5 ms·

Why Roger Penrose thinks computers can't

34 points by justsee 16y ago

spot 16y ago
Penrose and his book have been debunked. http://www.mth.kcl.ac.uk/~llandau/Homepage/Math/penrose.html http://www.mth.kcl.ac.uk/~llandau/Homepage/Math/penrose.html
- deleted 16y ago
  [deleted]
- justsee 16y ago
  'have been debunked' - quite an emotionally laden phrase to introduce what is in fact an opposing view by another mathematician don't you think? The hostility the Strong AI camp have for Penrose's views is fascinating - it must be infuriating to have such a respected mathematician and physicist take the time to write a few books refuting the reductionist approach. There certainly seems to be no room for a contrarian around those parts! Thanks for the link, but to state that it debunked anything does not seem to be correct. It was an attempted refutation by a computationalist, and Penrose answers these criticims in: http://web.archive.org/web/20080618195657/http://psyche.csse.monash.edu.au/v2/psyche-2-23-penrose.html http://web.archive.org/web/20080618195657/http://psyche.csse... I'd recommend reading the section "4. The "Bare" Gödelian Case". Two particularly relevant points! "4.5 The many arguments that computationalists and other people have presented for wriggling around Gödel's original argument have become known to me only comparatively recently: perhaps we act and perceive according to an unknowable algorithm; perhaps our mathematical understanding is intrinsically unsound; perhaps we could know the algorithms according to which we understand mathematics, but are incapable of knowing the actual roles that these algorithms play. All right, these are logical possibilities. But are they really plausible explanations? 4.6 For those who are wedded to computationalism, explanations of this nature may indeed seem plausible. But why should we be wedded to computationalism? I do not know why so many people seem to be. Yet, some apparently hold to such a view with almost religious fervour. (Indeed, they may often resort to unreasonable rudeness when they feel this position to be threatened!) Perhaps computationalism can indeed explain the facts of human mentality - but perhaps it cannot. It is a matter for dispassionate discussion, and certainly not for abuse! "
  - spot 16y ago
    Did you see where he admits he's wrong? "these are logical possibilities". IE, Penrose made a logical argument, and he didn't cover all the cases. Maybe this one is clearer: http://www.nytimes.com/books/97/04/27/nnp/17540.html http://www.nytimes.com/books/97/04/27/nnp/17540.html
  - shasta 16y ago
    "refuting the reductionist approach" is pretty strong language for describing an argument that's been debunked
- yequalsx 16y ago
  I haven't read the entire article you linked to. Can you elaborate on something? Godel's Incompleteness Theorem (in essence) said that the first order Peano axioms for the integers was not strong enough to prove all statement in the second order Peano axioms. My understanding is that mathematicians wanted a computable system that would be strong enough to prove all true statements encompassed by the second order system. Godel showed this can't be done. No computable system can be strong enough to prove all true statements in the second order system. Given that humans can prove statements that are true in a system that can't be reducible to a computable set of axioms how can computer intelligence ever equal human intelligence? Human intelligence must be fundamentally not a computable system. What's wrong with this reasoning?
  - wlievens 16y ago
    Could you elaborate on "... given that humans can prove statements that are true in a system that can't be reducible to a computable set of axioms ..."? Perhaps with an example?
    - yequalsx 16y ago
      From Wikipedia: The true but unprovable statement referred to by the theorem is often referred to as “the Gödel sentence” for the theory. It is not unique; there are infinitely many statements in the language of the theory that share the property of being true but unprovable.
      - xlpz 16y ago
        How does that prove in any way that the human mind can find all true statements in Mathematics and thus go beyond the limits of computability? Do you have any proof of this? Also, do you have any proof that the human mind is in fact consistent (meaning it can't possibly reach A and ~A at the same time)?
        yequalsx 16y ago
        I'm not claiming that humans can discover all true statements in mathematics. I'm saying the Incompleteness Theorem demonstrates that such a task is not computable and in the proof of the theorem a statement that can't be proven in a computable system is proved. So....can a computer ever reach the same level of reasoning? I'm skeptical.
danbmil99 16y ago
because he's wrong and confused
ntoshev 16y ago
"The question of whether a computer can think is no more interesting than the question of whether a submarine can swim." E. Dijkstra
- hsmyers 16y ago
  So submarines with deformable surfaces and glider technology are what--- chopped liver?
davnola 16y ago
He's a Platonist, so he believes in the existence of a real world that is neither material nor mental. His central claim that conscious acts are in some sense noncomputational is prima facie false. And his concrete solution to problem collects together several other very difficult problems and essentially says, solve one, solve them all. (Great news for his publishers btw.) For those reasons, it's hard to take seriously because it's outrageously speculative.
joubert 16y ago
Thus, Penrose notes, they are true because of their meaning, not because of their syntax relation to an axiomatic system. This reinforces the thesis of Jerrold Katz, that syntactic simples are not semantic simples, and so some truths will depend on semantic contents that cannot be exhaustively expressed as syntax If this were true, would it mean that there are aspects in physics which are not mere abstractions of math?
