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.
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.
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.
> 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?
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 :)
Thanks for the link. It seems to me though, that it's no easier to explain having the illusion of experience than to explain actual experience (and vice versa).
I've heard Joshua Bach talk in similar terms and I frankly do not get it.
> It seems to me though, that it's no easier to explain having the illusion of experience than to explain actual experience (and vice versa).
The paper goes over that too: 1. The brain uses information to build models, 2. all brain models are necessarily inaccurate.
Therefore quale are inaccurate models of perceptions and/or models of perceptual memory, where some information has been thrown away, as we do with all models. The redness of an apple is a distorted sense memory of the apple, just with all the "appleness" thrown away leaving only the "redness", which is why they seem so vague and ephemeral.
I'm pretty sure I'm missing the main point of the paper and I'll read it again tomorrow.
If I and some other people would follow a certain algorithm, the one in the paper, but refined and perfected for a thousand years... Calculating with pen and paper the progression of states from a suitable initial state... Would an illusion of experience/qualia appear somewhere just from our calculations? Would it feel like something to be the state represented in the numbers?
> Calculating with pen and paper the progression of states from a suitable initial state... Would an illusion of experience/qualia appear somewhere just from our calculations? Would it feel like something to be the state represented in the numbers?
No, why would some data scribbled on paper describing qualia in a model of a brain reproduce that qualia in your brain?
If you write code on a piece of paper, does your laptop suddenly execute that code? If your laptop takes a picture of that scribbled code, does it then execute that code? If you take a picture of it and then OCR it, does it execute that code? If you take a picture of it, OCR it, and then feed it to the right compiler/runtime does it execute the code?
As you can see, there are numerous layers of translation to get the information in the right form and in the right place. "The right form" for our qualia is the form we evolved to perceive. I'm not sure why one would expect information in any other form to produce quale.
Not in my brain, in some context within the numbers. It seems that it's purely about measurement, modeling, errors, and other things that can be expressed as a computer program. I only chose pen and paper for the whole process to seem less magical. Suitable inputs from the programs "environment" would be incorporated in the updates of the state.
> Not in my brain, in some context within the numbers.
Then yes. As I said, quale are sort of information stripped models of our perceptions, but divorced from direct perception, and this lack of a direct link is why they seem ephemeral and mysterious. If you believe perceptions have a formal model then quale are a projection of those.
> And this is the hard problem of consciousness, how it is even possible to evolve that.
How was it possible for the eye to evolve? The paper I linked goes over this too: systems that have attention schema models are more efficient and more effective than those that don't.
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.
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.
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.
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.
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.
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.
So again, we're asking the wrong question. If you want your robot to 'experience' the color red, you must first train your robot to not want to die more than anything else while also putting limitations/imperatives on it that it must keep doing things to survive in the meantime.
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'.
> 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.
"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".
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.
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.
> What is “wet” then? Liquid clinging to your skin through surface tension and other forces?
Yes.
> 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?
No. If you submerge your hand in mercury you will not get wet. The same if you coat you hand in aerogel. It is empirical fact that people do not describe this situations as being wet.
I distinctly remember a situation where I was being confused whether my hand was wet or not when wearing gloves. My hand was in fact not wet back then. I went to test it again to refresh my memory and the experience in glove is not identical, but it is certainly sufficiently close to have a potential to confuse. Especially when submerging a hand with glove and without glove the experience is very similar, the biggest difference is when you get the hand out of the water.
It’s similar, but it’s not the same. I’m not yet ready to accept that the sensation of “wet” is only the result of pressure and heat transfer. Which is why, though similar, you can still tell the difference.
> If you submerge your hand in mercury you will not get wet.
Tangent: To what extent is that evolutionary? Wetness being a unique feeling could be, that we have evolved a greater sensory capacity to experience water, due to its abundance and importance.
Thus other words for touch (in English) generalise across a variety of sensory experiences (sticky, slimy, hard, etc.) where as wetness is specific to fluids that behave like water.
If I had a point, I guess it would be that maybe wetness is a especially unique experience. I don’t know whether this makes it a better or worse example to use.
I would argue, in the first case, stimulating your visual nerve with the identical signal as the color red would produce would be seeing red. Your argument is akin to saying that someone born profoundly deaf with a cochlear implant has never heard anything! Additionally, the phenomenon of "red" would seem to be more complex than just a single channel, any human will agree that (256,0,0) is not to the only RGB value that maps to red, but would Mary be able to identify which clouds in a sunset were orange, which red, which pink or purple?
For your second thought experiment, I would argue that wearing a wet glove is not a complete representation of wetness, because of the specific interactions that wetness has on the skin; apart from the sensations of pressure and heat loss, there is also the way that water moves/interacts with the skin making it more grippy, the texture of water and it's surface tension forming drips, and the movement of those drips, and the way wet skin feels different are all part of the overall qualia of wetness, hence why we differentiate between e.g. drenched and misted. There are 6 different mechanoreceptor systems in the skin, and the complete phenomenal concept of wetness likely involves all of them. I also think this is a poor thought experiment, because it necessarily involves water, image Bob exists in a plane of reality without liquid water entirely, would it be feasible for him to experience wetness?
> I would argue, in the first case, stimulating your visual nerve with the identical signal as the color red would produce would be seeing red. Your argument is akin to saying that someone born profoundly deaf with a cochlear implant has never heard anything!
I don't really object to that. My conclusion is that you can know what red is on the level of qualia without getting in contact with approximately red wavelength light. You can know what sound is without getting in contact with pressure waves. You can know what wetness is without getting in direct contact with water.
> I also think this is a poor thought experiment, because it necessarily involves water, image Bob exists in a plane of reality without liquid water entirely, would it be feasible for him to experience wetness?
I don't know. In that plane of reality we would not have evolved a mechanism for sensing wetness.
I don't know if it's possible to experience being in a spacial 2 dimensional reality or spacial 4 dimensional reality. My guess would be yes, but it would require significant alternations to our bodies, mostly brain structures.
Our experience of reality is almost certainly very limited vs. what's possible. There exist distinct human personalities who can see trough each other eyes and communicate with their minds - I'm talking about craniopagus twins.
I'm looking forward to high-bandwidth computer-brain interfaces. Some people may actually get to experience how it is to be a computer or whether it feel like anything at all.
It honestly sounds like a lot of conflating "learning/recognizing X" for "experiences X" (even going so far as to invent a new word, qualia, for that)... which just seems like a bizarre distinction to me.
Exactly, or maybe she simply saw a red apple in her dream. You can think if people as robots and the eyes are sensors that tickle the brain with the red signal. It can happen without actually seeing red. We know this because we have dreams and they are all sorts of sensory experiences that are completely made up by our computer brains.
I don't think people who have never seen red can dream of red. Color vision is acquired as far as I know. Newborns don't have it in the sense that they have to train to distinguish colors.
As such, I find it entirely plausible that Mary would be too old to learn color vision. Much like people born blind cannot acquire full vision later. She might just be unable to experience red. That would include her dreams.
Yes stimulatimg her optical nerves could prepare her to see red. Meaning she'd jave the brain hooked up the right way to see it.
> 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.
