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It's not obvious at all. The following isn't a proof and if I had one I'd be publishing elsewhere. However, I believe it suffices to show the lack of obviousnes

by User23 5y ago

It's not obvious at all. The following isn't a proof and if I had one I'd be publishing elsewhere. However, I believe it suffices to show the lack of obviousness. All of our models of reality are restricted to computable functions. However, we know that uncomputable functions not only exist, but that nearly all functions are in fact uncomputable. Therefore, it's well within the realm of plausibility that the actual behavior of the universe is governed by uncomputable functions, and we are forever stuck modeling those behaviors with computable approximations. To claim that reality is entirely computable, one has to show how uncomputable functions can exist therein. I wouldn't call this proof, but it strongly suggests to me that the behavior of the system we call reality is uncomputable, and that subsystems thereof also may not be. If what we call human intelligence is one of those uncomputable subsystems, then it's true that computational AI will never achieve it. Nonetheless, we've gotten pretty far with computable approximations, so machine "intelligence" that's close enough for practical purposes doesn't strike me as impossible even if we inhabit an uncomputable reality.

naasking 5y ago
> Therefore, it's well within the realm of plausibility that the actual behavior of the universe is governed by uncomputable functions, and we are forever stuck modeling those behaviors with computable approximations. Even if the set of uncomputable functions outnumbers the set of of computable functions, I still don't see how your conclusion follows. The rules that govern a coherent universe are not randomly sampled from the set of all functions.
Tzt 5y ago
why not make AI on the same platform as the human brain? what is so exceptional about it, and even if it is an exceptional material, why not just use it?
simonh 5y ago
I don’t see why we have to compute all of reality to create an AI anyway. I’m intelligent, to a point, and I’m pretty sure I don’t compute all reality. My neurological processes simply model enough of reality for me to function more or less effectively, that’s all. The article works from the absurd premise that an AI would have to perfectly model its environment, but no living creatures do this. It also decides that we can’t create general AI because we don’t know how to do it. Therefore it’s impossible. Seriously, it’s right there in the conclusion.
- checkyoursudo 5y ago
  ^ This is really the point. Human intelligence is based on limited and filtered input, rough analog approximations in processing, and incomplete and interpolated mental representations and internal simulations, and yet nobody seriously denies that we possess some degree of intelligence. I am skeptical that current methods will get us to AGI, but the idea that machines must achieve some level of computational perfection far above and beyond humans is not reasonable.
- ffwd 5y ago
  One thing I think is interesting about the paper is how complex systems (like the brain) change over _time_ rather than at fixed points, and if those changes are computable in any meaningful way. Like if we created an AI 100 years ago, could the AI 100 years later learn how to use an ipad or understand what twitter is or what a meme is? What if brain changes from cultural (environmental) change are both complex and thus creating mathematical models that would change the intelligence of the AI in the way the brain changes is impossible. Like physical changes in the circuits in the brain that are so distributed, interconnected and complicated and subtle yet very specifically "tailored" to the complex system so as to make them virtually impossible to abstract or model in any way, and thus changes the "mathematical model" of the brain that is sort of "virtualized" at a fixed point in time. Edit: Well to put it a little more explicitly: What if the real reason brains are intelligent is not because of the brain alone, but also because of the underlying physical systems like molecules, maybe even going all the way down to quantum mechanics and that those lower levels cause changes over time that fundamentally alters the function of the brain but still has the evolutionary potential of the lower level physical stuff. If you have 2 levels: 1) the brain 2) the underlying physical stuff below neurons 1 is a virtualized fixed point in time that we can model and 2 is part of a complex system that alters 1 but importantly in a way that cannot be computed without simulating that stuff at the lower level. I feel like this is sort of implied in the article because either intelligence can be abstracted completely accurately or there will (as the paper claims) always be lower level physical changes that alters the intelligence in a way that cannot be computed at the brain/intelligence level. I don't know if this is true though tbh
mcguire 5y ago
"Therefore, it's well within the realm of plausibility that the actual behavior of the universe is governed by uncomputable functions..." It's also well within the realm of plausibility that the behavior of the universe is governed by invisible, intangible unicorns. :-) If you can provide an example of something in the universe actually computing an theoretically uncomputable function, then there is a gigantic problem somewhere and everyone is going to have to do some re-thinking. If.
- User23 5y ago
  By definition nothing will ever compute an uncomputable function. You’re only stating a trivial truth that by itself fails to refute the conjecture that we live in a reality that has behaviors that cannot be accurately described by computable functions and that we are forever stuck with merely approximate computable models. In fact, so far we’re not able to completely computationally predict any behavior of reality. Even the marvelous theory of quantum electrodynamics is only shown to be accurate to, last I knew, about a dozen places. Due to an unfortunately widespread misunderstanding of the Church-Turing thesis, far too many otherwise intelligent persons with some CS knowledge are completely blinkered to the possibility that the universe could have behaviors that are real, but not describable with computable functions beyond approximately. The practicing laboratory scientists I’ve spoken with don’t generally share that defect since they’re used to everything being approximate.
  - mannykannot 5y ago
    I think you have a valid point here, but it does not do anything to save this paper. The paper claims to have refuted the possibility of what Searle calls Strong AI, but speculating that the universe has behaviors not describable with computable functions does not justify that conclusion. As Simonh pointed out above [1], Strong AI does not imply or depend on everything about the universe being computable, and even if it did, mere speculation that some unknown thing about the universe might not be computable would not justify inferring that therefore Strong AI must be impossible. This paper is combination of an unargued-for tacit premise with a rather blatant case of burden shifting. [1] https://news.ycombinator.com/item?id=29291286 https://news.ycombinator.com/item?id=29291286
ericjang 5y ago
Whether certain behaviors in the universe are uncomputable or not is irrelevant. If we classify "humans" as intelligent and assume no spooky immaterial aspects of consciousness, you already have an existence proof that intelligence is computable.
- User23 5y ago
  That doesn't follow from the given premises. I assume the hidden leg of your rhetorical enthymeme is that the universe is a Turing machine. The burden of proof for such a claim, if you want to introduce it as an axiom, is on you. And no, the Church-Turing thesis does not prove that claim. As a postulate, I'm happy to accept it for the sake of argument. And if we assume the universe is a Turing machine then sure the existence of human intelligence proves that a Turing Machine can simulate human intelligence and therefore it's computable. Unfortunately, as far as I can tell nothing further follows. Perhaps it's correct, but it's rather dull too.
  - ericjang 5y ago
    > I assume the hidden leg of your rhetorical enthymeme is that the universe is a Turing machine No, I am not making that claim. Not sure how you inferred that. ... by any chance, are you the author of the paper linked in this post? I am asking because I wonder if you are a philosopher by training, rather than being an actual AI researcher. If you are, I wonder if you'd heard of the essay "Newton's Flaming Laser Sword" (https://philosophynow.org/issues/46/Newtons_Flaming_Laser_Sword https://philosophynow.org/issues/46/Newtons_Flaming_Laser_Sw...)
    - User23 5y ago
      I’m not. I’m just an interested layman who likes to read and think. And if I’m really fortunate, to think clearly and distinctly. Evidently then whatever claim it was you were making was not clear to me. I’d be obliged if you made it so. In case it’s not obvious I supposed you implied the universe is a TM on account of that was the first way it occurred to me to make sense of your claim. Incidentally, that Newton’s laser sword monograph was interesting but philosophically rather immature. I think the author would greatly benefit from reading some pragmaticist philosophy, in particular that of C.S. Peirce. Who, by the way, was a mathematician and logician in the Frege tier. Frankly though I do share the author’s disdain for the more navel-gazing pursuits that occupy many contemporary philosophy departments.
jmull 5y ago
You’re making the contradictory claims that human intelligence is incomputable and AI is limited something computable (all by a certain definition of computable). You need to at least try to propose something that explains the premise and the contradiction. Does human intelligence arise out of processes within the human brain? If not, then how else? If yes, then why are those processes somehow out of reach of human science to investigate and manipulate? How can intentional human actions be limited to a certain definition of computability while human intelligence is not?