jacksoncarter 16y ago
The argument that computers can't think derives from the idea that there are noncomputational processes at work in the brain. Essentially, we don't know how certain thoughts arrive in our mind. We can't create an algorithm to mimic our chain-of-thought generator. But that doesn't mean we can't create a computer that can have similar noncomputational "thoughts". People must choose, when a computer need not choose. What I mean is, a computer can shut down. A human mind cannot -- and continue to live. When a computer "observes" -- so to speak -- stimuli it cannot handle or are beyond its capacity, it does not make random choices about what to do now. We do not trust randomness. Sometimes, however, humans have no option but randomness. This is why in a crowd of 100 each one will react differently to the same stimulus. If it suddenly gets very cold, some will shiver, some will leave, some will get up and jump around. In most cases, Computer systems aren't even allowed to accept input that isn't known to be valid. Minds have to all the time. When you begin to predict the future and that's largely what the human mind is -- a future prediction machine, then it becomes even more complex. It requires memory. Concoctions from memory or assumptions. We don't let computers assume. In many ways, we are holding computers back. Because we are afraid. We are afraid of what they will decide for us. We are afraid of random. We need control. We haven't subjected computers to survival of the fittest. If we did, then by the law of large numbers, eventually, like I suppose is true with many humans, one will survive that we can't explain how. We won't know how that computer made all the right decisions the whole time. We don't know how to program computers to accept any input. White is the maximum color. Black is the darkest. But computers could see much darker than black and much brighter than white. How can we control something like that? We can't. We won't be able to. It will see and know thinks we can't imagine. It's silly to think computers can't.
- Symmetry 16y ago
  "People must choose, when a computer need not choose." Perhaps I'm not understanding something, but that seems to be obviously false. A human always has the option of being unsure in the face of non-computable statements like "You can't know that this sentence is true" or such.
  - jacksoncarter 16y ago
deleted 16y ago
[deleted]
varjag 16y ago
Patricia Smith Churchland has famously remarked about Penrose's theories that "Pixie dust in the synapses is about as explanatorily powerful as quantum coherence in the microtubules." http://en.wikipedia.org/wiki/Hard_problem_of_consciousness#Scientific_attempts http://en.wikipedia.org/wiki/Hard_problem_of_consciousness#S...
- zephjc 16y ago
  Pretty much. Penrose, despite being generally brilliant, is not an expert in neuroscience. QM explanations seem like hand waving or saying "we don't really know, and since I know a lot about QM, that must be the reason". It's almost avoiding investigation into the hard problems of neurobiology to find the real, physical processes that bring about human cognition.
mark_l_watson 16y ago
I bought and read "The Emperor's New Mind" in the early 90s, mostly for "knowing your enemy." I have slowly but surely come to mostly agree with Penrose: I think there is something magical and "quantum mechanical" about brain consciousness (including animals). I believe in eventual real AI, but I would guess that it will not be on current computer hardware.
- ugh 16y ago
  Why is quantum physics magical? Or is that not what you wanted to say? As far as I know we have a pretty clear understanding of quantum physics.
  - mark_l_watson 16y ago
    I only have a BS in Physics (UCSB) so this may be rough: about 10 years ago I went to a Quantum Mechanics and Consciousness conference and the gist is that there is a quantum effect that is required consciousness. My dad taught physics at Berkeley and his friend from Berkeley Henry Stapp presented an interesting paper on this theory. The philosopher David Chalmers was also there and he talked about the difficult question of consciousness: why did evolution favor the development of consciousness and qualia (an inner mental life)?
    - Symmetry 16y ago
      There are several obvious explanations like that we evolved conciousness in order to be able to explain ourselves to other humans. But I thought Chalmers believe that the physical world was "causally closed" and that therefore a purely material feedback process like evolution couldn't select for qualia?
ugh 16y ago
Check out the awesome Gödel CAPTCHA (linked from the article): http://www.scottaaronson.com/writings/captcha.html http://www.scottaaronson.com/writings/captcha.html Yay! No more spam.
Symmetry 16y ago
I was annoyed at how the article just blithely asserted that wavefunctions collapse, as if that wasn't a matter of ongoing debate. In fact, Penrose is remarkable among big name physicists for being sure that wavefrom collapse occurs. http://www.hedweb.com/manworld.htm#believes http://www.hedweb.com/manworld.htm#believes
waveman 16y ago
This is a classic Dunning-Kruger situation. Penrose is out of domain of expertise here. He has not bothered to study the theory of mind (eg see the lack of relevant references in his book). His arguments do not stack up, as extensively documented elsewhere. This is not the first time that a famous physicist/mathematician has got it drastically. Neils Bohr was an animist - he believed along with many people at the time that there was some magic hidden essence to life that went beyond material things. When told about the discovery of DNA he said "Yes, but where is the life?".
- gruseom 16y ago
  Personally my sympathies are with Penrose and Bohr.