This is indeed one of the standard responses to Mary's Room, where experiences like "redness" are not actually knowledge but are an "ability". So Mary doesn't actually "learn" anything new technically, but she acquires a new ability to experience redness when exposed to it for the first time.
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?
> 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.
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.
Right, I agree with everything you say. To me that means the thought experiment was extremely valuable, because it generated a great refinement of our ontological ideas.
It's funny because the author's idea was to discredit the notion altogether, so it's relevant because it failed to do that.
The core of Mary's adventures is a false dicotomy: that matter is the only component of physical reality. But processes, structure and energy flow are as real as matter. Actually, at a very small scale, matter seems to be exactly that.
So as usual with all these dualism "enigmas", the only problem is starting from an old perspective that doesn't play well with current knowledge.
Consciousness seems to be a complex physical process seen from inside itself. There's no mistery or toughness in that, except that we can't compare it with anything else.
We can't use the inside and ouside outlooks at the same time. But Wittgenstein already stated that more than a century ago.
But... none of this makes thought experiments any less helpful or valid. If anything, the fact that Schrodinger's cat achieved the opposite goal implies that it touched on hidden fundamentals in quantum theory.
Why is the cat never assumed to be able to be an observer? Or the flask with poison?
I always assumed everybody understood "observer" to be shorthand for "some entity that irrevocably changes state because of the quantum events", but I'm starting to realize that lots of people, even the famous physicists responsible for the theories and experiments, may understand "observer" as "Human being, with a conciousness".
I'm just a layman with a layman's understanding of quantum shenannigans, but.... am I too far off here?
> some entity that irrevocably changes state because of the quantum events
Yes, "observer" is ambiguous at best.
One query with your proposed definition is: what do you mean by "irrevocable"? If you believe that the quantum state (wavefunction) is objective and independent - and does not collapse but evolves reversibly according to the Schrodinger equation - then nothing is irrevocable, it's just a technical challenge of "can we reverse the evolution of this patch of the universe". Yes, there is this decoherence process, but even that is reversible if you expand your "patch of the universe" sufficiently.
Not many famous physicists believe human consciousness is required for a physical quantum collapse process to occur. John Bell put it nicely:
> Was the wave function waiting to jump for thousands of millions of years until a single-celled living creature appeared? Or did it have to wait a little longer for some highly qualified measurer—with a PhD?
You might be interested to know that people have wondered about what happens if you replace the cat by something that is definitely an "observer": https://en.wikipedia.org/wiki/Wigner%27s_friend . Until the friend (F) tells Wigner (W) the outcome that he experienced when measuring a photon (P), then Wigner supposes that F is quantum entangled with P, i.e. they are in a joint superposition of states. However, the friend supposes that P is in a definite state.
And thanks for engaging with the question. Another problem I have with this is I never see this problems spelled out.
It's hard to tell, with such difficult subjects, the difference between "I don't know" and "Nobody knows".
On top of that, people like to pretend they know. And some other people do really believe they know even if they don't, just because they know a dictionary definition, or something.
That's exactly the point: to frame the "experiment" in a way that only admits the viewpoint of the framer. The only value is to analize why it's impossible to make it a real experiment.
> Edit-> please, think about this: can the "result" of any thought experiment be surprising, not what you expected?
The thought experiment is not to produce a new artefact that you would traditionally call "a result", like a table of subjects responses, or a histogram of responses, etc.
It's to make the researcher consider stuff that cannot be tested, but might be feasible.
> how the setup makes no sense at all because, for starters, there's no way to make a real experiment that's truly equivalent.
That's the whole point. If you can make a real experiment, then it's not a real thought-experiment, is it? The article actually addresses this:
> But this issue need not concern us, because philosophical thought experiments depend on logical coherence rather than practical feasibility.
IOW, it depends on the argument being logically sound, not practically proven.
I do know what a thought experiment is. What I'm trying to point is that they never are really useful because the very reason that makes them unpractical is the reason that make them invalid. That reason is often shadowed by other reasons, but it's the fundamental flaw.
You can turn that around: the differences between the reality and the alternate reality in which the "experiment" is possible are the key to the question.
> I do know what a thought experiment is. What I'm trying to point is that they never are really useful because the very reason that makes them unpractical is the reason that make them invalid. That reason is often shadowed by other reasons, but it's the fundamental flaw.
I understand, but ... you don't judge whether something is useful (or not) according to some arbitrary goal, you judge based on the specific goal intended.
In this case, the goal is "Does the process result in further lines of thought to exhaust, or further discussion?".
I mean, you wouldn't call a brain-storming session useless if it resulted in a conclusion of "no practical implementation is feasible at this time", would you?
All conclusions drawn from “imagine shining a flashlight on a train riding close to the speed of light” revolutionized physics, so the answer is a very clear YES.
That's absolutely not correct. There are real experiments to prove Special Relativity and it has been corroborated multiple times.
The train is only a way to explain it, not a thought experiment. Actually, some equivalent experiments to that are not just possible, but has been executed.
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?
> 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?
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.
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.
> 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.
While I generally think Mary's room doesn't prove anything, it's not strictly nonsense as a thought experiment, it only seems like nonsense if you already assume that everything can be described by a physical theory. Then of course vision and feelings and all of our experiences must be physical. The point of Mary's room is to test the plausibility of this assertion.
It seems very implausible to many people that anyone studying physics, biology and anatomy for any length of time in a black and white room would ever truly understand the experience of colour. Or as another example, do you think studying physics for any length of time will yield an understanding of what it's like to ride a thrilling rollercoaster or sky dive? Doesn't it seem somewhat plausible that such descriptions wouldn't be able to capture something about those experiences?
There are a number of possible responses to such challenges. One is to say that experiencing redness is not actually knowledge but an ability, so no amount of factual study will yield competency, only exposure will (like riding a bike).
Another is as you sort of implicitly assert, is that the very question assumes a kind of infinite knowledge, which humans are terrible at reasoning about. Mary would be able to describe what she'd say in response to any question about colour, but she wouldn't actually understand her answers? This is the kind of paradox that hints at a poorly formed question.
There are plenty more, but the point is that there's something interesting being discussed here, and we're not yet sure what it is, so the thought experiment currently only serves to identify what camp you belong to, ie. strict physicalists, or dualists, or epiphenomenalists, etc.
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).
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.
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?
Right. It's very similar to Bishop Berkeley's argument for idealism, in that the thought experiment doesn't make sense unless you assume a priori that physicalism is false.
> when Mary sees a red apple for the first time, some optical/neural pathways get excited that weren't before
Not necessarily. By hypothesis, Mary has complete knowledge of all the physical facts. That includes the knowledge of how to cause her optical/neural pathways to be excited in the particular way that corresponds to "seeing red" even without the corresponding external stimuli being present. So she could have caused herself to see red. (We might describe this in more conventional language as Mary imagining seeing red, and her complete knowledge of all physical facts giving her powers of imagination far in excess of those of ordinary humans.)
> That includes the knowledge of how to cause her optical/neural pathways to be excited in the particular way that corresponds to "seeing red" even without the corresponding external stimuli being present.
Having knowledge and actually doing it are trivially different things (try sex: knowledge of sex and doing the deed are vastly different things).
