A lot of these arguments don't seem very good. Some of them seem to be arguments based off things that people already agree with you on. Obviously, if zombies are real, then physicalism is false. I guess this would convince people who believe that zombies are real but physicalism is false. I just don't think anyone holds this position, so it's not clear who this argument is meant to convince. Some of these just amount to "if I can imagine it it's real" which is about as convincing as the "I can imagine it" argument for modal realism.
The notion that "if consciousness is purely physical, it would be possible to reconstruct experiences from knowledge" seems like an assertion without evidence. Suppose the experience of red was purely physical: when somebody sees red, an arrangement of 100 tungsten atoms appears in a neuron, now called the Red Neuron. Mary could know everything there is to know about how the Red Neuron works but as long as she doesn't have the Red Neuron, she hasn't seen red, because she doesn't have the tungsten atoms, and she can't will it into existence. If she were to artificially implant in herself 100 tungsten atoms to create a Red Neuron, she would remember seeing red and no longer be surprised upon seeing red for the "first" time despite never having seen it before. This obviously doesn't happen but it's not clear how the thought experiments involving qualia would disprove this account of events.
Incidentally, is there a particular change that inspired you to make your most recent post paid comments only? Too many morons in the comments? I fully respect everyone's right to limit the amount of mental pollution they encounter, just wondering since IIRC you often mention restrictions when you restrict posts.
Well a lot of people have been convinced by thinking about zombies. It's not that it would be possible to reconstruct experience without knowledge but that it would be possible to have all knowledge about consciousness without experiencing it, which is true if knowledge of the mental is just a kind of physical knowledge. Again, no one thinks she would actually see red, just that she'd know what red looks like.
Making most recent post only for paid commenters was an accident--I'll fix it. Though maybe I'll do it more because sometimes crazy comments are really annoying.
Wait - is the argument whether Mary ever actually "sees red", or whether she'd "learn something new about what it’s like to see red" by seeing red?
Physicalism might imply that it's possible to have all knowledge about seeing red without ever experiencing it, but it certainly doesn't imply that it's possible to gain that knowledge just by consuming an infinite number of textbooks. It could just be that there's no path leading purely through textbooks that brings her to the desirable end physical state. Or, if we imagine "ways of knowing" that are somehow supremely more powerful than textbooks, it no longer becomes "clearly impossible."
If you see 100 steel cubes lined up in a row, you may not learn anything new from seeing 101 steel cubes lined up in a row. You would not learn anything new upon seeing 101 cubes, nor would your curiosity about 101 cubes be satisfied in any way. Your previous experience with 100 cubes plus your mighty powers of extrapolation are entirely sufficient for you to know exactly what it is like to see 101 cubes. Perhaps Mary, if she were truly a being of vastly greater mental prowess than we were, could as easily extrapolate red from her existing experience + powers of reasoning as we can imagine 101 cubes.
The qualitativeness (1) and the absence of analysis (6) are challenges that should give a physicalist some doubt and humility. But they're not positive arguments for dualism or any alternative. They're just implications to think harder and to solve the hard problem.
Otherwise, this entire list just seems like different expressions and consequences of not personally thinking that consciousness is physical.
Eg. P-zombies obviously can't exist if consciousness is physical - they'd be conscious. Obviously it's *conceivable* to have a non-conscious zombie, but that's just saying that dualism itself is conceivable. I don't think many physicalists would deny that dualism is possible - they just don't think it's true.
I'm very willing to believe I'm just one of the people who's conceptually confused here, but it would be good to have it pinpointed.
"However, we can imagine a physical carbon copy of you that lacks consciousness. This shows consciousness is not purely physical, as we can’t imagine a carbon copy of H20 that isn’t water."
I strongly disagree with this mode of reasoning. Just because you can imagine it does not mean it can exist. Just because you can imagine a consciousness-less copy of yourself does not mean that consciousness is separate from the physical world; it just means that you don't understand it well enough.
I can imagine a carbon copy of a diesel engine that still works in a world where the autoignition point of diesel is 1000°C, but that does not mean that it would be possible in the real world — it just means that I don't understand diesel engines.
If I'm bad enough at physics, I *can* imagine a carbon copy of H20 that is not water.
There are a few basic arguments which just don't follow to me. Maybe you're relying on some intuition I don't share?
> Thus, the argument is as follows.
>
> 1 A being could be physically identical to me but could not be conscious.
>
> 2 Two beings that are physically identical must have all physical properties in common
>
> Therefore consciousness is not a physical property.
As far as I can tell all you can conclude from this argument is that consciousness is not _necessarily_ a physical property. But as long as we're talking about thought experiments in 1 surely this can't rule out consciousness as a physical property. After all, this is a purely logical argument, devoid of any facts about the world.
> If consciousness were a reductively explainable physical property then knowing all of the facts about the brain would make it possible to know what it's like to see red, despite being colour blind. However, this is clearly impossible.
It's not obvious to me that this is impossible. It may well be, but you don't prove it.
But, maybe more importantly, it's obvious to me that if consciousness were a reductively explainable physical property then knowing all the facts about the brain would make it possible to know whether that brain was conscious, or seeing red. But I don't see why it should necessarily give knowledge of what an experience feels like.
> disembodied heat is impossible
Yet I'm sure I can imagine disembodied heat. I know that's a paradox because I have a microscopic model of heat, but if I didn't it would feel very possible.
.....
It is seeming to me like some of this confusion might stem from using the word consciousness to mean two different things: the property of having internal subjective experiences, and the property of being able to make decisions.
It seems to me like lots of these arguments are much easier to accept in the latter (basically epiphenomenological, if that's the right word) case. Though even there I have an itch telling me something is missing from real understanding.
