14 ms·

What did Mary know? A thought experiment about consciousness (2013)

• psychoslave 4y ago
  It seems that people who were born blind dream in visual images[1]. So certainly Mary had experienced colors in her dreams. [1] https://www.wtamu.edu/~cbaird/sq/2020/02/11/do-blind-people-dream-in-visual-images/ https://www.wtamu.edu/~cbaird/sq/2020/02/11/do-blind-people-...
• dale_glass 4y ago
  The easiest way I see to parse this is by doing a thought experiment: what if the human brain was indeed a hardware/software device, how would this work? Eg, can you take a webcam image analysis software and teach it that apples are red without ever showing it something red through the camera? I'd say the answer is obviously dependent on the design. Yes if you have enough control over the software. You can introduce the shape of an apple into its dataset, and tell it that an apple shape is such and that it rates highly on the R channel. Then the program will upon seeing an apple for the first time say "Yup, this is indeed a red apple" and be entirely "unsurprised". No if the system is isolated enough. Eg, if the recognition system is locked in a black box and your only controls are a query of "what is this?" and a command of "remember that the thing you're looking at now is X", then you don't have the access to introduce the information above by any other means than presenting an object to the camera. Both systems are still 100% physical though. The question is what humans are most similar to and I think the second option is most likely. Think of that for instance I can't mentally measure my blood pressure, or heart beat, or make myself vomit. There are some things my body does that are outside of my direct control. Given that, there's no reason to assume then that by just reading or listening to information that I would necessarily have any pathway from there to the depths of my visual system.
  • simonh 4y ago
    Right. The thing is there are multiple different ways to represent a piece of information like 'red' that each have different advantages and disadvantages. Pixel data in an image file, weightings in a neural net, a flag in a database and many many variations on each of these. An image classifying neural net doesn't just store 'red apple' as a colour value like an image file, but as relationships between all sorts of other aspects of images it has been trained on. It probably doesn't even store 'red' distinctly at all, the weightings that represent red in the classification of a red car may well be completely different from the weightings that identify red in images of apples. Likewise with human brains. So when Mary sees a red apple, that will evoke different responses than she would have to a red square or a red car. It's the relationships between attributes that matter at least as much, if not vastly more than the attribute itself in isolation.
  • BoardsOfCanada 4y ago
    My understanding of the thought experiment is that it is not about being able to detect red, but about experiencing the feeling that it is to see red. So in a hardware/software device, could we make the hardware experience seeing red the way you or I experience the color red. My strong intuitive hunch is that we'll never build something electronic that can experience things (that it feels like something to be that device). Compare this to how our immune systems works, it reacts on inputs and does very complex things but without experience. There could be beings or machines that could have this exact discussion like that, learning things, agreeing, disagreeing but without experiencing anything.
    • Isinlor 4y ago
      I'm quite sure that my immune system provides me with experiences. For example, I certainly can feel swollen lymph nodes. My memory of swollen lymph nodes is about as vivid or detailed as that of headache.
    • naasking 4y ago
      > My strong intuitive hunch is that we'll never build something electronic that can experience things (that it feels like something to be that device). The Bekenstein Bound tells that us that any finite volume has finite information. That means our brain is describable by finite information, including our feelings. So why can't that information be translated into an electronic form? The only way out of this conclusion is to assert that "experience" cannot be captured by physics. Is that your position?
      • BoardsOfCanada 4y ago
        Yes. I used to be a hardcore materialist, I studied applied physics at university as a young know-it-all, and never reflected on how absolutely weird "experience"/quale is until years later and changed my mind. But if anyone can explain how to get from matter to experience I would be relieved :) What do you think?
        • naasking 4y ago
  • kordlessagain 4y ago
    Only some apples are red. And, most apples don't even look like apples. Every apple you've ever eaten has its origins from a single tree, found by chance in the past by people who are now wealthy from selling delicious apples plucked from a forest of clones. Most people (I've asked) will visualize a red apple if you ask them to visualize an apple. Additionally, some people don't visualize apples. They may, for example, only visualize people. Finally, some people don't visualize anything. Some of those people still know what an apple looks like, even if it's the size of a grape, purple when ripe, and has never been seen before.
    • Quekid5 4y ago
      > Most people (I've asked) will visualize a red apple if you ask them to visualize an apple. That's fun! To me apples are green by default. How many people have you asked? (Just curious)
      • kordlessagain 4y ago
        I've asked at least a hundred people. Sometimes they are reported as green!
      • pixl97 4y ago
        I think for a lot of people, at least in the US, the idea of an apple being red is presented by cartoons, for example Snow White. That along with the tyranny of the Red Delicious being foist on kids that didn't know any better. If you said imagine a good tasting apple I would envision something colored like a honeycrisp. Or an apple pie apple being green.
• albertzeyer 4y ago
  Well, seeing some new color for the first time will cause some sensory input signals to become active which have never been active before, and that will cause some neurons patterns to emerge which have not been there yet, and this will surely have influence, e.g. synaptic plasticity, i.e. in other words the brain has learned. But then, the brain also learns basically all the time. It's constantly changing. It is not something static. But is that really the question?