by User23 5y ago

naasking 5y ago

> Therefore, it's well within the realm of plausibility that the actual behavior of the universe is governed by uncomputable functions, and we are forever stuck modeling those behaviors with computable approximations. Even if the set of uncomputable functions outnumbers the set of of computable functions, I still don't see how your conclusion follows. The rules that govern a coherent universe are not randomly sampled from the set of all functions.

Tzt 5y ago

why not make AI on the same platform as the human brain? what is so exceptional about it, and even if it is an exceptional material, why not just use it?

simonh 5y ago

I don’t see why we have to compute all of reality to create an AI anyway. I’m intelligent, to a point, and I’m pretty sure I don’t compute all reality. My neurological processes simply model enough of reality for me to function more or less effectively, that’s all. The article works from the absurd premise that an AI would have to perfectly model its environment, but no living creatures do this. It also decides that we can’t create general AI because we don’t know how to do it. Therefore it’s impossible. Seriously, it’s right there in the conclusion.

checkyoursudo 5y ago
^ This is really the point. Human intelligence is based on limited and filtered input, rough analog approximations in processing, and incomplete and interpolated mental representations and internal simulations, and yet nobody seriously denies that we possess some degree of intelligence. I am skeptical that current methods will get us to AGI, but the idea that machines must achieve some level of computational perfection far above and beyond humans is not reasonable.
ffwd 5y ago
One thing I think is interesting about the paper is how complex systems (like the brain) change over _time_ rather than at fixed points, and if those changes are computable in any meaningful way. Like if we created an AI 100 years ago, could the AI 100 years later learn how to use an ipad or understand what twitter is or what a meme is? What if brain changes from cultural (environmental) change are both complex and thus creating mathematical models that would change the intelligence of the AI in the way the brain changes is impossible. Like physical changes in the circuits in the brain that are so distributed, interconnected and complicated and subtle yet very specifically "tailored" to the complex system so as to make them virtually impossible to abstract or model in any way, and thus changes the "mathematical model" of the brain that is sort of "virtualized" at a fixed point in time. Edit: Well to put it a little more explicitly: What if the real reason brains are intelligent is not because of the brain alone, but also because of the underlying physical systems like molecules, maybe even going all the way down to quantum mechanics and that those lower levels cause changes over time that fundamentally alters the function of the brain but still has the evolutionary potential of the lower level physical stuff. If you have 2 levels: 1) the brain 2) the underlying physical stuff below neurons 1 is a virtualized fixed point in time that we can model and 2 is part of a complex system that alters 1 but importantly in a way that cannot be computed without simulating that stuff at the lower level. I feel like this is sort of implied in the article because either intelligence can be abstracted completely accurately or there will (as the paper claims) always be lower level physical changes that alters the intelligence in a way that cannot be computed at the brain/intelligence level. I don't know if this is true though tbh