Basically at the end of the day I see a choice between postulating new fundamental laws and postulating the existence of a hard-to-derive consequence of existing laws. And it's very unclear to me which way Occam's razor should swing.
P.S.: Right at the end you claim
> Non physicalist theories are testable and make predictions
but the links here are to two different theories where consciousness is reduced to purely physical phenomena (electromagnetic fields are as physical as any particle, and quantum physics is still physics). This confused me.
//As far as I can tell all you can conclude from this argument is that consciousness is not _necessarily_ a physical property. But as long as we're talking about thought experiments in 1 surely this can't rule out consciousness as a physical property. After all, this is a purely logical argument, devoid of any facts about the world.//
Higher level physical properties supervene on lower level physical properties in the sense that any change in the higher level physical properties must be accompanied by changes in the lower level physical properties. You cannot eliminate a brick wall without hcanging the facts about any of the bricks. Note how you can have a physical replica of the world lacking consciousness but not one lacking chairs--because if it lacked chairs, it wouldn't be a physical replica. It would be missing the chairs.
//It's not obvious to me that this is impossible. It may well be, but you don't prove it.
But, maybe more importantly, it's obvious to me that if consciousness were a reductively explainable physical property then knowing all the facts about the brain would make it possible to know whether that brain was conscious, or seeing red. But I don't see why it should necessarily give knowledge of what an experience feels like.//
It is intuitively obvious--to me--that learning a bunch of neuroscience facts over a projector won't tell you what it's like to see red.
If all the facts about the brain are just higher-order facts about atoms, including what it's like to see red, then you could know them just by knowing various physical facts. For there to be facts that can't be communicated except by experience, they wouldn't be able to be explainable purely physically.
//It is seeming to me like some of this confusion might stem from using the word consciousness to mean two different things: the property of having internal subjective experiences, and the property of being able to make decisions.//
I am always using the term consciousness to mean the former. I disagree that it just comes down to Occam's razor on account of the arguments I give.
//but the links here are to two different theories where consciousness is reduced to purely physical phenomena (electromagnetic fields are as physical as any particle, and quantum physics is still physics). This confused me.//
Those theories are neutral with regards to ontology. Dualists agree that there are neural correlates of consciousness--brain regions that cause consciousness. We just think that's on account of more fundamental physical laws.
Well I have some strong sense that it’s wrong in many ways
First and foremost the claim that “all knowledge in the world cannot teach someone what’s it like to see red without explicitly seeing red” seems quite strange. People have quite complex features through which they perceive the world around them (e.g. eyes, ears, etc), so it’s fairly easy to accept from reductionalist perspective that if one hasn’t perceived a colour through seeing it, one cannot have an experience of “what it’s like to see red” if the key method to know that is through actually perceiving waves coming into one’s eyeballs and whole complex physical process that transfers information into neurons, etc
Consider the following example:
If you have some kind of AI, and you want it to know some features that are informationally orthogonal to (e.g. cannot be derived from) the train set of an AI, then it’s sort of obvious that you cannot expect an AI to extrapolate those features. If your brain is a machine that has some perceptors, and you are saying “well it’s impossible for this machine to have a state that requires explicit and specific features to be perceived yet without actually introducing those features to machine’s perceptors”, then for me it seems like begging the question.
I assume that experience of seeing red is causally explained by actually seeing waves of red spectrum going to perceptors in the eye, and causally cause some signals to be transferred through neurons to the brain, etc, etc.
So for me it seems at least plausible that one can stimulate the exact same neurons in the same way to make someone “know what it’s like to see red”
The idea is not that you would experience red when you've read some neuroscience even if you're color-blind. Instead, it's that you would know what it's like to see red even without seeing red if it's purely physical knowledge. Why would this be the only piece of physical knowledge that you can't gain without being in the state of the physical object? I can know all the facts about black holes without being a black hole.
I agree that certain brain states cause you to see red. But if physicalism were true, then we could know what mental states are like--e.g. seeing red--without experiencing them, because they're just ordinary physical knowledge.
I feel like this looks like you think that physicalism is some sort of reduction to knowledge where you confuse knowledge about one’s experience with directly having that experience, which is, what, obviously false, idk?
I guess there should be some more interesting way of thinking on behalf of physicalists
Well I guess I agree, but it seems like that’s not how smart people who claim to be physicalists think of their beliefs
I mean, clearly if you are a part of the experiencing process then you have to assume that some of your observations intrinsically depend on the way you perceive things and probably different ways of perceiving have different things they can perceive (doesn’t it sound like a tautology?)
So if you perceive something from reading a book, then using some thinking to come to a conclusion, it might be different from experiencing that through your eyes
I admire debunking weird views but I still don’t think that a reasonable physicalist would agree with premise 2 generalised (you prob wanted to say “all physical facts can be known without experiencing” which is imho clearly false”)
Then I might ask what the physicalism is in your opinion, since I think that physicalism is “I believe that all conscious experiences are the byproduct of biological/physical stuff going on inside brains”
That definition is ambiguous--there's a version that I'd agree with, and a version that I wouldn't. I think that brains cause consciousness because there are fundamental laws of nature that create consciousness that goes along with various brain states. So in one sense they're the byproduct of brains, even though brains are not--absent psychophysical laws--sufficient to get consciousness.
I would argue that every single argument in here that is based on my capabilities of imagination is invalid, since my imagination is completely irrelevant to the question at hand. Imagination is a concept that is derived from the inside, and therefore attempting to make arguments about the properties of the system itself by using one of its own tools subjected to its internal set of rules is circular reasoning.