  • deleted 4y ago
    [deleted]
  • dsego 4y ago
    what happens between neuron patterns emerging and me experiencing red, well, being red, instead of let's say blue for the same sensory input? where is the mapping, or are we all seeing totally different colors? even so, where does this information about the quality of this color come from.
    • pixl97 4y ago
      The 'color' you experience is meaningless in itself. The feeling behind it is what's important and we see that it is often shared between social groups, but can vary between different social groups. Why? To keep you alive. If we associate red with danger, it doesn't matter if we experience the same color in our minds as long as our group associates the same physical wavelength. The same goes for color experiences with much longer payouts. If you need to collect the yellow berries to survive the winter then having a qualia of enjoyment may increase our ability to survive.
      • dsego 4y ago
        Thanks for answering, but it seems like a utilitarian cop out, hand waving the problem aside. To keep me alive I just need to react to the physical wavelength, the internal experience isn't really necessary, sort of like reflexes. A robot can just as well be trained to react to red wavelengths detected by some sensor, but it doesn't have an internal experience of that color. I don't think it's meaningless.
• thanatos519 4y ago
  What if it was a green, yellow, or pink apple, or an apple painted violet? She would also need someone to tell her the common name of the new visual sensation she experienced. In any case, it is just another phenomenon in the bucket of 'being Mary'.
  • pdonis 4y ago
    > She would also need someone to tell her the common name of the new visual sensation she experienced. No, she doesn't. She has complete knowledge of all the physical facts. That includes complete knowledge of what patterns of sound waves are used by humans to name visual sensations, since those are physical facts.
• claudiosf1 4y ago
  "Jackson’s thought-experiment about Mary challenges physicalism in the following way. Physicalists claim that physical science can fully explain consciousness. However, when Mary sees the red of the apple, says Jackson, she learns something new, despite having previously learnt all the physical facts about colour vision. Thus, argues Jackson, Mary has come to know a non-physical fact; so proving that not all knowledge is physical." I can't see how this result proves anything. Consider the analogous experiment of "Mary learns to cycle by reading books". Surely she can learn all the physics behind cycling without truly knowing how to cycle, and one could similarly conclude that there is something beyond the physical mind behind this skill. Nevertheless, we can use reinforcement learning to teach an ANN to cycle, and that doesn't mean our robot has acquired a metaphysical consciousness. You can still interpret both results from a physicalists perspective as in "some learnings require specific physical stimuli".
  • Isinlor 4y ago
    If she knows everything about colors then she could remove her retina and stimulate her visual nerve with the identical signal as color red would produce. I'm 100% confident that she would experience red without actually seeing red. Consider a separate thought experiment. A Bob lives in a bubble that does not allow liquids to exists outside his body. If he puts his hand in a completely dry glove sticking outside the bubble and surrounded by water he will experience wetness despite having no contact with water. We know that our body does not have direct sensors of wetness. We experience pressure and heat loss as wetness. So you 100% can experience wetness without getting wet.
    • hdjjhhvvhga 4y ago
      > So you 100% can experience wetness without getting wet. Which leads us to the interesting conclusion "you can experience everything without actually experiencing it" which is a bit Buddhist.
    • nkrisc 4y ago
      What is “wet” then? Liquid clinging to your skin through surface tension and other forces? If your hand is submerged in a liquid that will not cling to your skin at all, is your hand “wet” while it is still submerged? You’d feel “wetness” according to your definition but your hand would be “dry” when you remove it. I don’t think wetness is defined by future state, but by present state. If Bob is experiencing wetness, then he is “wet”, at least while he experiences it, even if his hand will be dry when he removes it from the glove.
• andrelaszlo 4y ago
  "Consciousness is what keeps philosophers awake at night." Unless they're dyslexic, right?
• narag 4y ago
  A thought experiment seems to be exactly the opposite of an experiment: no experience there. I understand the concept, but every time I see one of these, the most compelling points are for me the ones that show how the setup makes no sense at all because, for starters, there's no way to make a real experiment that's truly equivalent. Edit-> please, think about this: can the "result" of any thought experiment be surprising, not what you expected?
  • svantana 4y ago
    > can the "result" of any thought experiment be surprising, not what you expected? Isn't all of mathematics just thought experiments? No shortage of surprising results there.
    • narag 4y ago
      That's not what thought experiment means.
      • svantana 4y ago
        Here's a thought experiment for you: consider the hypothesis that you're wrong.
  • n4r9 4y ago
    > can the "result" of any thought experiment be surprising, not what you expected? Isn't Schrödinger's cat the classic example of this? Physicists at the time typically thought of quantum effects (like superposition) as being confined to the microscopic realm. Schrödinger pointed out that if you take the principles of quantum theory as serious and objectively ontological, then you end up with macroscopic superpositions.
