013

    sean samis:

    When the original problem says Mary knows how sensory stimuli affects “the retina” or “the central nervous system” the only reasonable way to interpret that is that Mary knows how these things typically occur, and perhaps she has a solid grasp of the statistical variation.

    Yes, this is a good, reasonable interpretation, but I don’t think it’s the only one. The original problem goes on to state: “But then it is inescapable that her previous knowledge was incomplete. But she had all the physical information.” This makes it sound as though she was omniscient with regard to all the relevant facts (i.e. about everyone), not just facts about the typical situation and statistical variation. I think it’s just a badly written thought experiment because he leaves these things unclear. It would be easy enough to rewrite it along the lines of your interpretation or mine and discuss them separately.

    However,

    That is all well and good, but it still leaves Mary without three pieces if information:

    1: how will Mary’s retina and central nervous system respond to the stimuli?,
    2: at the precise moment of observation, how are Mary’s retina and central nervous system actually responding to the stimuli? and
    3: what color is Mary actually observing?

    Your proposed change—limiting Mary’s knowledge to what can be learned in a single lifetime—makes no difference; no amount of preparation will answer these questions because the answers have never been observed before BY ANYONE, much less Mary.

    And this is why we need to rewrite the problem according to our different interpretations. It is also why I brought up the question of whether there can be facts that have not yet been observed — can dispositional statements or future-tense counterfactuals be facts? I think so — it’s safe to say “if a hydrogen bomb were to explode over Manhattan, millions of people would die, provided there was no evacuation prior to the explosion” even though nobody has actually observed it. We’d have to “run the experiment” to confirm it as a fact, but it’s not clear from the thought experiment whether Mary has to. So if I were to say, “Mary has acquired all the physical information about everyone’s color vision abilities, including her own,” does it include all the counterfactual/dispositional information or not? If it does, then Mary is in a weird position: she is shown a book of unlabeled color swatches, notices how she responds physically to each of the colors, and thinks to herself things like, “oh, so that’s what mint green looks like to me. Cool. But of course I knew I would think this to myself!” The way I read the thought experiment, you’re imagining it wrong if you think of Mary as a human that could possibly exist.

  25. #25 sean samis
    December 14, 2013

    Another Matt;

    Let me cut to the chase:

    You wrot that, “The way I read the thought experiment, you’re imagining it wrong if you think of Mary as a human that could possibly exist.

    If that’s true then the problem is without value. The point of my interpretation was to preserve some value to the problem. Instead, you wish to replace it; that is your project. We’ll critique it when we see your results.

    sean s.

  26. #26 Another Matt
    December 14, 2013

    I agree that the problem as it stands is without value. And so the conclusion that it is trying to prove is also without value. Here is that conclusion, for emphasis:

    What will happen when Mary is released from her black and white room or is given a color television monitor? Will she learn anything or not? It seems just obvious that she will learn something about the world and our visual experience of it. But then it is inescapable that her previous knowledge was incomplete. But she had all the physical information. Ergo there is more to have than that, and Physicalism [i.e., materialism, the denial of dualism] is false.

    Preserving some value to the problem along your lines is totally interesting, but your version of it no longer supports this conclusion; it gets away from the reason the thought experiment exists in the first place. I think that’s about all I have to say — thanks for the discussion.

  27. #27 sean samis
    December 15, 2013

    Another Matt;

    Perhaps I’m mistaken (God knows that happens a lot!) but I thought the purpose of this problem was to decide whether the conclusion was valid or not. My “version” (which merely clarifies some poorly written parts of the problem) demonstrates (IMHO) that the conclusion is wrong.

    I think my analysis is completely in accord with “the reason the thought experiment exists in the first place”: to determine if the conclusion is correct or not. It’s not correct.

    Anyway, thanks to you also for the discussion, and Happy Holidays.

    sean s.

  28. #28 sean samis
    December 15, 2013
  29. #29 sean samis
    December 15, 2013

    … or not. The html clearly didn’t work. Ah well. Happy Holidays.

    sean s.

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