"This shows consciousness is not purely physical, as we can’t imagine a carbon copy of H20 that isn’t water." - What the fuck, who are you to tell me what I can imagine? I'm sorry, I really wish I was able to find kinder words for this. First, we are comparing three atoms to the most complicated and most complex (for once it is correct to use both at the same time) mechanism of the known universe. Second, I can totally imagine a carbon copy of H2O that isn't water because my imagination is not subjected to phsyical limitations, which is a necessary condition derived from your assertion that consciousness, and therefore imagination, is not physical, which is exactly why I consider this circular reasoning. Third, that is a zero, not an O. As you can tell, I am steaming mad at this point.
"If consciousness were a reductively explainable physical property then knowing all of the facts about the brain would make it possible to know what it’s like to see red, despite being color blind. However, this is clearly impossible." - Why? Why? Whyyyyyyyyyyyy? What the fuck is even happening? What is clear about this? How arrogant can a conscious being possibly be to consider this statement obvious? I repeat, the brain is the most complicated and most complex mechanism of the known universe, and the tools that we have developed thanks to it have barely reached the point of fully simulating singular neurons. I'm sorry, but we know diddly squat about the brain.
"Knowing all the facts about the brain" is a state so far beyond anything imaginable (lol) that it is complete nonsense to use this hypothetical state to make any argument. I am getting flashbacks to Eliezer Yudkowsky's moral dilemma of "would you prefer that one person be horribly tortured for fifty years without hope or rest, or that 3^^^3 people get dust specks in their eyes?". Yes, your scope insensitivity is this bad, I genuinely believe this. 86 billion neurons is very very very far away from 3^^^3, but given the current state of affairs, it seems reasonable to me that the amount of resources it takes to model a system of 86 billion neurons in a way that makes it solvable from the outside is closer to 3^^^3 than it is to 1.
As an aside, because I am putting myself at risk of commiting a logical fallacy of at least equal egregiousness, even the assumption that "knowing all the facts about the brain" is a possibility at all seems bonkers to me, given what we know about math thanks to the incompleteness theorems. The existence of solutions to an equation (and therefore its accessibility from inside the system) does not require those equations to be computable and therefore accessible from the outside, in fact the vast majority of problems that are guaranteed to have solutions are also guaranteed to be unsolvable. If quintic equations are complex, I'm sorry, I mean complicated enough to give us headaches in this regard, how bad do you think 86 billion neurons are going to be?
I am glad that you wrote this piece and I enjoyed becoming furiously angry with it though because I thoroughly enjoy this subject. So, thank you very much.
Hi Ben, thanks for the comment. One brief note: You seem very indignant about this post. Here, I say things that are bog standard in philosophy of mind, so if you find it crazy, that should serve as some evidence that this is confusion on your part not mine.
When we talk about conceivability, we're talking about whether something could be ruled out a priori. You can't have a physical copy of a table lacking legs, because legs are a physical property. You can, however, have a physical copy of a person lacking consciousness.
As for the water being H20 example, once we know all the facts about H20, we realize that you can have something that fills the role of water, but it wouldn't be water absent H20. But there's no explanation like that in the case of consciousness--we can imagine behaviorally identical things lacking consciousness.
When I say know all the facts about the brain, I'm referring to the behavior of all the neurons, which can be predicted if physicalism is true.
If I had to boil down my resume to one word, confusion is probably what would remain, so no disagreement so far.
"The role of water" is a concept inside of consciousness, as is the concept of concepts, which is why I remain convinced that all of this is circular reasoning.
The difference between the most complex state that can be solved with our current capabilities and the most complex state that has guaranteed solutions while still being expressible within the boundaries of physicalism is so enormous that I can't help but laugh at the idea that there could be a rigorous way to argue that consciousness must strictly fall outside of physicalism with reasonable probability. Right now, you are demonstrating that consciousness of most people is incapable of properly assessing the scope of physicality (including me, I'm just a clown with numbers too but at least I have noticed my red nose). And what remains when you take 1 minus that probability, is the probability for all of this being a product of egocentrism, which would at least be consistent with inside reasoning mistaking itself for outside reasoning.
However, if you put me on the spot and asked me "okay genius, what is consciousness then?", my answer would be "go back to bed", so I may just be notoriously not fun to talk to.
I think we are orders of magnitude closer to rigorously proving that it is impossible to answer meaningful questions about consciousness from inside consciousness, than we are to actually answering those questions, and we are not very close to either of those. And the reason for my believe is once again Kurt Gödel. If we know one thing about the universe, it is that it very well knows what "fuck you" means.
I was using the role of water in a technical sense meaning whatever, in the actual world, is responsible for the watery properties. We know now that water is H20, but if we had discovered that the clear watery substance that fills lakes and rivers was XYZ, then that would have been water instead. So I think that there might be cases where you think you can conceive of a world without some substance, when really the connection between the substance and the object is necessary. But the point is that though you can seem to imagine a world physically identical to ours without water before we knew that water was H20, we couldn't imagine a physically identical world lacking watery substances, which are whatever substances fulfill the functional role of water. You can, however, imagine a world lacking consciousnessy substances that is physically identical.
Consciousness is unique--there are no other properties whose absence seems to be conceivable.
Maybe it warrants an explanation on why I am so hung up on math and mathmatical language even though we are talking about conciousness.
So, math is not the real world. Even though we would consider the square root of 2 to be a real number, it is not real in any meaningful way, it is a monstrosity that arose from inside our concsious heads. But it is irrelevant what math is, because math is all we have. Math is the attempt of formalizing information conceivable to conscious individuals in such a rigorious way, that makes it theoretically and practically transferable with 100% accuracy and 0% loss. There is a lower bound on competence for sender and receiver, but if this bound is met, then 100% accuracy is achievable.