    • narag 4y ago
      The problem is that you can't know if the cat is dead or alive unless you open the box. Schrödinger conceived the experiment to "show" that the premises lead to an absurd result: that the cat is dead and alive at the same time. But now people either consider it plausible (in multiple universes or depending on observer) or try to explain how superposition is lost before it reaches macroscopic objects.
• edrxty 4y ago
  Is this another ill-conceived argument for the existence of classical Christian metaphysics? They'd have a much easier time concealing the bias if they didn't construct it exclusively from the themes of genesis... Woman... Knowledge... Apples... Who forgot to bring the snake?
  • andybak 4y ago
    I suspect this is entirely in jest, but one can never be sure.
• distcs 4y ago
  > If we were to show Mary a blue banana instead, she would not be fooled; she would know that it had the wrong colour, argues Daniel Dennett, in what he coined the ‘blue banana trick’. Why won't she be fooled? Is it because she already knows that a banana has a different color than the sky and she knows the sky is light blue?
  • pdonis 4y ago
    > Why won't she be fooled? Because she has complete knowledge of all physical facts. Dennett is a physicalist, and to a physicalist, perception and experience are physical processes. So Mary has complete knowledge of them. That includes complete knowledge of what she will experience in response to any physical stimulus. > Is it because she already knows that a banana has a different color than the sky and she knows the sky is light blue? That's one tiny piece of the physical facts that she knows, yes.
• PixyMisa 4y ago
  The thought experiment simply contradicts itself. The premise is that Mary knows everything there is to know about colour vision. If this is true, then she knows what it is like to see colour. If she doesn't know that, then the premise is false. It's just nonsense.
  • riversflow 4y ago
    That's literally the point of the thought experiment. Thought experiments are mostly nonsense, the point is to help differentiate different phenomenon through extreme, contrived examples. The point here is that despite knowing the entirety of the corpus of knowledge about colour vision, she still doesn't know everything that there is to know about it if she hasn't actually experienced seeing the colour red.
    • magicalhippo 4y ago
      > The point here is that despite knowing the entirety of the corpus of knowledge about colour vision, she still doesn't know everything that there is to know about it if she hasn't actually experienced seeing the colour red. But that isn't the point being made in the article. The point being made is that this is somehow non-physical, which is obviously wrong: Thus, argues Jackson, Mary has come to know a non-physical fact; so proving that not all knowledge is physical.
  • distcs 4y ago
    This contradiction is literally being discussed in the article!
    • magicalhippo 4y ago
      Jackson's thought experiment is exactly like the proof that x = y leads to 1 = 0[1], in that the conclusion doesn't follow from the premise. So how is it a useful basis for any arguments? If the argument is flawed, how can there be any contradiction? [1]: https://math.hmc.edu/funfacts/one-equals-zero/ https://math.hmc.edu/funfacts/one-equals-zero/
  • 4y ago
• the_af 4y ago
  I understand the experiment could be reframed to fix this "bug", but it's flawed: when Mary sees a red apple for the first time, some optical/neural pathways get excited that weren't before. She knew everything there was to know about the color red, but a specific physical experience was missing (physical, with observable physical changes that can be physically measured). So this isn't about metaphysics or anything. Had Mary stimulated her optic nerve with an electric current to simulate a red apple, we'd be closer to the intended message of this thought experiment (and I'd argue in that case that a physical apple and a simulated one are indistinguishable).
  • distcs 4y ago
    What is your point? The article puts forward this point too among many other counterpoints.
    • the_af 4y ago
      I think I explained my point, why do you ask? But to summarize for you: it's not true that Mary "knew all" just by reading about the color red. The premise is false. She lacked one bit of information: to have her optic nerve stimulated by a red apple. Note this isn't metaphysical, it's physical; such stimulation can be physically measured and she lacked this experience, which -- to emphasize the point -- is entirely physical. Again, I think the thought experiment can be probably reframed in order to fix this flaw, but Mary and her red apple as currently stated are not convincing of any duality.
      • distcs 4y ago
        I am trying to understand what point you are trying to express that is not already very well expressed in the article. Or are you repeating one of the several counterpoints mentioned in the article? If so why is this one counterpoint more important than the other counterpoints made in the article?