Now, if she exercises her knowledge by stimulating her optic nerves, that's the same as seeing the apple. But that's not just "reading about it", it's a physical act of doing!
> Having knowledge and actually doing it are trivially different things
This is a circular argument. You are arguing that Mary does not know what it is like to see red by assuming that she does not know what it is like to see red.
> if she exercises her knowledge by stimulating her optic nerves
Which, since she has complete knowledge of all physical facts, she can do. The thought experiment does not say she "reads about" color vision. It says she has complete knowledge of all physical facts. The article referenced here does not do a good job of describing Jackson's actual thought experiment, but Jackson's actual thought experiment is based on the (extremely strong and unrealistic) premise I have just stated. It has to be, because any weaker premise cannot possibly ground a conclusion that Mary learns something non-physical when she sees the apple. Just saying that Mary knows everything that can be learned by reading about things is not enough; there are many physical facts that cannot be learned by reading.
It's not circular reasoning: it's a rejection of the premise which I can easily dispute: knowing everything there is to know about sex without actually practicing it is not the same as having sex. If someone subjected a brain in a vat with electrical stimulation to make it believe it's having sex (with phantom body parts it doesn't actually possess), then that is indistinguishable from actual sex -- but note how the postulation of the actual Mary experiment steers clear of actually asserting this, and instead claims she "learns the physical properties" of seeing colors.
I realize Jackson is a professor and I'm not, and that this is a well known thought experiment, but I deem it so obviously invalid -- or rather, based on false premises -- that it's not worth considering.
Of course I'm basing my opinion on TFA, but reading Wikipedia's summary I see other philosophers have poked holes on this experiment and even agree with me the premises are false.
P.S. defining "knowing everything there is to know" the same as "physically experiencing" is circular reasoning, and I definitely disagree with this premise.
> knowing everything there is to know about sex without actually practicing it is not the same as having sex.
Your premise only seems plausible as you state it because you are not actually considering the implications of knowing everything there is to know about sex. But knowing everything there is to know about sex includes knowing what it is like to have sex. So the real premise you should be stating is that it is not possible to know everything there is to know about sex if you have not actually had sex.
And, as you appear to realize, making the appropriate adjustment in how the premise of Jackson's Mary thought experiment is interpreted makes it obvious that the argument is invalid--and I agree that it is.
> That includes the knowledge of how to cause her optical/neural pathways to be excited in the particular way that corresponds to "seeing red" even without the corresponding external stimuli being present.
Yes, Mary would have the knowledge of how to perform surgery on herself to stimulate her brain or optic nerves in the right way to generate the necessary experience. I don't think that's within bounds of the thought experiment though.
The thought experiment is testing our intuition about whether third-party objective facts, as found in science, can suffice to describe even subjective experiences like redness. If you need to actually stimulate the experience to gain that understanding, then that either proves that third-party objective facts are not sufficient, or it proves that such experiences are not knowledge.
That's one standard response: knowledge and ability are not equivalent. Someone who had their legs amputated ostensibly knows how to walk but lacks the ability to do so. In principle, no amount of knowledge by itself will make you walk, but knowledge can give you back the ability to walk, ie. a gene therapy with stem cells to grow back limbs, prosthetics, etc.
> I don't think that's within bounds of the thought experiment though.
Why not? The point of the thought experiment is supposed to be to prove that Mary learns something she didn't know before when she sees the apple. But if the premises of the thought experiment give her the ability to give herself that knowledge beforehand, that undermines the conclusion.
> The thought experiment is testing our intuition about whether third-party objective facts, as found in science, can suffice to describe even subjective experiences like redness.
No, it's not. It's claiming to prove that subjective experience cannot be physical, i.e., that physicalism is false. It is making use of a common intuition that subjective experiences are fundamentally different from "third-party objective facts" (Dennett calls it an "intuition pump" for this reason), but that is not a proof of anything, it's just a circular argument, assuming what it purports to prove.
> If you need to actually stimulate the experience to gain that understanding, then that either proves that third-party objective facts are not sufficient, or it proves that such experiences are not knowledge.
Neither one of these refutes physicalism, however, since the process of giving yourself the required stimulus based on your knowledge is a physical process--at least, there is nothing in the premises of the thought experiment that rules that out.
> But if the premises of the thought experiment give her the ability to give herself that knowledge beforehand, that undermines the conclusion.
No it doesn't, it's called the Knowledge Argument because the knowledge of redness purportedly does not deductively follow from the knowledge of any amount of physical facts. It requires non-deductive steps, like surgery and brain stimulation in this case.
You might as well say that Mary could construct a red LED and gain the knowledge of redness that way, because that too is a physical process. That's obviously out of bounds, and surgery is the same type of invalid move.
Edit:
> Neither one of these refutes physicalism, however, since the process of giving yourself the required stimulus based on your knowledge is a physical process--at least, there is nothing in the premises of the thought experiment that rules that out.
Under dualism, physical processes are correlated with non-physical qualia, so triggering the physical process in a roundabout way is not a valid move here. The question being tested is whether knowledge of redness follows from knowledge of all other physical facts, not whether knowledge of redness follows from triggering a physical process because we already know that does.
> the knowledge of redness purportedly does not deductively follow from the knowledge of any amount of physical facts.
Which is just a bare assertion, not an argument. Nothing in the premises of Jackson's thought experiment entails this or requires it. To a physicalist, knowledge of redness is knowledge of a physical fact, so this statement is simply false.
> surgery is the same type of invalid move
If you're hung up on the word "surgery", then eliminate it: it's just as possible that Mary could simply imagine, based on her complete knowledge of all physical facts, what it would be like for her to see red, without having to do any surgery at all. You might say this is implausible, but so is the premise that Mary has complete knowledge of all physical facts. But that's the premise of the thought experiment.
> Under dualism
Jackson's thought experiment does not prove that dualism must be true. Nor can you assume that dualism is true as a premise, since that is just a circular argument. A physicalist, like me, simply does not think dualism is true, and it is no argument against that to show what would be the case if dualism were true. You need to argue, from premises that don't already contain dualism, that dualism must be true. Jackson didn't do that. Nor do any of the other arguments described in the article, including the Knowledge Argument.
You're not telling me anything I don't already know about physicalism or Mary's room. What's in dispute here is whether any physical action is a legitimate answer to the Knowledge Argument, so I'm going to ignore the rest and focus on this disagreement:
"Imagining" is not the same as surgery. Do you agree or disagree that Mary constructing a red LED to experience redness is not a legitimate response to the Knowledge Argument?
> Do you agree or disagree that Mary constructing a red LED to experience redness is not a legitimate response to the Knowledge Argument?
It depends on what you think the Knowledge Argument is supposed to prove.
If you think the Knowledge Argument is supposed to prove that physicalism is false, then I disagree. To refute physicalism, it is pointless to say that some physical processes are not "knowledge". Even if the physicalist agrees, that in no way refutes physicalism. The physicalist simply says that the processes that Mary induces in her brain by constructing a red LED (or doing surgery on her optic nerve, or just imagining what seeing red would be like), even if they are not "knowledge", are still physical processes, and that those physical processes are Mary's experience of seeing red. Nothing in the Knowledge Argument refutes that.