And so far, it is the only "thing" that has ever achieved this for us, because bog-standard language is precisely not this. It is not accurate and it's not lossless - this isn't a bad thing, language is very very useful, it just is what it is. Math is the one tool that allows us to take little pieces that arose from our trapped insides and transfer it to other trapped insides via the outside world, with the help of physical phenomenons like oscillating air pressure or electronic circuitry, and have verifiable rates of success.
Now, math is also very very weird. I have mentioned the square root of 2 before. I could jump right ahead towards behemoths like the incompleteness theorems, but even ideas like the Riemann-Zeta-Function are simple enough that a high-schooler could understand how you compute it for inputs between 0 and 1, yet the complications that arise from it have escaped the total computing power of all our conscious minds so far.
And all of this weirdness strictly arose from the condition of rigor. That's all it is. An internal logic that can be verifiably 100% transfered to others. Rigor is required to do that, but at the same time, it is enough to make the system explode into its own universe of horrifying monsters, full of infinitely deep holes and dark abysses. If physics is simply the attempt to extend this standard of formalization and strictly point it towards everything that is outside of our consciousness (like, the universe for example), then the upper bound on expected weirdness that arose from the necessary condition of rigor and therefore preserves the rigor of the system is so enormously high, that no philosophical argument is ever going to convince me, that of all things, consciousness has to be above this bound.
The universe is very very very weird. What sets consciousness apart, what makes it "unique" as you say, is not related to its properties or degree of weirdness at all. What sets it apart is that it is the one system that we are inside of. That's it. And while I know barely anything about the bounding properties of that system, I know enough about its inner workings that it definitely has a non-zero amount of bias when it comes to seeing itself as unique, and since the overall confidence levels of any reasonable alternative explanation are so abysmally low, this non-zero bias is almost always enough to overpower them. That doesn't mean that we have moved towards a more plausible explanation, quite the oppsite. We are just confusing expected noise for signal because we felt the need to turn the amplifier to 11.
We can imagine a world without consciousnessy substances that is physically identical because we know nothing about either worlds. I still don't understand why our imagination is relevant here. The solution to the equation posed by what is water is formed by three atoms, 2 Hs and an O, so if we can't "imagine" a world where water isn't H2O, then this has nothing to do with imagination at all, but just the fact that this is a solvable equation from inside and outside the system posed by "water". The solution to that equation is three atoms. There is no transferable knowledge arising from this observation at all. Maybe towards other three-atom-problems, but certainly not about consciousness. I have no problem accepting the notion that a physically identically world to ours without consciousness may be ludicrous, simply because I know so little about it. Whatever probability I assign to either case, my confidence rounds down to zero.
I'm enjoying this exchange and I'm glad that Ben is bringing Godel and mathematical logic to the discussion. Nagel really follows Godel's anti-reductionist approach, so Ben's discussion of inside vs. outside of reason, rationality, and logic are very appropriate here. Of course, Godel was really a Platonist and believed that some truths are beyond the limits of math and logic. But Godel is really talking about the contradiction and paradox at the center of any finite logical system, so it's different than saying consciousness is non-physical.
Premise 1 has not been established. Chalmers says that the reason we have to accept it comes down to intuition (presumably because it is quite difficult to "prove") but I don't immediately share the intuition, and neither do many philosophers.
Have you debated James Fodor? If I'm not mistaken he is a physicalist who prefers functionalist explanations. It's plausible to me that in your water = H2O example, we experience some properties of water like wetness and what water "feels like" but we aren't conscious of the particles that constitute water - and similarly, our inability to give a reductionist explanation because we only experience mental states and have extremely limited knowledge of how the brain works could not be the basis for an inference that reductionist accounts don't work
Well, there would have to be some account of why it's impossible. Additionally, the possibility of zombies seems hard to deny, when properly understood. Physics explains what matter does, but you could imagine it having different internal experiences, while doing the same things. I have debated Fodor, but I was a materialist back then. I'm not sure what you're saying about the water H20 case.
Wait what - that's just not true *at all*. To the point where I somehow doubt that you have actually read Chalmers' paper about the zombie argument. Chalmers argues for P1 at length, in fact he spends numerous pages on arguing for the idea that 1) P-zombies are ideally conceivable and 2) that ideal conceivability entails possibility... to say that he mainly appeals to intuition seems like a mischaracterisation of his actual work.
Most philosophers, even physicalists, accept 1) btw. The disagreement is essentially about 2), where we have incredibly sophisticated arguments on both sides
Hey that’s not what I said. Chalmers does make arguments why we should in fact accept premise 1, but the fact that he made arguments is not in dispute. I said that there are other people who disagree with these arguments, which leads me to believe it has not been established. Also, he argues that it is a concept that should be intuitive and can be made intuitive, but ultimately it is difficult to “prove.” I didn’t say he “mainly appeals to intuition.”
I mean I obviously agree that it's not established - but the same could be said about basically everything in philosophy, not even modus ponens or the law of non-contradiction are established anymore.
You definitely made it sound as if he primarily relies on vague intuition - if this is not what you actually believe, then fair enough :)
Wow, we actually agree for once! Panpsychism is so much more plausible than reductive physicalism.
A lot of these arguments don't seem very good. Some of them seem to be arguments based off things that people already agree with you on. Obviously, if zombies are real, then physicalism is false. I guess this would convince people who believe that zombies are real but physicalism is false. I just don't think anyone holds this position, so it's not clear who this argument is meant to convince. Some of these just amount to "if I can imagine it it's real" which is about as convincing as the "I can imagine it" argument for modal realism.