        • PixyMisa 4y ago
• ChaitanyaSai 4y ago
  Another way to rephrase this is: Does the person who has read absolutely everything about love, know what it feels like to love? This thought experiment relies mostly on how fuzzy our understanding of consciousness is, and how vague our definitions of it are. It confuses conscious 'knowing' and conscious 'seeing' (or 'feeling' in the love example), which are two different things. How can I state this confidently? Because we do have a wonderfully detailed computational model for consciousness, which explains a ton of data! It's a real shame that it's largely ignored or unknown even in the field of neuroscience. I've written about this here: https://saigaddam.medium.com/understanding-consciousness-is-more-important-than-ever-7af945da2f0e https://saigaddam.medium.com/understanding-consciousness-is-... As I mentioned there, I also co-authored a book (https://www.goodreads.com/book/show/58085266-journey-of-the-mind https://www.goodreads.com/book/show/58085266-journey-of-the-...) where we go into this theory in greater detail. Stephen Grossberg and his work really do deserve greater attention. Most discussions of consciousness are frustratingly incomplete because they leave out a crucial aspect. Who is the “experiencer”, that is consciously “experiencing”? How is that "I" put together? Only a clear answer/theory that attempts to define and construct both the experience and experiencer will allow us to see through these cutesy philosophical constructs like Mary the color vision expert, philosophical zombies and more. Here's a definition, based on the computational model I mentioned above, that makes a lot of sense. Consciousness is the constellation of past experiences experiencing the present, assimilating it to act and prepare for future opportunities.* So you are nothing but a bundle of experiences. Each new experience, after it is had, is added to this bundle, and changes you. With that in mind, here's how Mary's experiences make sense. Mary could read everything there is about color vision, but all of these are just semantic experiences. They become a part of her. When the first visual experience happens -- when she actually sees red -- she has absolutely no visual experience to fall back on that explains this. Reading about it, does not in any way reconstruct the unique neural patterns going all the way from her retina to her inferotemporal cortex. The experience is utterly new, and as with all new experiences, it is memorable and retained and becomes part of her. That sadly, also means that all subsequent experiences of red are not as vivid, because they are now matched against what came before. (This invokes the idea of predictive inference; there are reasons to do this -- it is metabolically cheap to just classify and forget, rather than retain the full pattern.) *-this definition of consciousness leaves out how an experience is constructed. To answer that very briefly, it is when the sensory data streaming in is matched locally and globally against past experiences and a broad agreement (a “resonance”) is achieved. This is obviously a very lossy summary. You can read this for article for a complete picture: https://www.sciencedirect.com/science/article/pii/S0893608016301800 https://www.sciencedirect.com/science/article/pii/S089360801...
• lelanthran 4y ago
  It's sad to see so many people focusing on the color aspect of the experiment, completely ignoring the argument in the process. Look at it this way - switch out "red" for "parental love" and then re-evaluate the argument. Mary has read and currently knows everything there is to know about the bond a parent forms with their child[1]. And then Mary raises a child ... [1] An adopted child would do - then there's no claim of biological hormones affecting the knowledge.
• simonh 4y ago
  How is dualism supposed to resolve this question, any ideas? I don't really see what it brings to the table on this. The article doesn't seem to address that. What frustrates me with dualism generally is that it doesn't actually explain anything, it just seems to say "we don't understand how this works physically, therefore woo". It's the god of the gaps argument all over again. I may be seriously mischaracterising it, and that's not my intention. I've just never come across any positive arguments for dualism having any explanatory power on it's own terms, and I'll be very happy if I'm wrong on that. What characteristics or attributes might this non-physical quantity or influence or 'stuff' have that answers any of these questions?
• ankurdhama 4y ago
  The experiment ask "Has Mary learnt anything new about the colour red upon seeing the colour for the first time?" Yes, she has learned to detect red colour using her eyes.
• hyperman1 4y ago
  To me it seems a word game, as happens so many time with philosophers. What is meant by the words 'knowledge' and 'consciousness', exactly? Define them strict enough, and the paradox will evaporate. E.g. in this case, let's define 'scientific knowledge' the ability to predict the future, and to choose scenarios where a specific future happens. Science is then the process for generating scientific knowledge. Newton's theory, for example, allows us to predict the future of an object with mass, and choose ways to put such objects together in such a way that they end up in a specific place at a specific time in the future. In this case, Mary knows everything about 'Red'. This means she can predict what happens when something red interacts with something else. If she also knows everything about 'Mary', she can predict her own surprise at seeing something red. She can choose actions that make her come in contact with something red in the future. She can then still feel surprised at experiencing red.
• pedrovhb 4y ago
  I have a take that I'm torn on about whether it misses the point/is covered by one of the arguments presented in the article, or makes sense - It seems to me that one can know about all the physical properties of color before having experienced it, and still not have any expectations of knowing what their perception of seeing a given color would be like. Those are two different knowledge domains which are relevant to us, but which have no real importance in a "universal truth" sense. Imagine we were talking about red with an individual of an alien species which doesn't have eyes or other light sensing organs, but is technologically advanced enough to know about photons and the physical properties of light and use them in their navigation systems (maybe not unlike we understand something about radiation without being able to feel it). We'd agree on the existence of the "red" wavelength, and we'd agree that certain surfaces reflect it and certain bodies emit it. But it'd be rather futile to try to explain seeing the color red to the alien even if we could, because it's irrelevant to them; it's just some being's perception of a physical quantity, a delta in the chemical balance of our brain soup. To them it's no more special than the feeling of hunger, a crude reflex which evolved so our bodies could tell us we need sustenance. Importantly, there's nothing of practical value about color itself that they could learn from the discussion. In that sense, does Mary really learn something new about color, or does she just learn about her own perception of it? Are those two things really related?