If you think the Knowledge Argument is supposed to prove that there are physical things that aren't "knowledge" (whether or not there are also non physical things is then a separate question), then I neither agree nor disagree as a matter of physics, since what we use the word "knowledge" to refer to is a matter of definitions of words, not physics. I have no problem with accepting your definition of the word "knowledge" for purposes of this discussion. I just don't think accepting that definition says anything about whether or not physicalism is true.
> The physicalist simply says that the processes that Mary induces in her brain by constructing a red LED (or doing surgery on her optic nerve, or just imagining what seeing red would be like), even if they are not "knowledge", are still physical processes
This isn't relevant. Nobody is really disputing that physical processes cause qualia. You don't see the redness of an apple until the apple actually enters your visual field. Cause=physical event, result=qualia. Even dualists agree with this.
Therefore the Knowledge Argument is not about whether any physical process is causally linked to qualia, it's specifically about whether qualia can be deduced only from factual knowledge, because under physicalism, all facts are physical facts.
If physicalism is true, then all facts are third-party objective physical facts. Therefore quale are physical facts. If given an understanding of all physical facts, then Mary should be able to deduce her quale. If she cannot deduce her quale (or it seems very implausible), then either some mistake has been made or physicalism is false. Where is the mistake?
You cannot answer this question by saying her knowledge gives her the ability to trigger the usual physical process to cause qualia, because the question is about the deduction. The only outcomes of this thought experiment are one of: 1. denying that physicalism is true, or 2. denying that quale are facts, 3. accepting that Mary would be able to deduce her quale, 4. concluding that the thought experiment contains some inherent contradiction.
> The only outcomes of this thought experiment are one of: 1. denying that physicalism is true, or 2. denying that quale are facts, 3. accepting that Mary would be able to deduce her quale, 4. concluding that the thought experiment contains some inherent contradiction.
No, you left out one:
5. Denying that there is any difference, from the standpoint of testing whether physicalism is true or false, between Mary "deducing" her quale and Mary "triggering" her quale with a red LED or surgery or by imagining.
Basically you are trying to make an argument by redefining words to make arbitrary distinctions that don't have any bearing on whether physicalism is true or false. First you want to limit what Mary has to "knowledge", but nothing in physicalism requires all physical things to be "knowledge" or requires that all physical things must be reachable from "knowledge". Then you want to limit Mary to only having "factual knowledge", but nothing in physicalism requires all physical things to be "factual knowledge" or to be reachable from "factual knowledge". Then you want to limit Mary to only having "third-party objective physical facts", but nothing in physicalism requires that all physical things are "third-party objective physical facts". Then you want to limit Mary to only be able to "deduce" her quale instead of triggering it or imagining it, but nothing in physicalism requires someone to have to "deduce" their quale in order to know what it is like without having been subjected to the normal external stimulus (in this case the image of a red apple on Mary's retina) that would trigger it. Physicalism simply does not make or require any of these distinctions you keep making.
The claim of physicalism is simple: Mary's quale "seeing red" is a physical thing. (Or "process", or "fact", or whatever you want to call it; the substance of the claim remains the same.) The only way to disprove that would be to show that her quale being a physical thing somehow leads to a contradiction. The Knowledge Argument does not do that. It does not even claim to do that. It simply constructs a straw man version of "physicalism" that is vulnerable to refutation by this particular argument even though actual physicalism is not.
When you look at what physicalism actually says, the so-called Knowledge Argument boils down to a bare assertion. The premise is that Mary has all the physical information. The claim is that she learns something when she sees the red apple, implying that she did not have the information about what it would be like to see the apple beforehand, when she had all the physical information. But the claim simply does not follow from the premise; it is a non sequitur. The only way to get to the claim from the premise is to add an additional premise that having all the physical information does not include having the information about what it is like to see the red apple. But of course that is just arguing in a circle; it is simply assuming that physicalism is false in order to "prove" that physicalism is false.
The whole point of physicalism is that having all the physical information is having all the information, so it includes knowing what it is like to see red, to taste wine, to feel the sun shining on you, etc., etc., etc.. So any thought experiment that claims that Mary, who has all the physical information, will learn something when she sees the red apple is simply based on a false premise according to physicalism. Which makes it obvious that no such argument can refute physicalism.
> Basically you are trying to make an argument by redefining words to make arbitrary distinctions that don't have any bearing on whether physicalism is true or false.
No, this is a well studied problem by thousands of philosophers over 40 years. Maybe reconsider your position that you understand this argument better than they do. I don't see any benefit in continuing this discussion at this point.
> No, this is a well studied problem by thousands of philosophers over 40 years. Maybe reconsider your position that you understand this argument better than they do.
Ah, the old argument from authority. Sorry, not buying it.
> I don't see any benefit in continuing this discussion at this point.
If Mary had (and had the capacity to conpletely analyze) all data on all physical processes in the universe, she could deduce her, and all other, qualia.
That Mary has all factual knowledge is a premise, the conclusion that she could deduce her qualia does not necessarily follow, and you have provided no proof demonstrating that it follows
> That Mary has all factual knowledge is a premise, the conclusion that she could deduce her qualia does not necessarily follow
It's not a conclusion; to a physicalist, it's part of the premise, since knowledge of her qualia is "factual knowledge". You can't just declare by fiat that this is false; that's a circular argument, as I have already said multiple times.
> you have provided no proof
The burden of proof is on you, not me; if you want to make an argument based on the claim that knowledge of qualia is not "factual knowledge", then you have to prove that it isn't. You can't just declare it by fiat.
I understand that non-physicalists, like you and Jackson, believe that knowledge of qualia is not "factual knowledge". But physicalists, like me and Dennett, disagree. Given that disagreement, you can't make your belief a premise of an argument and expect me to accept it. All you're doing is restating your position. Fine, I understand that's your position. But it's not the same as giving an actual argument for it based on premises that I must accept.
I absolutely have a problem with considering "imagining" (especially something you've never experienced before) the same as "experiencing". I'm sorry, but giving Mary such superpowers completely invalidates the experiment for me.
It sounds too much of the old Maths joke: "let's consider a spherical cow."
> giving Mary such superpowers completely invalidates the experiment for me
This complaint should be addressed, not to me, but to Jackson, whose premise for the thought experiment gives Mary such "superpowers". I agree that such a premise is completely unrealistic and invalidates the thought experiment. Unfortunately many philosophers do not appear to have gotten the memo.
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!
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/S089360801...
That's all true, but that's not what the thought experiment is about. The thought experiment states that not only has Mary read everything there is about colour vision, but that she knows everything there is to know.
Yes, it hinges on the definition of "to know everything about something" as if there are neatly defined epistemic boundaries. Not all knowledge can be captured in words. Also, this assumes that all knowledge can exist independent of perspectives.
No.
There are qualia that are necessarily unique (because our constellation of experiences that generate these is unique) that we do not have shared definitions -- which is what words are. To then say that one can "know everything" is meaningless. It's generally the case with these seeming conundrums. The fault lies in the most basic of assumptions that are almost invisible to us because they rely on our intuition.
> Does the person who has read absolutely everything about love, know what it feels like to love?
No, but Mary knows much more than that. By hypothesis, Mary has complete knowledge of all physical facts. That is vastly more knowledge than a person can gain by reading "absolutely everything" about anything.