The notion that "if consciousness is purely physical, it would be possible to reconstruct experiences from knowledge" seems like an assertion without evidence. Suppose the experience of red was purely physical: when somebody sees red, an arrangement of 100 tungsten atoms appears in a neuron, now called the Red Neuron. Mary could know everything there is to know about how the Red Neuron works but as long as she doesn't have the Red Neuron, she hasn't seen red, because she doesn't have the tungsten atoms, and she can't will it into existence. If she were to artificially implant in herself 100 tungsten atoms to create a Red Neuron, she would remember seeing red and no longer be surprised upon seeing red for the "first" time despite never having seen it before. This obviously doesn't happen but it's not clear how the thought experiments involving qualia would disprove this account of events.
Incidentally, is there a particular change that inspired you to make your most recent post paid comments only? Too many morons in the comments? I fully respect everyone's right to limit the amount of mental pollution they encounter, just wondering since IIRC you often mention restrictions when you restrict posts.
Well a lot of people have been convinced by thinking about zombies. It's not that it would be possible to reconstruct experience without knowledge but that it would be possible to have all knowledge about consciousness without experiencing it, which is true if knowledge of the mental is just a kind of physical knowledge. Again, no one thinks she would actually see red, just that she'd know what red looks like.
Making most recent post only for paid commenters was an accident--I'll fix it. Though maybe I'll do it more because sometimes crazy comments are really annoying.
Wait - is the argument whether Mary ever actually "sees red", or whether she'd "learn something new about what it’s like to see red" by seeing red?
Physicalism might imply that it's possible to have all knowledge about seeing red without ever experiencing it, but it certainly doesn't imply that it's possible to gain that knowledge just by consuming an infinite number of textbooks. It could just be that there's no path leading purely through textbooks that brings her to the desirable end physical state. Or, if we imagine "ways of knowing" that are somehow supremely more powerful than textbooks, it no longer becomes "clearly impossible."
If you see 100 steel cubes lined up in a row, you may not learn anything new from seeing 101 steel cubes lined up in a row. You would not learn anything new upon seeing 101 cubes, nor would your curiosity about 101 cubes be satisfied in any way. Your previous experience with 100 cubes plus your mighty powers of extrapolation are entirely sufficient for you to know exactly what it is like to see 101 cubes. Perhaps Mary, if she were truly a being of vastly greater mental prowess than we were, could as easily extrapolate red from her existing experience + powers of reasoning as we can imagine 101 cubes.
The qualitativeness (1) and the absence of analysis (6) are challenges that should give a physicalist some doubt and humility. But they're not positive arguments for dualism or any alternative. They're just implications to think harder and to solve the hard problem.
Otherwise, this entire list just seems like different expressions and consequences of not personally thinking that consciousness is physical.
Eg. P-zombies obviously can't exist if consciousness is physical - they'd be conscious. Obviously it's *conceivable* to have a non-conscious zombie, but that's just saying that dualism itself is conceivable. I don't think many physicalists would deny that dualism is possible - they just don't think it's true.
I'm very willing to believe I'm just one of the people who's conceptually confused here, but it would be good to have it pinpointed.
"However, we can imagine a physical carbon copy of you that lacks consciousness. This shows consciousness is not purely physical, as we can’t imagine a carbon copy of H20 that isn’t water."
I strongly disagree with this mode of reasoning. Just because you can imagine it does not mean it can exist. Just because you can imagine a consciousness-less copy of yourself does not mean that consciousness is separate from the physical world; it just means that you don't understand it well enough.
I can imagine a carbon copy of a diesel engine that still works in a world where the autoignition point of diesel is 1000°C, but that does not mean that it would be possible in the real world — it just means that I don't understand diesel engines.
If I'm bad enough at physics, I *can* imagine a carbon copy of H20 that is not water.
There are a few basic arguments which just don't follow to me. Maybe you're relying on some intuition I don't share?
> Thus, the argument is as follows.
>
> 1 A being could be physically identical to me but could not be conscious.
>
> 2 Two beings that are physically identical must have all physical properties in common
>
> Therefore consciousness is not a physical property.
As far as I can tell all you can conclude from this argument is that consciousness is not _necessarily_ a physical property. But as long as we're talking about thought experiments in 1 surely this can't rule out consciousness as a physical property. After all, this is a purely logical argument, devoid of any facts about the world.
> If consciousness were a reductively explainable physical property then knowing all of the facts about the brain would make it possible to know what it's like to see red, despite being colour blind. However, this is clearly impossible.
It's not obvious to me that this is impossible. It may well be, but you don't prove it.
But, maybe more importantly, it's obvious to me that if consciousness were a reductively explainable physical property then knowing all the facts about the brain would make it possible to know whether that brain was conscious, or seeing red. But I don't see why it should necessarily give knowledge of what an experience feels like.
> disembodied heat is impossible
Yet I'm sure I can imagine disembodied heat. I know that's a paradox because I have a microscopic model of heat, but if I didn't it would feel very possible.
.....
It is seeming to me like some of this confusion might stem from using the word consciousness to mean two different things: the property of having internal subjective experiences, and the property of being able to make decisions.
It seems to me like lots of these arguments are much easier to accept in the latter (basically epiphenomenological, if that's the right word) case. Though even there I have an itch telling me something is missing from real understanding.
Basically at the end of the day I see a choice between postulating new fundamental laws and postulating the existence of a hard-to-derive consequence of existing laws. And it's very unclear to me which way Occam's razor should swing.
P.S.: Right at the end you claim
> Non physicalist theories are testable and make predictions
but the links here are to two different theories where consciousness is reduced to purely physical phenomena (electromagnetic fields are as physical as any particle, and quantum physics is still physics). This confused me.