  • beowulfey 4y ago
    I think you are absolutely right, but the reasoning behind these thought experiments are such that we can understand consciousness, and what it means “to perceive” something. So in your example, we may recognize these aliens as conscious beings, but how do we know that? They do not experience the world in the same way we do, and yet they clearly must have something in common with us to produce a conscious being. The argument proposed by physicalists says that there must be some new state inherent to the apple that registers in our brain as “red apple”. But what is the likelihood that all humans even produce the exact same state in the brain for the same item? Or in your aliens, that can’t even see the color? The non-physicalist argument is that the experience of seeing that apple is unique to each one of us, and emerges uniquely for every brain. That state of the brain that we “learn” upon seeing a red apple for the first time is unknowable to others, yet is a core part of the conscious experience… thus, non-physicalists believe we may never truly understand how consciousness works. In other words, even if we may recognize these aliens as conscious, we may never be able to explain how we know… since we can’t define how it arises. (This is my interpretation of the argument—not guaranteed to be correct)
• Gunax 4y ago
  Mary learns nothing and the physicalists are correct. Since Mary knows everything about human physiology and physics, she is able to simulate a neural vision system within her own brain.
• swader999 4y ago
  I wonder if this experiment could be ran in real life today with EnChroma Color Blind Glasses and a cohort of color blind subjects.
  • joshcryer 4y ago
    It would be akin to a color blind person being able to pass the Ishihara test (color vision tests with the splotches and numbers), which the EnChroma glasses don't do.
• px43 4y ago
  My current understanding of recognition (I think it was pulled from a Kurzweil book I read recently, so grain of salt etc) is that humans have on average 150k recognizer circuits[1], which are long columns that permeate a few layers of our brain. Signals come in from various sensory inputs, and it lights up some subset of recognizer circuits, and that data is then passed on to other parts of the brain to analyze the context. Every letter of the alphabet, and every word you use regularly, and every object you see, has a handful of associated recognizer circuits which will trigger given the shape, smell, or the sound, etc. When one of these circuits goes unused for a while, it can be repurposed. Personally, it kind of blows me away that we can function as well as we do while only being able to immediately recognize 150 thousand total concepts. It's such an easily comprehensible number, yet completely defines our perception of reality. If Mary had never seen the color red, so no matter how hard she studies, her brain will not have the circuit capable of recognizing the color red, simply because that particular signal has never entered her brain. She might be able to acquire it later though. Colorblind people get the protein injection that allows them to see the third color, my understanding is that it takes a few months[2] for it to take effect, which lines up well with my understanding that it would need to rewire a bunch of recognizer circuits through repeated exposures. [1] https://numenta.com/neuroscience-research/cortical-columns/ https://numenta.com/neuroscience-research/cortical-columns/ [2] https://www.npr.org/2009/09/17/112897277/thanks-to-gene-therapy-monkeys-see-in-full-color https://www.npr.org/2009/09/17/112897277/thanks-to-gene-ther...
• hbrn 4y ago
  A lot of these thought experiments are just semantic arguments in disguise. We think we disagree about physicality of consciousness, but we're actually disagreeing about meaning of the word "all". She knows all there is to know about colors. This might be a good linguistic discussion, but it's unlikely to move us anywhere on physicality of consciousness.
• nathias 4y ago
  This paradox only shows that the definition of knowledge used to produce it was wrong.
• callesgg 4y ago
  Mary would probably not be able to see that the apple was red. Just like I can’t hear the difference between sounds in many Indian words Mary would not be able to differentiate colorized things from non colorized things. Her brain would have learnt to ignore the color signal that the eye provides. Just like my brain has learnt that the different sounds in Indian words is not worth processing.
• nonce42 4y ago
  What I find interesting is that this seems to be an obscure philosophical thought experiment, but it's actually highly political and turns up all the time on, say, Twitter. Specifically, how do you compare "factual knowledge" and "lived experience", and which is more important, and who is the "expert" on things. To make this concrete, consider expertise on England. Suppose Prof. Smith has never been to England, but has studied it in detail for decades. And suppose Mr. Chav has grown up in England, but is uneducated and isn't even sure who is the Prime Minister. Who is "allowed" to talk about England? Smith, who knows all the facts, or Chav who lives there and knows what it's like? Can Smith tell Chav that he's wrong about England, or does Chav's lived experience matter? (I'm using England as a less controversial example, but this usually happens in discussions of race or gender.)
  • hebrox 4y ago
    Isn’t that question easily answered if we know if it’s a “factual” or “lived” subject that is being discussed?
    • redbar0n 4y ago
      are lived subjects not also factual subjects?
      • fluoridation 4y ago
        Only in the same sense that anecdotes are data.
        • redbar0n 4y ago
          You mean as one data point?
  • jrm4 4y ago
    I think what you're suggesting here might be both more and less complicated than you're making it, owing precisely to the presumption of the "identity" of the thing called "England" (very similar to race and gender of course). As a black person, I just find that there's probably something along the lines of the philopsohical idea of "things are what they do," which also means occasionally getting comfy with contradictions and paradoxes. E.g. concretely, I can (well, must, really) accept the idea of "blackness" being a very flimsy concept from a scientific view but a very strong one from a social/political one.