One big problem with the thought experiment is that the premise is so outlandish that almost nobody is willing to use it as given in their reasoning, including Jackson himself. Instead they substitute some vastly weaker premise and ignore the vast difference in implications.
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?
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.
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?
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)
> 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”.
No, it doesn't. Physicalism does not require that the exact same brain state must accompany a particular perception, either in different humans, or in the same human at different times. All it requires is that perception is a physical process.
> 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.
And the physicalist's response is that even if this is true, it does not refute physicalism. Perception can be a physical process and still satisfy these statements.
Thanks for the clarification! I find this topic fascinating, but am definitely still learning it.
My impression was that the underlying assumption (or at least, the end goal) of the physicalist interpretation is that this physical process can ultimately be used to predict how consciousness arises. But if there is no expectation of similar patterns across individuals, I would imagine the usefulness in that sense is limited. So, perhaps this isn't an end goal of physicalism.
In which case, perhaps neither party expects there to be a solution to the origins of consciousness, maybe!
> My impression was that the underlying assumption (or at least, the end goal) of the physicalist interpretation is that this physical process can ultimately be used to predict how consciousness arises.
This is the hope of many physicalists, but it is not required for physicalism to be true.
This is a circular argument: you are arguing that physicalism is not true by assuming that physicalism (which asserts that there is only one knowledge domain) is not true.
According to a physicalist, perception is a physical process. So are knowing and experiencing and "what it is like". So to a physicalist, someone who, like Mary in the thought experiment, is stipulated to have complete knowledge of all of the physical facts will know "what it is like" to have any perception, because that is part of the physical facts. The only difference is that Mary, before she is released from the room, knows what it is like to see red by a process of deduction--by looking at what physical facts, among those she knows, correspond to her seeing red--instead of by the more usual process of having her retina and optic nerve stimulated in a particular way.
To put it another way, Mary, unlike you and me, knows what it is like to see red by imagining it, based on her complete knowledge of all the physical facts. That complete knowledge allows her to put her brain into any state she likes, even in the absence of the external stimuli that would normally be present. Sure, this is farfetched, but so is the premise that Mary has complete knowledge of all the physical facts. But if you grant the premise, you are granting Mary the powers she needs to do the thing that Jackson incorrectly claims she cannot do.
> 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
First, seeing red is obviously not irrelevant to Mary, so this argument says nothing about Mary.
But second, if the alien has complete knowledge of all the physical facts about human brains, bodies, etc., then seeing the color red is not irrelevant to the alien, because seeing the color red is part of the physical facts that the alien knows. In other words, this hypothetical alien knows things that any "normal" alien would not know, and that changes what is "relevant" to this alien.
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.
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.
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.
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.
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.)
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.
> And suppose Mr. Chav has grown up in England, but is uneducated and isn't even sure who is the Prime Minister.
Easy: The head of lettuce.
More seriously, this stuff comes up with historical events, which is only to be expected given that the human mind is a tale-spinner of ill repute that has a habit of creating and re-creating stories and convincing itself that this new version was the way it really happened. Records might be incomplete, or even wrong, but they don't flip things around quite as avidly as the human mind. Of course, I don't know how much known facts about cognitive science are allowed to inform philosophy...
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.
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[ 3.1 ms ] story [ 264 ms ] thread[1] https://www.wtamu.edu/~cbaird/sq/2020/02/11/do-blind-people-...
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.
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.
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.
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.
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?
What do you think?
A conceptual framework for consciousness, https://www.pnas.org/doi/10.1073/pnas.2116933119#fig01
I've heard Joshua Bach talk in similar terms and I frankly do not get it.
The paper goes over that too: 1. The brain uses information to build models, 2. all brain models are necessarily inaccurate.
Therefore quale are inaccurate models of perceptions and/or models of perceptual memory, where some information has been thrown away, as we do with all models. The redness of an apple is a distorted sense memory of the apple, just with all the "appleness" thrown away leaving only the "redness", which is why they seem so vague and ephemeral.
I'm pretty sure I'm missing the main point of the paper and I'll read it again tomorrow.
If I and some other people would follow a certain algorithm, the one in the paper, but refined and perfected for a thousand years... Calculating with pen and paper the progression of states from a suitable initial state... Would an illusion of experience/qualia appear somewhere just from our calculations? Would it feel like something to be the state represented in the numbers?
Anyway, thanks for the discussion.
No, why would some data scribbled on paper describing qualia in a model of a brain reproduce that qualia in your brain?
If you write code on a piece of paper, does your laptop suddenly execute that code? If your laptop takes a picture of that scribbled code, does it then execute that code? If you take a picture of it and then OCR it, does it execute that code? If you take a picture of it, OCR it, and then feed it to the right compiler/runtime does it execute the code?
As you can see, there are numerous layers of translation to get the information in the right form and in the right place. "The right form" for our qualia is the form we evolved to perceive. I'm not sure why one would expect information in any other form to produce quale.
Then yes. As I said, quale are sort of information stripped models of our perceptions, but divorced from direct perception, and this lack of a direct link is why they seem ephemeral and mysterious. If you believe perceptions have a formal model then quale are a projection of those.
And this is the hard problem of consciousness, how it is even possible to evolve that. The rest is the easy problem of consciousness.
How was it possible for the eye to evolve? The paper I linked goes over this too: systems that have attention schema models are more efficient and more effective than those that don't.
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.
That's fun! To me apples are green by default. How many people have you asked? (Just curious)
If you said imagine a good tasting apple I would envision something colored like a honeycrisp. Or an apple pie apple being green.
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?
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.
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.
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".
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.
Which leads us to the interesting conclusion "you can experience everything without actually experiencing it" which is a bit Buddhist.
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.
Yes.
> 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?
No. If you submerge your hand in mercury you will not get wet. The same if you coat you hand in aerogel. It is empirical fact that people do not describe this situations as being wet.
E.g.: https://youtu.be/GcdB5bFwio4?t=225
Then, having worn a nitrile glove while putting my hand in water before, I doubt that Bob would experience wetness.
Easily tested at home.
The glove provides quite a good approximation.
Tangent: To what extent is that evolutionary? Wetness being a unique feeling could be, that we have evolved a greater sensory capacity to experience water, due to its abundance and importance.
Thus other words for touch (in English) generalise across a variety of sensory experiences (sticky, slimy, hard, etc.) where as wetness is specific to fluids that behave like water.
If I had a point, I guess it would be that maybe wetness is a especially unique experience. I don’t know whether this makes it a better or worse example to use.
For your second thought experiment, I would argue that wearing a wet glove is not a complete representation of wetness, because of the specific interactions that wetness has on the skin; apart from the sensations of pressure and heat loss, there is also the way that water moves/interacts with the skin making it more grippy, the texture of water and it's surface tension forming drips, and the movement of those drips, and the way wet skin feels different are all part of the overall qualia of wetness, hence why we differentiate between e.g. drenched and misted. There are 6 different mechanoreceptor systems in the skin, and the complete phenomenal concept of wetness likely involves all of them. I also think this is a poor thought experiment, because it necessarily involves water, image Bob exists in a plane of reality without liquid water entirely, would it be feasible for him to experience wetness?