//As far as I can tell all you can conclude from this argument is that consciousness is not _necessarily_ a physical property. But as long as we're talking about thought experiments in 1 surely this can't rule out consciousness as a physical property. After all, this is a purely logical argument, devoid of any facts about the world.//
Higher level physical properties supervene on lower level physical properties in the sense that any change in the higher level physical properties must be accompanied by changes in the lower level physical properties. You cannot eliminate a brick wall without hcanging the facts about any of the bricks. Note how you can have a physical replica of the world lacking consciousness but not one lacking chairs--because if it lacked chairs, it wouldn't be a physical replica. It would be missing the chairs.
//It's not obvious to me that this is impossible. It may well be, but you don't prove it.
But, maybe more importantly, it's obvious to me that if consciousness were a reductively explainable physical property then knowing all the facts about the brain would make it possible to know whether that brain was conscious, or seeing red. But I don't see why it should necessarily give knowledge of what an experience feels like.//
It is intuitively obvious--to me--that learning a bunch of neuroscience facts over a projector won't tell you what it's like to see red.
If all the facts about the brain are just higher-order facts about atoms, including what it's like to see red, then you could know them just by knowing various physical facts. For there to be facts that can't be communicated except by experience, they wouldn't be able to be explainable purely physically.
//It is seeming to me like some of this confusion might stem from using the word consciousness to mean two different things: the property of having internal subjective experiences, and the property of being able to make decisions.//
I am always using the term consciousness to mean the former. I disagree that it just comes down to Occam's razor on account of the arguments I give.
//but the links here are to two different theories where consciousness is reduced to purely physical phenomena (electromagnetic fields are as physical as any particle, and quantum physics is still physics). This confused me.//
Those theories are neutral with regards to ontology. Dualists agree that there are neural correlates of consciousness--brain regions that cause consciousness. We just think that's on account of more fundamental physical laws.
Well I have some strong sense that it’s wrong in many ways
First and foremost the claim that “all knowledge in the world cannot teach someone what’s it like to see red without explicitly seeing red” seems quite strange. People have quite complex features through which they perceive the world around them (e.g. eyes, ears, etc), so it’s fairly easy to accept from reductionalist perspective that if one hasn’t perceived a colour through seeing it, one cannot have an experience of “what it’s like to see red” if the key method to know that is through actually perceiving waves coming into one’s eyeballs and whole complex physical process that transfers information into neurons, etc
Consider the following example:
If you have some kind of AI, and you want it to know some features that are informationally orthogonal to (e.g. cannot be derived from) the train set of an AI, then it’s sort of obvious that you cannot expect an AI to extrapolate those features. If your brain is a machine that has some perceptors, and you are saying “well it’s impossible for this machine to have a state that requires explicit and specific features to be perceived yet without actually introducing those features to machine’s perceptors”, then for me it seems like begging the question.
I assume that experience of seeing red is causally explained by actually seeing waves of red spectrum going to perceptors in the eye, and causally cause some signals to be transferred through neurons to the brain, etc, etc.
So for me it seems at least plausible that one can stimulate the exact same neurons in the same way to make someone “know what it’s like to see red”
Correct me if I’m wrong, please.
The idea is not that you would experience red when you've read some neuroscience even if you're color-blind. Instead, it's that you would know what it's like to see red even without seeing red if it's purely physical knowledge. Why would this be the only piece of physical knowledge that you can't gain without being in the state of the physical object? I can know all the facts about black holes without being a black hole.
Well, I guess you could theoretically trigger some neurons in your eyes to make you feel like you see red
Or even make you genuinely see red
Doesn’t it contradict the original claim?
Also, black holes aren’t the part of your brain, so this seems quite strange, sort of like confusing knowledge about something with that something
I agree that certain brain states cause you to see red. But if physicalism were true, then we could know what mental states are like--e.g. seeing red--without experiencing them, because they're just ordinary physical knowledge.
I feel like this looks like you think that physicalism is some sort of reduction to knowledge where you confuse knowledge about one’s experience with directly having that experience, which is, what, obviously false, idk?
I guess there should be some more interesting way of thinking on behalf of physicalists
No! No part of the argument assumes that having an experience is the same as having knowledge of the experience. The argument is
1) If physicalism is true, then consciousness is purely physical.
2) You can know physical facts without experiencing them just by reading them in a textbook, for example.
3) Therefore, if physicalism is true, then you can know all the physical facts without experiencing them.
4) You can't know the physical facts without experiencing them.
5) So physicalism is false.
Shit my last comment was written weirdly
Anyway, I guess that premise 2 doesn’t cause premise 3 in this way
Ability to know some physical facts without experiencing them doesn’t mean that you can know all the physical facts without experiencing them
Well I guess I agree, but it seems like that’s not how smart people who claim to be physicalists think of their beliefs
I mean, clearly if you are a part of the experiencing process then you have to assume that some of your observations intrinsically depend on the way you perceive things and probably different ways of perceiving have different things they can perceive (doesn’t it sound like a tautology?)
So if you perceive something from reading a book, then using some thinking to come to a conclusion, it might be different from experiencing that through your eyes
I admire debunking weird views but I still don’t think that a reasonable physicalist would agree with premise 2 generalised (you prob wanted to say “all physical facts can be known without experiencing” which is imho clearly false”)
Then I might ask what the physicalism is in your opinion, since I think that physicalism is “I believe that all conscious experiences are the byproduct of biological/physical stuff going on inside brains”
That definition is ambiguous--there's a version that I'd agree with, and a version that I wouldn't. I think that brains cause consciousness because there are fundamental laws of nature that create consciousness that goes along with various brain states. So in one sense they're the byproduct of brains, even though brains are not--absent psychophysical laws--sufficient to get consciousness.