• torcete 4y ago
  I have been very interested in Buddhist non-dualism recently. Although the philosophical implications are very profound assuming that is true, but I don't. For me consciousness clearly emerges from our physical body and not the other way around. However, I admit that is fascinating and learning about how self-identification can lead to suffering is eye (mind?) opening.
• kelseyfrog 4y ago
  It's pretty clear Mary learns something new upon viewing the red apple and it's easy to create an experiment for this. We'll continue using Mary's monochrome example as a basis. Consider the following experimental setup: Mary is prepared with all the knowledge about colors and apples and every other odd thing just as before. Mary is then instructed to view an apple and then subsequently asked to follow the instruction printed in red in the next room. In the next room there are two sets of instructions. The instructions in red say "Exit through the left door" and the instructions in blue read "Exit through the right door". Behind the left door is a million bucks and behind the right door is nothing. Does Mary get the million bucks? Would Mary get the million bucks had she skipped looking at the apple? It's probably helpful to do this with several Marys and ask, is there evidence that our Marys choose the left door greater than the expected probability attributed to random chance? If we can answer yes, no, and yes, then we can infer that choosing the view the apple changed Mary's mental state and that yes, she did learn something new that helped her to identify the correct text.
  • obastani 4y ago
    I'm not sure about that. If Mary knows all the physics of light, she can design and set up a sensor to detect the color of the apple and the instructions, just like we have sensors that detect ultraviolet and infrared light. Just as we will never know how it feels to "see" ultraviolet light, this thought experiment is about Mary's subjective experience perceiving color, not her ability to determine the color of the world around her.
    • kelseyfrog 4y ago
      Mary is using sensors either way: they either come pre-installed or after market. On a more serious note, I'm taking the question in the article at face value, "Has Mary learnt anything new about the colour red upon seeing the colour for the first time?" If the author really meant it to be a question about the subjective experience of seeing, they should have simply written a better question.
      • jiocrag 4y ago
• otikik 4y ago
  The experiment is flawed in that “Mary knows something new” is very loosely defined. We know new things constantly, to begin with. Our neurons change continuously. As an example- She’ll immediately have a new memory: “I saw the color red for the first time”. Does that count? What about the emotions she might have felt? Elated. Disappointed. Does that count? You are “knowing new things” just by reading these words. There’s also the fact we don’t need a thought experiment for this one. There are rare cases where people have been able to gain sight or hearing via operations or devices. Ask them directly! All of them will say that they had many new thoughts when this happened. That doesn’t imply that qualia exists at all though: > she has gained a non-physical fact She now knows how it feels to see the color red. I don’t think that disqualifies this as a “physical fact”. It could be that the subjective experience can be explained in physical terms, but we humans just not have figured it out. In that case Mary would not have that on her notes, would her? After all, this is a complex problem, I don’t expect conscience to be easily explainable in 2 or 3 lines, the same way that “how does the Linux kernel work?” can’t.
• carapace 4y ago
  This "thought experiment" is pointless. We might as well debate the mechanics of Harry Potter's magic spells. > she grew up entirely in a black and white room, she has never actually seen any colours. White is all colors, or in other words, there is no colour "white", the subjective experience of it is an illusion caused by perceiving multiple frequencies of light simultaneously. This human guinea pig raised in a black and white room will have been seeing red, and green and blue, all her life. In fact the "whiter" the room the more frequencies of light she must be experiencing. When she finally sees an apple there is no new information at all, in fact, she is seeing a kind of shadow. It's the absence of other colours that makes the red noticeable.
• jkingsbery 4y ago
  TL;DR: Plato's Cave meets The Giver.
• rawgabbit 4y ago
  >The ignorant are cocksure, while the wise are full of doubt. If we assume our abilities are limited and finite, we can never be 100% sure of anything. However, we can be 90% confident of things based on: (a) Shared wisdom and learning (b) Scientific research and experiments. Philosophy of knowledge is a tool to get knowledge; it is not knowledge itself. Going back full circle, we believe our abilities are finite and limited. We believe we cannot know everything. We can only be confident based on our limited shared knowledge and scientific discoveries. We expect future knowledge to contradict old knowledge. Philosophy underpins or guides this quest for knowledge. Philosophy are fundamental assumptions or beliefs. e.g. Truth cannot contradict itself. If truth contradicts itself, it is our limited abilities that deceives us.
• yongjik 4y ago
  I'm not sure if this experiment means anything. Consider a much more mundane(?) example: echolocation. Bats can "see" the world around them via ultrasound. Humans can research everything about how it works, including acoustics, physics, neurology, bat anatomy, you name it, but we will never experience it the way a bat does. So... does that prove that human consciousness is non-physical? ...I'm sorry, what? That sounds like a complete non sequitur to me. Which is exactly how I feel about the original argument.