34 points by justsee 16y ago

spot 16y ago

Penrose and his book have been debunked. http://www.mth.kcl.ac.uk/~llandau/Homepage/Math/penrose.html http://www.mth.kcl.ac.uk/~llandau/Homepage/Math/penrose.html

deleted 16y ago
[deleted]
justsee 16y ago
'have been debunked' - quite an emotionally laden phrase to introduce what is in fact an opposing view by another mathematician don't you think? The hostility the Strong AI camp have for Penrose's views is fascinating - it must be infuriating to have such a respected mathematician and physicist take the time to write a few books refuting the reductionist approach. There certainly seems to be no room for a contrarian around those parts! Thanks for the link, but to state that it debunked anything does not seem to be correct. It was an attempted refutation by a computationalist, and Penrose answers these criticims in: http://web.archive.org/web/20080618195657/http://psyche.csse.monash.edu.au/v2/psyche-2-23-penrose.html http://web.archive.org/web/20080618195657/http://psyche.csse... I'd recommend reading the section "4. The "Bare" Gödelian Case". Two particularly relevant points! "4.5 The many arguments that computationalists and other people have presented for wriggling around Gödel's original argument have become known to me only comparatively recently: perhaps we act and perceive according to an unknowable algorithm; perhaps our mathematical understanding is intrinsically unsound; perhaps we could know the algorithms according to which we understand mathematics, but are incapable of knowing the actual roles that these algorithms play. All right, these are logical possibilities. But are they really plausible explanations? 4.6 For those who are wedded to computationalism, explanations of this nature may indeed seem plausible. But why should we be wedded to computationalism? I do not know why so many people seem to be. Yet, some apparently hold to such a view with almost religious fervour. (Indeed, they may often resort to unreasonable rudeness when they feel this position to be threatened!) Perhaps computationalism can indeed explain the facts of human mentality - but perhaps it cannot. It is a matter for dispassionate discussion, and certainly not for abuse! "
- spot 16y ago
  Did you see where he admits he's wrong? "these are logical possibilities". IE, Penrose made a logical argument, and he didn't cover all the cases. Maybe this one is clearer: http://www.nytimes.com/books/97/04/27/nnp/17540.html http://www.nytimes.com/books/97/04/27/nnp/17540.html
- shasta 16y ago
  "refuting the reductionist approach" is pretty strong language for describing an argument that's been debunked
yequalsx 16y ago
I haven't read the entire article you linked to. Can you elaborate on something? Godel's Incompleteness Theorem (in essence) said that the first order Peano axioms for the integers was not strong enough to prove all statement in the second order Peano axioms. My understanding is that mathematicians wanted a computable system that would be strong enough to prove all true statements encompassed by the second order system. Godel showed this can't be done. No computable system can be strong enough to prove all true statements in the second order system. Given that humans can prove statements that are true in a system that can't be reducible to a computable set of axioms how can computer intelligence ever equal human intelligence? Human intelligence must be fundamentally not a computable system. What's wrong with this reasoning?
- wlievens 16y ago
  Could you elaborate on "... given that humans can prove statements that are true in a system that can't be reducible to a computable set of axioms ..."? Perhaps with an example?
  - yequalsx 16y ago
    From Wikipedia: The true but unprovable statement referred to by the theorem is often referred to as “the Gödel sentence” for the theory. It is not unique; there are infinitely many statements in the language of the theory that share the property of being true but unprovable.