I don't really object to that. My conclusion is that you can know what red is on the level of qualia without getting in contact with approximately red wavelength light. You can know what sound is without getting in contact with pressure waves. You can know what wetness is without getting in direct contact with water.
> I also think this is a poor thought experiment, because it necessarily involves water, image Bob exists in a plane of reality without liquid water entirely, would it be feasible for him to experience wetness?
I don't know. In that plane of reality we would not have evolved a mechanism for sensing wetness.
I don't know if it's possible to experience being in a spacial 2 dimensional reality or spacial 4 dimensional reality. My guess would be yes, but it would require significant alternations to our bodies, mostly brain structures.
Our experience of reality is almost certainly very limited vs. what's possible. There exist distinct human personalities who can see trough each other eyes and communicate with their minds - I'm talking about craniopagus twins.
I'm looking forward to high-bandwidth computer-brain interfaces. Some people may actually get to experience how it is to be a computer or whether it feel like anything at all.
As such, I find it entirely plausible that Mary would be too old to learn color vision. Much like people born blind cannot acquire full vision later. She might just be unable to experience red. That would include her dreams.
Yes stimulatimg her optical nerves could prepare her to see red. Meaning she'd jave the brain hooked up the right way to see it.
It doesn't. When you dig into the details, Jackson's argument is circular: he can only infer that Mary learns something new by implicitly assuming it.
This is indeed one of the standard responses to Mary's Room, where experiences like "redness" are not actually knowledge but are an "ability". So Mary doesn't actually "learn" anything new technically, but she acquires a new ability to experience redness when exposed to it for the first time.
Unless they're dyslexic, right?
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?
Isn't all of mathematics just thought experiments? No shortage of surprising results there.
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.
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.
The core of Mary's adventures is a false dicotomy: that matter is the only component of physical reality. But processes, structure and energy flow are as real as matter. Actually, at a very small scale, matter seems to be exactly that.
So as usual with all these dualism "enigmas", the only problem is starting from an old perspective that doesn't play well with current knowledge.
Consciousness seems to be a complex physical process seen from inside itself. There's no mistery or toughness in that, except that we can't compare it with anything else.
We can't use the inside and ouside outlooks at the same time. But Wittgenstein already stated that more than a century ago.
I always assumed everybody understood "observer" to be shorthand for "some entity that irrevocably changes state because of the quantum events", but I'm starting to realize that lots of people, even the famous physicists responsible for the theories and experiments, may understand "observer" as "Human being, with a conciousness".
I'm just a layman with a layman's understanding of quantum shenannigans, but.... am I too far off here?
Yes, "observer" is ambiguous at best.
One query with your proposed definition is: what do you mean by "irrevocable"? If you believe that the quantum state (wavefunction) is objective and independent - and does not collapse but evolves reversibly according to the Schrodinger equation - then nothing is irrevocable, it's just a technical challenge of "can we reverse the evolution of this patch of the universe". Yes, there is this decoherence process, but even that is reversible if you expand your "patch of the universe" sufficiently.
Not many famous physicists believe human consciousness is required for a physical quantum collapse process to occur. John Bell put it nicely:
> Was the wave function waiting to jump for thousands of millions of years until a single-celled living creature appeared? Or did it have to wait a little longer for some highly qualified measurer—with a PhD?
You might be interested to know that people have wondered about what happens if you replace the cat by something that is definitely an "observer": https://en.wikipedia.org/wiki/Wigner%27s_friend . Until the friend (F) tells Wigner (W) the outcome that he experienced when measuring a photon (P), then Wigner supposes that F is quantum entangled with P, i.e. they are in a joint superposition of states. However, the friend supposes that P is in a definite state.
Very good point, who knows! I guess whatever the universe can't pretend didn't happen, like a photon being absorbed and re-emited by an electron.
Which, what does that even mean? I don't know! Does anyone? I don't know!
It's hard to tell, with such difficult subjects, the difference between "I don't know" and "Nobody knows".
On top of that, people like to pretend they know. And some other people do really believe they know even if they don't, just because they know a dictionary definition, or something.
Not necessarily for the framer of the experiment, but that's not the point - it's to get other people to think about a problem in a different way.
The thought experiment is not to produce a new artefact that you would traditionally call "a result", like a table of subjects responses, or a histogram of responses, etc.
It's to make the researcher consider stuff that cannot be tested, but might be feasible.
> how the setup makes no sense at all because, for starters, there's no way to make a real experiment that's truly equivalent.
That's the whole point. If you can make a real experiment, then it's not a real thought-experiment, is it? The article actually addresses this:
> But this issue need not concern us, because philosophical thought experiments depend on logical coherence rather than practical feasibility.
IOW, it depends on the argument being logically sound, not practically proven.
You can turn that around: the differences between the reality and the alternate reality in which the "experiment" is possible are the key to the question.
I understand, but ... you don't judge whether something is useful (or not) according to some arbitrary goal, you judge based on the specific goal intended.
In this case, the goal is "Does the process result in further lines of thought to exhaust, or further discussion?".
I mean, you wouldn't call a brain-storming session useless if it resulted in a conclusion of "no practical implementation is feasible at this time", would you?
The train is only a way to explain it, not a thought experiment. Actually, some equivalent experiments to that are not just possible, but has been executed.
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?
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.
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.
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.
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/
It seems very implausible to many people that anyone studying physics, biology and anatomy for any length of time in a black and white room would ever truly understand the experience of colour. Or as another example, do you think studying physics for any length of time will yield an understanding of what it's like to ride a thrilling rollercoaster or sky dive? Doesn't it seem somewhat plausible that such descriptions wouldn't be able to capture something about those experiences?
There are a number of possible responses to such challenges. One is to say that experiencing redness is not actually knowledge but an ability, so no amount of factual study will yield competency, only exposure will (like riding a bike).
Another is as you sort of implicitly assert, is that the very question assumes a kind of infinite knowledge, which humans are terrible at reasoning about. Mary would be able to describe what she'd say in response to any question about colour, but she wouldn't actually understand her answers? This is the kind of paradox that hints at a poorly formed question.
There are plenty more, but the point is that there's something interesting being discussed here, and we're not yet sure what it is, so the thought experiment currently only serves to identify what camp you belong to, ie. strict physicalists, or dualists, or epiphenomenalists, etc.
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).
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.
If Mary knows everything there is to know about colour vision, that includes knowing the experience of seeing the colour red.
If she doesn't know that, it simply contradicts the premise.
If so, duly noted.
Not necessarily. By hypothesis, Mary has complete knowledge of all the physical facts. That includes the knowledge of how to cause her optical/neural pathways to be excited in the particular way that corresponds to "seeing red" even without the corresponding external stimuli being present. So she could have caused herself to see red. (We might describe this in more conventional language as Mary imagining seeing red, and her complete knowledge of all physical facts giving her powers of imagination far in excess of those of ordinary humans.)
Having knowledge and actually doing it are trivially different things (try sex: knowledge of sex and doing the deed are vastly different things).
Now, if she exercises her knowledge by stimulating her optic nerves, that's the same as seeing the apple. But that's not just "reading about it", it's a physical act of doing!
This is a circular argument. You are arguing that Mary does not know what it is like to see red by assuming that she does not know what it is like to see red.