mcguire 5y ago

"Therefore, it's well within the realm of plausibility that the actual behavior of the universe is governed by uncomputable functions..." It's also well within the realm of plausibility that the behavior of the universe is governed by invisible, intangible unicorns. :-) If you can provide an example of something in the universe actually computing an theoretically uncomputable function, then there is a gigantic problem somewhere and everyone is going to have to do some re-thinking. If.

User23 5y ago
By definition nothing will ever compute an uncomputable function. You’re only stating a trivial truth that by itself fails to refute the conjecture that we live in a reality that has behaviors that cannot be accurately described by computable functions and that we are forever stuck with merely approximate computable models. In fact, so far we’re not able to completely computationally predict any behavior of reality. Even the marvelous theory of quantum electrodynamics is only shown to be accurate to, last I knew, about a dozen places. Due to an unfortunately widespread misunderstanding of the Church-Turing thesis, far too many otherwise intelligent persons with some CS knowledge are completely blinkered to the possibility that the universe could have behaviors that are real, but not describable with computable functions beyond approximately. The practicing laboratory scientists I’ve spoken with don’t generally share that defect since they’re used to everything being approximate.
- mannykannot 5y ago
  I think you have a valid point here, but it does not do anything to save this paper. The paper claims to have refuted the possibility of what Searle calls Strong AI, but speculating that the universe has behaviors not describable with computable functions does not justify that conclusion. As Simonh pointed out above [1], Strong AI does not imply or depend on everything about the universe being computable, and even if it did, mere speculation that some unknown thing about the universe might not be computable would not justify inferring that therefore Strong AI must be impossible. This paper is combination of an unargued-for tacit premise with a rather blatant case of burden shifting. [1] https://news.ycombinator.com/item?id=29291286 https://news.ycombinator.com/item?id=29291286

ericjang 5y ago

Whether certain behaviors in the universe are uncomputable or not is irrelevant. If we classify "humans" as intelligent and assume no spooky immaterial aspects of consciousness, you already have an existence proof that intelligence is computable.

User23 5y ago
That doesn't follow from the given premises. I assume the hidden leg of your rhetorical enthymeme is that the universe is a Turing machine. The burden of proof for such a claim, if you want to introduce it as an axiom, is on you. And no, the Church-Turing thesis does not prove that claim. As a postulate, I'm happy to accept it for the sake of argument. And if we assume the universe is a Turing machine then sure the existence of human intelligence proves that a Turing Machine can simulate human intelligence and therefore it's computable. Unfortunately, as far as I can tell nothing further follows. Perhaps it's correct, but it's rather dull too.
- ericjang 5y ago
  > I assume the hidden leg of your rhetorical enthymeme is that the universe is a Turing machine No, I am not making that claim. Not sure how you inferred that. ... by any chance, are you the author of the paper linked in this post? I am asking because I wonder if you are a philosopher by training, rather than being an actual AI researcher. If you are, I wonder if you'd heard of the essay "Newton's Flaming Laser Sword" (https://philosophynow.org/issues/46/Newtons_Flaming_Laser_Sword https://philosophynow.org/issues/46/Newtons_Flaming_Laser_Sw...)
  - User23 5y ago
    I’m not. I’m just an interested layman who likes to read and think. And if I’m really fortunate, to think clearly and distinctly. Evidently then whatever claim it was you were making was not clear to me. I’d be obliged if you made it so. In case it’s not obvious I supposed you implied the universe is a TM on account of that was the first way it occurred to me to make sense of your claim. Incidentally, that Newton’s laser sword monograph was interesting but philosophically rather immature. I think the author would greatly benefit from reading some pragmaticist philosophy, in particular that of C.S. Peirce. Who, by the way, was a mathematician and logician in the Frege tier. Frankly though I do share the author’s disdain for the more navel-gazing pursuits that occupy many contemporary philosophy departments.

jmull 5y ago

You’re making the contradictory claims that human intelligence is incomputable and AI is limited something computable (all by a certain definition of computable). You need to at least try to propose something that explains the premise and the contradiction. Does human intelligence arise out of processes within the human brain? If not, then how else? If yes, then why are those processes somehow out of reach of human science to investigate and manipulate? How can intentional human actions be limited to a certain definition of computability while human intelligence is not?