    - xlpz 16y ago
      How does that prove in any way that the human mind can find all true statements in Mathematics and thus go beyond the limits of computability? Do you have any proof of this? Also, do you have any proof that the human mind is in fact consistent (meaning it can't possibly reach A and ~A at the same time)?
      - yequalsx 16y ago
        I'm not claiming that humans can discover all true statements in mathematics. I'm saying the Incompleteness Theorem demonstrates that such a task is not computable and in the proof of the theorem a statement that can't be proven in a computable system is proved. So....can a computer ever reach the same level of reasoning? I'm skeptical.

danbmil99 16y ago

because he's wrong and confused

ntoshev 16y ago

"The question of whether a computer can think is no more interesting than the question of whether a submarine can swim." E. Dijkstra

hsmyers 16y ago
So submarines with deformable surfaces and glider technology are what--- chopped liver?

davnola 16y ago

He's a Platonist, so he believes in the existence of a real world that is neither material nor mental. His central claim that conscious acts are in some sense noncomputational is prima facie false. And his concrete solution to problem collects together several other very difficult problems and essentially says, solve one, solve them all. (Great news for his publishers btw.) For those reasons, it's hard to take seriously because it's outrageously speculative.

joubert 16y ago

Thus, Penrose notes, they are true because of their meaning, not because of their syntax relation to an axiomatic system. This reinforces the thesis of Jerrold Katz, that syntactic simples are not semantic simples, and so some truths will depend on semantic contents that cannot be exhaustively expressed as syntax If this were true, would it mean that there are aspects in physics which are not mere abstractions of math?

jacksoncarter 16y ago

The argument that computers can't think derives from the idea that there are noncomputational processes at work in the brain. Essentially, we don't know how certain thoughts arrive in our mind. We can't create an algorithm to mimic our chain-of-thought generator. But that doesn't mean we can't create a computer that can have similar noncomputational "thoughts". People must choose, when a computer need not choose. What I mean is, a computer can shut down. A human mind cannot -- and continue to live. When a computer "observes" -- so to speak -- stimuli it cannot handle or are beyond its capacity, it does not make random choices about what to do now. We do not trust randomness. Sometimes, however, humans have no option but randomness. This is why in a crowd of 100 each one will react differently to the same stimulus. If it suddenly gets very cold, some will shiver, some will leave, some will get up and jump around. In most cases, Computer systems aren't even allowed to accept input that isn't known to be valid. Minds have to all the time. When you begin to predict the future and that's largely what the human mind is -- a future prediction machine, then it becomes even more complex. It requires memory. Concoctions from memory or assumptions. We don't let computers assume. In many ways, we are holding computers back. Because we are afraid. We are afraid of what they will decide for us. We are afraid of random. We need control. We haven't subjected computers to survival of the fittest. If we did, then by the law of large numbers, eventually, like I suppose is true with many humans, one will survive that we can't explain how. We won't know how that computer made all the right decisions the whole time. We don't know how to program computers to accept any input. White is the maximum color. Black is the darkest. But computers could see much darker than black and much brighter than white. How can we control something like that? We can't. We won't be able to. It will see and know thinks we can't imagine. It's silly to think computers can't.