I would argue that every single argument in here that is based on my capabilities of imagination is invalid, since my imagination is completely irrelevant to the question at hand. Imagination is a concept that is derived from the inside, and therefore attempting to make arguments about the properties of the system itself by using one of its own tools subjected to its internal set of rules is circular reasoning.
"This shows consciousness is not purely physical, as we can’t imagine a carbon copy of H20 that isn’t water." - What the fuck, who are you to tell me what I can imagine? I'm sorry, I really wish I was able to find kinder words for this. First, we are comparing three atoms to the most complicated and most complex (for once it is correct to use both at the same time) mechanism of the known universe. Second, I can totally imagine a carbon copy of H2O that isn't water because my imagination is not subjected to phsyical limitations, which is a necessary condition derived from your assertion that consciousness, and therefore imagination, is not physical, which is exactly why I consider this circular reasoning. Third, that is a zero, not an O. As you can tell, I am steaming mad at this point.
"If consciousness were a reductively explainable physical property then knowing all of the facts about the brain would make it possible to know what it’s like to see red, despite being color blind. However, this is clearly impossible." - Why? Why? Whyyyyyyyyyyyy? What the fuck is even happening? What is clear about this? How arrogant can a conscious being possibly be to consider this statement obvious? I repeat, the brain is the most complicated and most complex mechanism of the known universe, and the tools that we have developed thanks to it have barely reached the point of fully simulating singular neurons. I'm sorry, but we know diddly squat about the brain.
"Knowing all the facts about the brain" is a state so far beyond anything imaginable (lol) that it is complete nonsense to use this hypothetical state to make any argument. I am getting flashbacks to Eliezer Yudkowsky's moral dilemma of "would you prefer that one person be horribly tortured for fifty years without hope or rest, or that 3^^^3 people get dust specks in their eyes?". Yes, your scope insensitivity is this bad, I genuinely believe this. 86 billion neurons is very very very far away from 3^^^3, but given the current state of affairs, it seems reasonable to me that the amount of resources it takes to model a system of 86 billion neurons in a way that makes it solvable from the outside is closer to 3^^^3 than it is to 1.
As an aside, because I am putting myself at risk of commiting a logical fallacy of at least equal egregiousness, even the assumption that "knowing all the facts about the brain" is a possibility at all seems bonkers to me, given what we know about math thanks to the incompleteness theorems. The existence of solutions to an equation (and therefore its accessibility from inside the system) does not require those equations to be computable and therefore accessible from the outside, in fact the vast majority of problems that are guaranteed to have solutions are also guaranteed to be unsolvable. If quintic equations are complex, I'm sorry, I mean complicated enough to give us headaches in this regard, how bad do you think 86 billion neurons are going to be?
I am glad that you wrote this piece and I enjoyed becoming furiously angry with it though because I thoroughly enjoy this subject. So, thank you very much.
Hi Ben, thanks for the comment. One brief note: You seem very indignant about this post. Here, I say things that are bog standard in philosophy of mind, so if you find it crazy, that should serve as some evidence that this is confusion on your part not mine.
When we talk about conceivability, we're talking about whether something could be ruled out a priori. You can't have a physical copy of a table lacking legs, because legs are a physical property. You can, however, have a physical copy of a person lacking consciousness.
As for the water being H20 example, once we know all the facts about H20, we realize that you can have something that fills the role of water, but it wouldn't be water absent H20. But there's no explanation like that in the case of consciousness--we can imagine behaviorally identical things lacking consciousness.
When I say know all the facts about the brain, I'm referring to the behavior of all the neurons, which can be predicted if physicalism is true.
If I had to boil down my resume to one word, confusion is probably what would remain, so no disagreement so far.
"The role of water" is a concept inside of consciousness, as is the concept of concepts, which is why I remain convinced that all of this is circular reasoning.
The difference between the most complex state that can be solved with our current capabilities and the most complex state that has guaranteed solutions while still being expressible within the boundaries of physicalism is so enormous that I can't help but laugh at the idea that there could be a rigorous way to argue that consciousness must strictly fall outside of physicalism with reasonable probability. Right now, you are demonstrating that consciousness of most people is incapable of properly assessing the scope of physicality (including me, I'm just a clown with numbers too but at least I have noticed my red nose). And what remains when you take 1 minus that probability, is the probability for all of this being a product of egocentrism, which would at least be consistent with inside reasoning mistaking itself for outside reasoning.
However, if you put me on the spot and asked me "okay genius, what is consciousness then?", my answer would be "go back to bed", so I may just be notoriously not fun to talk to.
I think we are orders of magnitude closer to rigorously proving that it is impossible to answer meaningful questions about consciousness from inside consciousness, than we are to actually answering those questions, and we are not very close to either of those. And the reason for my believe is once again Kurt Gödel. If we know one thing about the universe, it is that it very well knows what "fuck you" means.
I was using the role of water in a technical sense meaning whatever, in the actual world, is responsible for the watery properties. We know now that water is H20, but if we had discovered that the clear watery substance that fills lakes and rivers was XYZ, then that would have been water instead. So I think that there might be cases where you think you can conceive of a world without some substance, when really the connection between the substance and the object is necessary. But the point is that though you can seem to imagine a world physically identical to ours without water before we knew that water was H20, we couldn't imagine a physically identical world lacking watery substances, which are whatever substances fulfill the functional role of water. You can, however, imagine a world lacking consciousnessy substances that is physically identical.
Consciousness is unique--there are no other properties whose absence seems to be conceivable.
Maybe it warrants an explanation on why I am so hung up on math and mathmatical language even though we are talking about conciousness.