• anon291 4y ago
  This does not seem a complicated question. No amount of words or verbal explanation can convey the full sense of qualia. You cannot describe the phenomenon of sight fully to a blind person. This seems more a limitation of language than consciousness. I mean... surely a pig sees just fine, but you cannot explain the physics of color to them.
• mcguire 4y ago
  "Many black and white books and TV programmes have taught her all there is to know about colour vision. Mary knows facts like the structure of our eyes and the exact wavelengths of light that stimulate our retinas when we look at a light blue sky." This is a serious hole in the argument. "All there is to know about color vision" is an abstraction---it's "about" color vision; it's not vision. The experience of color vision is a different set of data than wavelengths and eye structure.
• adamc 4y ago
  Loved this. Thank you for sharing.
• superb-owl 4y ago
  I've had a handful of arguments w/ smart people about Mary's room lately. The conclusion I've come to is that the disagreement typically rests on how you define "knowledge." To many, "what the color blue looks like" does not constitute knowledge, because it doesn't enable you to make any additional quantitative statements beyond what you would know from an objective study of color/light. But in common usage, we say things like "I know what that feels like," meaning "I've felt that before." In the end, this is just a semantic disagreement. But there are still philosophers like Dennett who take an even harder position, saying that functional knowledge is identical to experiential knowledge. I still can't quite wrap my head around this idea.
  • layer8 4y ago
    To me, the knowledge about the qualia of some color is just knowledge about (some distilled form of) how you process the perception of that color internally, which may be slightly different for different people, and which is not directly observable (with today’s technology). There’s nothing particularly surprising about it, nor does it contradict a naturalist/physicalist view. Those who claim that functional knowledge is identical to experiential knowledge probably classify the internal processing of the brain as functional, and therefore classify knowledge derived from it as, fundamentally, functional knowledge.
  • missingrib 4y ago
    >But there are still philosophers like Dennett who take an even harder position, saying that functional knowledge is identical to experiential knowledge. If you deny the existence of consciousness or qualia then you are making that claim. Strict physicalists all are committed to that claim.
• prng2021 4y ago
  I’m fully in the physicalist camp. I think this is a flawed thought experiment because humans are incapable of knowing everything about seeing red until they actually experience it. Here’s what it’d like be if we actually could without experience: Suppose you take a perfect snapshot and learn the exact position of all atoms in a persons brain after they see a red apple. Now imagine that humans have the ability to move all the atoms in our brain to be in those exact same positions, at will. So without the red photo receptors in your eye actually detecting anything red, you can make yourself see red apples at anytime. Mary could do this even before ever actually seeing red or even when seeing something that’s reflecting a completely different color to her eyes. Since we don’t have this magical ability, having an understanding of all the underlying physics and biochemistry of color perception does not really provide everything there is to know about seeing red.
• clavalle 4y ago
  Can words and word structure capture all ideas? (I'm using 'words' in a very broad sense as packets of information that can be communicated sequentially). It's a broader and easier to answer question that covers this specific case. Another interesting question is, are there disjoint sets of words and word structure (meaning that they cannot be 'transpiled' 1:1 into one another) that can describe and predict physical phenomena just as accurately as another? Particularly the set of words and word structure that we've come up with so far as a species? Some recent experiments seem to suggest, yes, there are combinations of variables that can fully characterize certain physical phenomena that cannot be translated into our current understanding. This means there can be parallel and equally valid and precise models of reality. https://www.nature.com/articles/s43588-022-00281-6.epdf?sharing_token=hFKezKzzC3n7kXcZ3ZaTKdRgN0jAjWel9jnR3ZoTv0OId_6dQRGZRNcTFlGzITvHaatdlk0-Z0-SOAFts7DUKd8fDL6wtMOX2d83wHyprfJDyqEWN0162YQ-k0dm6hubXMdsvIe-oS3ILmr1XiQDqbE6wihE3nY8HUYZShLelN4%3D https://www.nature.com/articles/s43588-022-00281-6.epdf?shar...
• akomtu 4y ago
  "consciousness is all about the brain; or more specifically, it is identical to the brain" That's easy to disprove with the computer analogy. If transistors are simplified neurons and CPU chips are brains, then software is consciousness. Just like software is an immaterial something that uses magnetic medium to run on CPU, human consciousness is immaterial something that uses magnetic medium to run on neurons. Mind is parricularly fast type of hardware, an equivalent of GPU, that runs imaginary experiments. One thing that's certain is that software doesn't emerge from transistors and barely can it be understood by inspecting those transistors. When Mary sees a red apple for the first time, her mind records the relationship between "red" and "apple", while her consciousness registers the new waveform produces by red receptors in her eyes. The richness of this waveform is limited by her eyes, whether they capture basic redness or the entire spectrum, and by her conscioussness that may or may not be able to register waveform of such complexity. She gets to experience a surprise because she hasn't seen such waveform before, and her mind will put the red color into its proper place by recording relationships between observed objects. Mary can know what it's like to be a bat because bat's consciousness is much simpler: any waveform that can exist in the bat's consciousness can also exist in Mary's consciousness. The reverse isn't true.
