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His sticking point is that the brain or mind could be a physical system that is not computable or equivalent to a Turing machine. If we take the assumption tha

by Leon 17y ago

His sticking point is that the brain or mind could be a physical system that is not computable or equivalent to a Turing machine. If we take the assumption that the mind is a physical system, then it would still only be a matter of time before we found the reason for the difference in computational ability (maybe it would be like Penrose's quantum arguments for the mind), but those systems would still be within reach of implementation within a computer system. The brain is still a combination of proteins, amino acids, and a few other chemicals. We would just have to move to using chemical computers (which are already being researched). Even following his arguments, it would only be a matter of time before sentient machines are created, equivalent to our own minds. His arguments against AI are mostly 'just because' and has little proof.

gruseom 17y ago
A system that is "not computable or equivalent to a Turing machine" is not "within reach of implementation within a computer system". (Unless, of course, the Church-Turing thesis is false. Do you have any evidence of this?)
jacquesm 17y ago
No, his arguments are not 'just because', this is a pretty smart guy and from what I get out of it his reasoning goes like this: If the mind is a physical system then we can attempt to recreate it by computer but this is no guarantee that such an attempt will be successful. For an example of such a situation, imagine that it would take all the resources of a planet in order to create a single AI then it might be theoretically possible but in practice it would fail anyway. And that is assuming that it is possible, for which there is no proof until it is done. If the mind turns out to depend on mechanisms that we can not model accurately enough to get the desired effect then the whole deal is off. There can be no 'proof' that AI is impossible, just as much as there can be no 'proof' that green elephants do not exist. The only proof that would be acceptable is for someone to produce an AI. Nobody needs to present proof that it is not possible.
- Locke1689 17y ago
  Well, that's not entirely true. What is true is that if the mind is more powerful that a Universal Turing Machine, then we have no idea how to approach building one. However, we know that the resources required to build one are small -- humans do it all the time in a relatively cheap process called "sex." That is, the lower bound for creating AI is very small. Of course, the danger is that our brains have certain limitations for a reason -- these could be the property of this super-Universal Turing Machine. Therefore, a true AI may look nothing like our modern computer. The GP is correct in that we should at least be able to build a simulacrum of our own mind -- even if that is simply an artificially constructed duplicate using biology, genetics, and biochemistry. I would say that this may be fairly far away, because we have yet to truly understand many of the processes and structures in the human brain. This is why I believe AI is much farther off than most people think: to understand AI we must first understand ourselves, which is much more complex than at first take. Now, this entire hypothesis rests on the idea that our brain is super-Universal. That is, it cannot be phrased as a computable function (by the Church-Turing thesis). This is a fairly unpopular view in the AI community, but valid until we prove otherwise. Up till now there has been no evidence that such a Turing machine exists in theory, much less in practice, which is a minor blow. In addition, many of our psychological structures and chemical activities seem to suggest a Universal Turing machine. Edit: I just realized that I implied that a super-Universal Turing machine is a Turing machine. This is obviously untrue, by definition. Consider my terminology to be a replacement for whatever name we would give to this noncomputable function solver (since we have no category for that at the moment). Edit2: Not that we don't have a category for noncomputable functions, only that we don't know which category they would fall into. I guess the catch-all "hypercomputable" is suitable. Thanks, naveesunder
  - berntb 17y ago
    >>This is why I believe AI is much farther off than most people think: to understand AI we must first understand ourselves, which is much more complex than at first take. I saw an interview with the director of the Blue Brain project. He projected 10 years, before they can emulate a brain... http://nextbigfuture.com/2009/08/henry-markam-project-director-of-blue.html http://nextbigfuture.com/2009/08/henry-markam-project-direct... "Computational Neuroscience over the past 50 years is a theory driven science, while Blue Brain is biology driven. When we reach the human brain, human-like perceptions and motor actions should emerge automatically. The model brains will be able to learn to do what we human’s can learn to do, perform complex decision-making, manifest emotions, intelligence and personalities. We see these all as straightforward emergent properties of the brain. Self-awareness and consciousness may also emerge if this phenomenon depends on neuronal, synaptic and/or molecular interactions. Anything that depends on the physical elements that can be measured in the brain should emerge if we are successful in building it accurately enough. If we inject some theories of brain while we build it and ignore the biology, then we are back to square one with computational neuroscience and we will almost certainly fail."
thunk 17y ago
If we take the assumption that the mind is a physical system, then it would still only be a matter of time before we found the reason for the difference in computational ability I don't see how the latter follows from the former. The physicality of the mind says nothing of its computability. You're assuming the computationalist axiom that reality is completely computable, which is quite an assumption. The brain is still a combination of proteins, amino acids, and a few other chemicals. We would just have to move to using chemical computers (which are already being researched) We already produce hundreds of thousands of them every day. The process is rather fun. As some point the definition of success has been stretched so far as to be meaningless.