> if she exercises her knowledge by stimulating her optic nerves
Which, since she has complete knowledge of all physical facts, she can do. The thought experiment does not say she "reads about" color vision. It says she has complete knowledge of all physical facts. The article referenced here does not do a good job of describing Jackson's actual thought experiment, but Jackson's actual thought experiment is based on the (extremely strong and unrealistic) premise I have just stated. It has to be, because any weaker premise cannot possibly ground a conclusion that Mary learns something non-physical when she sees the apple. Just saying that Mary knows everything that can be learned by reading about things is not enough; there are many physical facts that cannot be learned by reading.
I realize Jackson is a professor and I'm not, and that this is a well known thought experiment, but I deem it so obviously invalid -- or rather, based on false premises -- that it's not worth considering.
Of course I'm basing my opinion on TFA, but reading Wikipedia's summary I see other philosophers have poked holes on this experiment and even agree with me the premises are false.
P.S. defining "knowing everything there is to know" the same as "physically experiencing" is circular reasoning, and I definitely disagree with this premise.
Your premise only seems plausible as you state it because you are not actually considering the implications of knowing everything there is to know about sex. But knowing everything there is to know about sex includes knowing what it is like to have sex. So the real premise you should be stating is that it is not possible to know everything there is to know about sex if you have not actually had sex.
And, as you appear to realize, making the appropriate adjustment in how the premise of Jackson's Mary thought experiment is interpreted makes it obvious that the argument is invalid--and I agree that it is.
Yes, Mary would have the knowledge of how to perform surgery on herself to stimulate her brain or optic nerves in the right way to generate the necessary experience. I don't think that's within bounds of the thought experiment though.
The thought experiment is testing our intuition about whether third-party objective facts, as found in science, can suffice to describe even subjective experiences like redness. If you need to actually stimulate the experience to gain that understanding, then that either proves that third-party objective facts are not sufficient, or it proves that such experiences are not knowledge.
That's one standard response: knowledge and ability are not equivalent. Someone who had their legs amputated ostensibly knows how to walk but lacks the ability to do so. In principle, no amount of knowledge by itself will make you walk, but knowledge can give you back the ability to walk, ie. a gene therapy with stem cells to grow back limbs, prosthetics, etc.
So the idea is that experiencing redness is not knowledge but an ability you acquire by exposure to colours: https://en.wikipedia.org/wiki/Knowledge_argument#Ability_hyp...
Why not? The point of the thought experiment is supposed to be to prove that Mary learns something she didn't know before when she sees the apple. But if the premises of the thought experiment give her the ability to give herself that knowledge beforehand, that undermines the conclusion.
> The thought experiment is testing our intuition about whether third-party objective facts, as found in science, can suffice to describe even subjective experiences like redness.
No, it's not. It's claiming to prove that subjective experience cannot be physical, i.e., that physicalism is false. It is making use of a common intuition that subjective experiences are fundamentally different from "third-party objective facts" (Dennett calls it an "intuition pump" for this reason), but that is not a proof of anything, it's just a circular argument, assuming what it purports to prove.
> If you need to actually stimulate the experience to gain that understanding, then that either proves that third-party objective facts are not sufficient, or it proves that such experiences are not knowledge.
Neither one of these refutes physicalism, however, since the process of giving yourself the required stimulus based on your knowledge is a physical process--at least, there is nothing in the premises of the thought experiment that rules that out.
No it doesn't, it's called the Knowledge Argument because the knowledge of redness purportedly does not deductively follow from the knowledge of any amount of physical facts. It requires non-deductive steps, like surgery and brain stimulation in this case.
You might as well say that Mary could construct a red LED and gain the knowledge of redness that way, because that too is a physical process. That's obviously out of bounds, and surgery is the same type of invalid move.
Edit:
> Neither one of these refutes physicalism, however, since the process of giving yourself the required stimulus based on your knowledge is a physical process--at least, there is nothing in the premises of the thought experiment that rules that out.
Under dualism, physical processes are correlated with non-physical qualia, so triggering the physical process in a roundabout way is not a valid move here. The question being tested is whether knowledge of redness follows from knowledge of all other physical facts, not whether knowledge of redness follows from triggering a physical process because we already know that does.
Which is just a bare assertion, not an argument. Nothing in the premises of Jackson's thought experiment entails this or requires it. To a physicalist, knowledge of redness is knowledge of a physical fact, so this statement is simply false.
> surgery is the same type of invalid move
If you're hung up on the word "surgery", then eliminate it: it's just as possible that Mary could simply imagine, based on her complete knowledge of all physical facts, what it would be like for her to see red, without having to do any surgery at all. You might say this is implausible, but so is the premise that Mary has complete knowledge of all physical facts. But that's the premise of the thought experiment.
> Under dualism
Jackson's thought experiment does not prove that dualism must be true. Nor can you assume that dualism is true as a premise, since that is just a circular argument. A physicalist, like me, simply does not think dualism is true, and it is no argument against that to show what would be the case if dualism were true. You need to argue, from premises that don't already contain dualism, that dualism must be true. Jackson didn't do that. Nor do any of the other arguments described in the article, including the Knowledge Argument.
"Imagining" is not the same as surgery. Do you agree or disagree that Mary constructing a red LED to experience redness is not a legitimate response to the Knowledge Argument?
It depends on what you think the Knowledge Argument is supposed to prove.
If you think the Knowledge Argument is supposed to prove that physicalism is false, then I disagree. To refute physicalism, it is pointless to say that some physical processes are not "knowledge". Even if the physicalist agrees, that in no way refutes physicalism. The physicalist simply says that the processes that Mary induces in her brain by constructing a red LED (or doing surgery on her optic nerve, or just imagining what seeing red would be like), even if they are not "knowledge", are still physical processes, and that those physical processes are Mary's experience of seeing red. Nothing in the Knowledge Argument refutes that.
If you think the Knowledge Argument is supposed to prove that there are physical things that aren't "knowledge" (whether or not there are also non physical things is then a separate question), then I neither agree nor disagree as a matter of physics, since what we use the word "knowledge" to refer to is a matter of definitions of words, not physics. I have no problem with accepting your definition of the word "knowledge" for purposes of this discussion. I just don't think accepting that definition says anything about whether or not physicalism is true.
This isn't relevant. Nobody is really disputing that physical processes cause qualia. You don't see the redness of an apple until the apple actually enters your visual field. Cause=physical event, result=qualia. Even dualists agree with this.
Therefore the Knowledge Argument is not about whether any physical process is causally linked to qualia, it's specifically about whether qualia can be deduced only from factual knowledge, because under physicalism, all facts are physical facts.
If physicalism is true, then all facts are third-party objective physical facts. Therefore quale are physical facts. If given an understanding of all physical facts, then Mary should be able to deduce her quale. If she cannot deduce her quale (or it seems very implausible), then either some mistake has been made or physicalism is false. Where is the mistake?
You cannot answer this question by saying her knowledge gives her the ability to trigger the usual physical process to cause qualia, because the question is about the deduction. The only outcomes of this thought experiment are one of: 1. denying that physicalism is true, or 2. denying that quale are facts, 3. accepting that Mary would be able to deduce her quale, 4. concluding that the thought experiment contains some inherent contradiction.