So, math is not the real world. Even though we would consider the square root of 2 to be a real number, it is not real in any meaningful way, it is a monstrosity that arose from inside our concsious heads. But it is irrelevant what math is, because math is all we have. Math is the attempt of formalizing information conceivable to conscious individuals in such a rigorious way, that makes it theoretically and practically transferable with 100% accuracy and 0% loss. There is a lower bound on competence for sender and receiver, but if this bound is met, then 100% accuracy is achievable.
And so far, it is the only "thing" that has ever achieved this for us, because bog-standard language is precisely not this. It is not accurate and it's not lossless - this isn't a bad thing, language is very very useful, it just is what it is. Math is the one tool that allows us to take little pieces that arose from our trapped insides and transfer it to other trapped insides via the outside world, with the help of physical phenomenons like oscillating air pressure or electronic circuitry, and have verifiable rates of success.
Now, math is also very very weird. I have mentioned the square root of 2 before. I could jump right ahead towards behemoths like the incompleteness theorems, but even ideas like the Riemann-Zeta-Function are simple enough that a high-schooler could understand how you compute it for inputs between 0 and 1, yet the complications that arise from it have escaped the total computing power of all our conscious minds so far.
And all of this weirdness strictly arose from the condition of rigor. That's all it is. An internal logic that can be verifiably 100% transfered to others. Rigor is required to do that, but at the same time, it is enough to make the system explode into its own universe of horrifying monsters, full of infinitely deep holes and dark abysses. If physics is simply the attempt to extend this standard of formalization and strictly point it towards everything that is outside of our consciousness (like, the universe for example), then the upper bound on expected weirdness that arose from the necessary condition of rigor and therefore preserves the rigor of the system is so enormously high, that no philosophical argument is ever going to convince me, that of all things, consciousness has to be above this bound.
The universe is very very very weird. What sets consciousness apart, what makes it "unique" as you say, is not related to its properties or degree of weirdness at all. What sets it apart is that it is the one system that we are inside of. That's it. And while I know barely anything about the bounding properties of that system, I know enough about its inner workings that it definitely has a non-zero amount of bias when it comes to seeing itself as unique, and since the overall confidence levels of any reasonable alternative explanation are so abysmally low, this non-zero bias is almost always enough to overpower them. That doesn't mean that we have moved towards a more plausible explanation, quite the oppsite. We are just confusing expected noise for signal because we felt the need to turn the amplifier to 11.
We can imagine a world without consciousnessy substances that is physically identical because we know nothing about either worlds. I still don't understand why our imagination is relevant here. The solution to the equation posed by what is water is formed by three atoms, 2 Hs and an O, so if we can't "imagine" a world where water isn't H2O, then this has nothing to do with imagination at all, but just the fact that this is a solvable equation from inside and outside the system posed by "water". The solution to that equation is three atoms. There is no transferable knowledge arising from this observation at all. Maybe towards other three-atom-problems, but certainly not about consciousness. I have no problem accepting the notion that a physically identically world to ours without consciousness may be ludicrous, simply because I know so little about it. Whatever probability I assign to either case, my confidence rounds down to zero.
I'm enjoying this exchange and I'm glad that Ben is bringing Godel and mathematical logic to the discussion. Nagel really follows Godel's anti-reductionist approach, so Ben's discussion of inside vs. outside of reason, rationality, and logic are very appropriate here. Of course, Godel was really a Platonist and believed that some truths are beyond the limits of math and logic. But Godel is really talking about the contradiction and paradox at the center of any finite logical system, so it's different than saying consciousness is non-physical.
Premise 1 has not been established. Chalmers says that the reason we have to accept it comes down to intuition (presumably because it is quite difficult to "prove") but I don't immediately share the intuition, and neither do many philosophers.
Have you debated James Fodor? If I'm not mistaken he is a physicalist who prefers functionalist explanations. It's plausible to me that in your water = H2O example, we experience some properties of water like wetness and what water "feels like" but we aren't conscious of the particles that constitute water - and similarly, our inability to give a reductionist explanation because we only experience mental states and have extremely limited knowledge of how the brain works could not be the basis for an inference that reductionist accounts don't work
Well, there would have to be some account of why it's impossible. Additionally, the possibility of zombies seems hard to deny, when properly understood. Physics explains what matter does, but you could imagine it having different internal experiences, while doing the same things. I have debated Fodor, but I was a materialist back then. I'm not sure what you're saying about the water H20 case.
Wait what - that's just not true *at all*. To the point where I somehow doubt that you have actually read Chalmers' paper about the zombie argument. Chalmers argues for P1 at length, in fact he spends numerous pages on arguing for the idea that 1) P-zombies are ideally conceivable and 2) that ideal conceivability entails possibility... to say that he mainly appeals to intuition seems like a mischaracterisation of his actual work.
Most philosophers, even physicalists, accept 1) btw. The disagreement is essentially about 2), where we have incredibly sophisticated arguments on both sides
Hey that’s not what I said. Chalmers does make arguments why we should in fact accept premise 1, but the fact that he made arguments is not in dispute. I said that there are other people who disagree with these arguments, which leads me to believe it has not been established. Also, he argues that it is a concept that should be intuitive and can be made intuitive, but ultimately it is difficult to “prove.” I didn’t say he “mainly appeals to intuition.”
I mean I obviously agree that it's not established - but the same could be said about basically everything in philosophy, not even modus ponens or the law of non-contradiction are established anymore.
You definitely made it sound as if he primarily relies on vague intuition - if this is not what you actually believe, then fair enough :)
Yes - definitely not my intention. I understand that my commentary is potentially misleading
That's fair, have a nice day! :)