by Leon 17y ago

gruseom 17y ago

A system that is "not computable or equivalent to a Turing machine" is not "within reach of implementation within a computer system". (Unless, of course, the Church-Turing thesis is false. Do you have any evidence of this?)

jacquesm 17y ago

No, his arguments are not 'just because', this is a pretty smart guy and from what I get out of it his reasoning goes like this: If the mind is a physical system then we can attempt to recreate it by computer but this is no guarantee that such an attempt will be successful. For an example of such a situation, imagine that it would take all the resources of a planet in order to create a single AI then it might be theoretically possible but in practice it would fail anyway. And that is assuming that it is possible, for which there is no proof until it is done. If the mind turns out to depend on mechanisms that we can not model accurately enough to get the desired effect then the whole deal is off. There can be no 'proof' that AI is impossible, just as much as there can be no 'proof' that green elephants do not exist. The only proof that would be acceptable is for someone to produce an AI. Nobody needs to present proof that it is not possible.

Locke1689 17y ago
Well, that's not entirely true. What is true is that if the mind is more powerful that a Universal Turing Machine, then we have no idea how to approach building one. However, we know that the resources required to build one are small -- humans do it all the time in a relatively cheap process called "sex." That is, the lower bound for creating AI is very small. Of course, the danger is that our brains have certain limitations for a reason -- these could be the property of this super-Universal Turing Machine. Therefore, a true AI may look nothing like our modern computer. The GP is correct in that we should at least be able to build a simulacrum of our own mind -- even if that is simply an artificially constructed duplicate using biology, genetics, and biochemistry. I would say that this may be fairly far away, because we have yet to truly understand many of the processes and structures in the human brain. This is why I believe AI is much farther off than most people think: to understand AI we must first understand ourselves, which is much more complex than at first take. Now, this entire hypothesis rests on the idea that our brain is super-Universal. That is, it cannot be phrased as a computable function (by the Church-Turing thesis). This is a fairly unpopular view in the AI community, but valid until we prove otherwise. Up till now there has been no evidence that such a Turing machine exists in theory, much less in practice, which is a minor blow. In addition, many of our psychological structures and chemical activities seem to suggest a Universal Turing machine. Edit: I just realized that I implied that a super-Universal Turing machine is a Turing machine. This is obviously untrue, by definition. Consider my terminology to be a replacement for whatever name we would give to this noncomputable function solver (since we have no category for that at the moment). Edit2: Not that we don't have a category for noncomputable functions, only that we don't know which category they would fall into. I guess the catch-all "hypercomputable" is suitable. Thanks, naveesunder
- berntb 17y ago
  >>This is why I believe AI is much farther off than most people think: to understand AI we must first understand ourselves, which is much more complex than at first take. I saw an interview with the director of the Blue Brain project. He projected 10 years, before they can emulate a brain... http://nextbigfuture.com/2009/08/henry-markam-project-director-of-blue.html http://nextbigfuture.com/2009/08/henry-markam-project-direct... "Computational Neuroscience over the past 50 years is a theory driven science, while Blue Brain is biology driven. When we reach the human brain, human-like perceptions and motor actions should emerge automatically. The model brains will be able to learn to do what we human’s can learn to do, perform complex decision-making, manifest emotions, intelligence and personalities. We see these all as straightforward emergent properties of the brain. Self-awareness and consciousness may also emerge if this phenomenon depends on neuronal, synaptic and/or molecular interactions. Anything that depends on the physical elements that can be measured in the brain should emerge if we are successful in building it accurately enough. If we inject some theories of brain while we build it and ignore the biology, then we are back to square one with computational neuroscience and we will almost certainly fail."

thunk 17y ago

If we take the assumption that the mind is a physical system, then it would still only be a matter of time before we found the reason for the difference in computational ability I don't see how the latter follows from the former. The physicality of the mind says nothing of its computability. You're assuming the computationalist axiom that reality is completely computable, which is quite an assumption. The brain is still a combination of proteins, amino acids, and a few other chemicals. We would just have to move to using chemical computers (which are already being researched) We already produce hundreds of thousands of them every day. The process is rather fun. As some point the definition of success has been stretched so far as to be meaningless.