No, you left out one:
5. Denying that there is any difference, from the standpoint of testing whether physicalism is true or false, between Mary "deducing" her quale and Mary "triggering" her quale with a red LED or surgery or by imagining.
Basically you are trying to make an argument by redefining words to make arbitrary distinctions that don't have any bearing on whether physicalism is true or false. First you want to limit what Mary has to "knowledge", but nothing in physicalism requires all physical things to be "knowledge" or requires that all physical things must be reachable from "knowledge". Then you want to limit Mary to only having "factual knowledge", but nothing in physicalism requires all physical things to be "factual knowledge" or to be reachable from "factual knowledge". Then you want to limit Mary to only having "third-party objective physical facts", but nothing in physicalism requires that all physical things are "third-party objective physical facts". Then you want to limit Mary to only be able to "deduce" her quale instead of triggering it or imagining it, but nothing in physicalism requires someone to have to "deduce" their quale in order to know what it is like without having been subjected to the normal external stimulus (in this case the image of a red apple on Mary's retina) that would trigger it. Physicalism simply does not make or require any of these distinctions you keep making.
The claim of physicalism is simple: Mary's quale "seeing red" is a physical thing. (Or "process", or "fact", or whatever you want to call it; the substance of the claim remains the same.) The only way to disprove that would be to show that her quale being a physical thing somehow leads to a contradiction. The Knowledge Argument does not do that. It does not even claim to do that. It simply constructs a straw man version of "physicalism" that is vulnerable to refutation by this particular argument even though actual physicalism is not.
When you look at what physicalism actually says, the so-called Knowledge Argument boils down to a bare assertion. The premise is that Mary has all the physical information. The claim is that she learns something when she sees the red apple, implying that she did not have the information about what it would be like to see the apple beforehand, when she had all the physical information. But the claim simply does not follow from the premise; it is a non sequitur. The only way to get to the claim from the premise is to add an additional premise that having all the physical information does not include having the information about what it is like to see the red apple. But of course that is just arguing in a circle; it is simply assuming that physicalism is false in order to "prove" that physicalism is false.
The whole point of physicalism is that having all the physical information is having all the information, so it includes knowing what it is like to see red, to taste wine, to feel the sun shining on you, etc., etc., etc.. So any thought experiment that claims that Mary, who has all the physical information, will learn something when she sees the red apple is simply based on a false premise according to physicalism. Which makes it obvious that no such argument can refute physicalism.
No, this is a well studied problem by thousands of philosophers over 40 years. Maybe reconsider your position that you understand this argument better than they do. I don't see any benefit in continuing this discussion at this point.
Ah, the old argument from authority. Sorry, not buying it.
> I don't see any benefit in continuing this discussion at this point.
Neither do I.
No, it's not, it's part of the explicit premise of the thought experiment.
It's not a conclusion; to a physicalist, it's part of the premise, since knowledge of her qualia is "factual knowledge". You can't just declare by fiat that this is false; that's a circular argument, as I have already said multiple times.
> you have provided no proof
The burden of proof is on you, not me; if you want to make an argument based on the claim that knowledge of qualia is not "factual knowledge", then you have to prove that it isn't. You can't just declare it by fiat.
I understand that non-physicalists, like you and Jackson, believe that knowledge of qualia is not "factual knowledge". But physicalists, like me and Dennett, disagree. Given that disagreement, you can't make your belief a premise of an argument and expect me to accept it. All you're doing is restating your position. Fine, I understand that's your position. But it's not the same as giving an actual argument for it based on premises that I must accept.
It sounds too much of the old Maths joke: "let's consider a spherical cow."
This complaint should be addressed, not to me, but to Jackson, whose premise for the thought experiment gives Mary such "superpowers". I agree that such a premise is completely unrealistic and invalidates the thought experiment. Unfortunately many philosophers do not appear to have gotten the memo.
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-... As I mentioned there, I also co-authored a book (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/S089360801...
No, but Mary knows much more than that. By hypothesis, Mary has complete knowledge of all physical facts. That is vastly more knowledge than a person can gain by reading "absolutely everything" about anything.
One big problem with the thought experiment is that the premise is so outlandish that almost nobody is willing to use it as given in their reasoning, including Jackson himself. Instead they substitute some vastly weaker premise and ignore the vast difference in implications.
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.
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?
Yes, she has learned to detect red colour using her eyes.
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.
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?
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)
No, it doesn't. Physicalism does not require that the exact same brain state must accompany a particular perception, either in different humans, or in the same human at different times. All it requires is that perception is a physical process.
> 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.
And the physicalist's response is that even if this is true, it does not refute physicalism. Perception can be a physical process and still satisfy these statements.
My impression was that the underlying assumption (or at least, the end goal) of the physicalist interpretation is that this physical process can ultimately be used to predict how consciousness arises. But if there is no expectation of similar patterns across individuals, I would imagine the usefulness in that sense is limited. So, perhaps this isn't an end goal of physicalism.
In which case, perhaps neither party expects there to be a solution to the origins of consciousness, maybe!
This is the hope of many physicalists, but it is not required for physicalism to be true.
This is a circular argument: you are arguing that physicalism is not true by assuming that physicalism (which asserts that there is only one knowledge domain) is not true.
According to a physicalist, perception is a physical process. So are knowing and experiencing and "what it is like". So to a physicalist, someone who, like Mary in the thought experiment, is stipulated to have complete knowledge of all of the physical facts will know "what it is like" to have any perception, because that is part of the physical facts. The only difference is that Mary, before she is released from the room, knows what it is like to see red by a process of deduction--by looking at what physical facts, among those she knows, correspond to her seeing red--instead of by the more usual process of having her retina and optic nerve stimulated in a particular way.
To put it another way, Mary, unlike you and me, knows what it is like to see red by imagining it, based on her complete knowledge of all the physical facts. That complete knowledge allows her to put her brain into any state she likes, even in the absence of the external stimuli that would normally be present. Sure, this is farfetched, but so is the premise that Mary has complete knowledge of all the physical facts. But if you grant the premise, you are granting Mary the powers she needs to do the thing that Jackson incorrectly claims she cannot do.
> 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
First, seeing red is obviously not irrelevant to Mary, so this argument says nothing about Mary.
But second, if the alien has complete knowledge of all the physical facts about human brains, bodies, etc., then seeing the color red is not irrelevant to the alien, because seeing the color red is part of the physical facts that the alien knows. In other words, this hypothetical alien knows things that any "normal" alien would not know, and that changes what is "relevant" to this alien.
Since Mary knows everything about human physiology and physics, she is able to simulate a neural vision system within her own brain.
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/
[2] https://www.npr.org/2009/09/17/112897277/thanks-to-gene-ther...
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.
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.
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.)
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.
I don't see any issue - both can talk about England and provide different perspectives.
Easy: The head of lettuce.
More seriously, this stuff comes up with historical events, which is only to be expected given that the human mind is a tale-spinner of ill repute that has a habit of creating and re-creating stories and convincing itself that this new version was the way it really happened. Records might be incomplete, or even wrong, but they don't flip things around quite as avidly as the human mind. Of course, I don't know how much known facts about cognitive science are allowed to inform philosophy...
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.