Symmetry 16y ago
"People must choose, when a computer need not choose." Perhaps I'm not understanding something, but that seems to be obviously false. A human always has the option of being unsure in the face of non-computable statements like "You can't know that this sentence is true" or such.
- jacksoncarter 16y ago

deleted 16y ago

[deleted]

varjag 16y ago

Patricia Smith Churchland has famously remarked about Penrose's theories that "Pixie dust in the synapses is about as explanatorily powerful as quantum coherence in the microtubules." http://en.wikipedia.org/wiki/Hard_problem_of_consciousness#Scientific_attempts http://en.wikipedia.org/wiki/Hard_problem_of_consciousness#S...

zephjc 16y ago
Pretty much. Penrose, despite being generally brilliant, is not an expert in neuroscience. QM explanations seem like hand waving or saying "we don't really know, and since I know a lot about QM, that must be the reason". It's almost avoiding investigation into the hard problems of neurobiology to find the real, physical processes that bring about human cognition.

mark_l_watson 16y ago

I bought and read "The Emperor's New Mind" in the early 90s, mostly for "knowing your enemy." I have slowly but surely come to mostly agree with Penrose: I think there is something magical and "quantum mechanical" about brain consciousness (including animals). I believe in eventual real AI, but I would guess that it will not be on current computer hardware.

ugh 16y ago
Why is quantum physics magical? Or is that not what you wanted to say? As far as I know we have a pretty clear understanding of quantum physics.
- mark_l_watson 16y ago
  I only have a BS in Physics (UCSB) so this may be rough: about 10 years ago I went to a Quantum Mechanics and Consciousness conference and the gist is that there is a quantum effect that is required consciousness. My dad taught physics at Berkeley and his friend from Berkeley Henry Stapp presented an interesting paper on this theory. The philosopher David Chalmers was also there and he talked about the difficult question of consciousness: why did evolution favor the development of consciousness and qualia (an inner mental life)?
  - Symmetry 16y ago
    There are several obvious explanations like that we evolved conciousness in order to be able to explain ourselves to other humans. But I thought Chalmers believe that the physical world was "causally closed" and that therefore a purely material feedback process like evolution couldn't select for qualia?

ugh 16y ago

Check out the awesome Gödel CAPTCHA (linked from the article): http://www.scottaaronson.com/writings/captcha.html http://www.scottaaronson.com/writings/captcha.html Yay! No more spam.

Symmetry 16y ago

I was annoyed at how the article just blithely asserted that wavefunctions collapse, as if that wasn't a matter of ongoing debate. In fact, Penrose is remarkable among big name physicists for being sure that wavefrom collapse occurs. http://www.hedweb.com/manworld.htm#believes http://www.hedweb.com/manworld.htm#believes

waveman 16y ago

This is a classic Dunning-Kruger situation. Penrose is out of domain of expertise here. He has not bothered to study the theory of mind (eg see the lack of relevant references in his book). His arguments do not stack up, as extensively documented elsewhere. This is not the first time that a famous physicist/mathematician has got it drastically. Neils Bohr was an animist - he believed along with many people at the time that there was some magic hidden essence to life that went beyond material things. When told about the discovery of DNA he said "Yes, but where is the life?".

gruseom 16y ago
Personally my sympathies are with Penrose and Bohr.