• nojvek 4y ago
  What is a color image? An RGB image of pixels. Put another way, three images with red, blue and green filters. If Mary could only see black and white, reading every book about color would not give her the experience of red. Like a child could read every book on cycling, but not know how to ride a bicycle. However if Mary could interface a color camera to her visual cortex, she would experience red over time. She could add a bigger spectrum of infra red and ultraviolet and be able to experience more than a normal human being. Similarly for cycling, if someone had VR goggles, and could simulate forces on their body, they would learn how to ride a bicycle. Words and writing are a highly compressed version of shared experiences. When we read "red apple fell from the tree", our minds are creating simulations of apple, tree, falling symbols from the raw experiences we've perceived. To understand an "apple" we have to see many different kinds of apples, taste them, touch them, feel their texture and weight, smell them, the sound when we bite them. All of that is compounded into the symbol "Apple". But we also disambiguate the internal symbol {apple} from the fruit Apple and company Apple.
• Arrekin 4y ago
  Seeing color(qualia) does not provide any additional information. They are just a tool your brain uses to speed up processing. Treat is as quick tagging system. It's done inside your head, we don't even know if all people tag colors in the same was(is your red, my red?). Qualia are derived information. Your senses get information, and you get some processed result. There is nothing added(beyond what your mind may add, but that's not part of the original information). You could swap red for green, green for blue and nothing changes. Imagine a wall of text, a very big one. To read it you have to carefully go line by line, focused on the content. It takes a lot of time to do. But now imagine you evolved to read such text walls. Now it's not hard, because nature developed special structures to process them, and now you have dedicated, and optimized region in the brain to handle them. You just glance at that massive text and "see" all the content, it sings to you, you understand it instantly, maybe even feel parts of it. And seeing is the same. The mass of color information hitting our eye, that for someone without innate ability to process it would look like a bunch of hard to plow through data, for us is just instant. We process multiple frames per second, detect objects, project movements. All of it without even thinking about it. Incredible. All thanks to specialised machinery in our brains. The specialized part does the heavy lifting so we can see our qualia. But it's just a tool, it does not provide additional objective information, as it's only your subjective view of the information that other parts of the brain push to you. It's processed information, enriched, but because of that, it's subjective now.
  • kirkules 4y ago
    Is derived information not distinct from the input? I mean, tagged information tells you about the tagging system in addition to the tagged information. Specifically, it tells you how the tagging system interacts with the tagged information. In this case, from a physicalist perspective, seeing red tells Mary how her specific brain (or whatever physical system explains color sight experiences) interacts with the experienceable subject "red", be it red light or whatever choice you make for the "true" subject for the sake of the thought experiment. The ordinary discussion of the thought experiment simply assumes she can somehow already know this without experiencing it, and hand-waves away concerns about whether she could obtain that knowledge without having the experience (she is a brilliant neuroscientist, after all). My position is that this is precisely the new information she obtains from seeing the apple. The minimum value from a finite list of integers is derived from the list, but until you compute it (the analog of "seeing the apple"), you don't know the minimum. Even if you "know all the integers in the list" otherwise. Edit: typo
• kirkules 4y ago
  This thought experiment is a wonderful demonstration of the limitations of thought experiments in philosophy. The premise of a thought experiment used in this way is that the truth of the matter is ultimately to be found in your intuition. One just needs to properly ingest the experimental setup, and the right conclusion will lay itself bare. This experiment is as absurd as the Chinese room experiment. You will be told that you have only properly understood the experiment's setup if you accept that Mary can somehow have learned all physical facts about a chosen color without experiencing seeing the color. It begs the question, because it explicitly claims that knowledge obtainable only through experience is "not physical" (Mary somehow "knows" all physical information about the color before experiencing it). "But wait, if experiencing red added new information, then experiencing red must not be physical, because... we assumed experiencing red is not physical." edit: left out a space
  • mensetmanusman 4y ago
    The Chinese room experiment is less absurd than the existence of consciousness though.
    • kirkules 4y ago
      No it isn't.
• scott-smith_us 4y ago
  You can learn all the biochemistry about a strawberry, but actually _tasting_ one is going to be a new experience. I don't see any need to bring in metaphysics to explain this (in fact, doing so indicates a confusion of ideas to me). When we describe sensory experiences to one another, we usually do so in comparisons. "It tastes like chicken." "They look like little blue bananas." "It smells like almonds and paint thinner." Of course there will be a gap in understanding if Mary has never tasted chicken, seen the color blue, or smelled paint thinner. > ...despite having previously learnt all the physical facts about colour vision... Well, we _could_ simply include scratch-and-sniff in our physics books... If Mary never actually had examples of the different colors, then she wouldn't know how to recognize a color when she eventually saw one. But that's because she (and pretty much everyone else) can't synthesize accurate sensory simulations given information like frequencies or wavelengths. One could imagine a machine that could take the physical description of a color, taste, smell, and stimulate Mary's brain to simulate a sensory experience. No metaphysics necessary.