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[I]t depends on whether or not there's an algorithm for everything. We already know that there is not an algorithm for everything. Indeed, Turing himself showe

[I]t depends on whether or not there's an algorithm for everything. We already know that there is not an algorithm for everything. Indeed, Turing himself showed that there is not an algorithm for solving the halting problem <http://en.wikipedia.org/wiki/Halting_problem> http://en.wikipedia.org/wiki/Halting_problem>. But that has no bearing on whether or not there exists an algorithm that would someday allow a computer to pass the Turing Test.

gruseom 19y ago
Replace that phrase with algorithm for everything that's intrinsic to being human. Or, if you prefer, algorithm for everything necessary to simulate being human sufficiently well to consistently fool humans via low-bandwidth TTY. My point remains the same: it's a belief either way. And throwing processing power at it will only yield the predicted effect in one of those cases. Edit: the existence of undecidability results (and the general failure of the formalist project) ought to make us more, not less skeptical of grandiose claims concerning computability.
- bumbledraven 19y ago
  [I]t depends on whether or not there's an algorithm for everything necessary to simulate being human sufficiently well to consistently fool humans via low-bandwidth TTY. But clearly such an algorithm does exist, so this objection fails. Its existence follows from these facts: (1) only a fixed amount of data in the form of questions can flow through the low-bandwidth TTY, (2) only a fixed amount of data in the form of responses can be sent back back, and (3) there exists an algorithm for any function with a bounded input and output. (To see this, note that the algorithm could consist of a lookup table containing a correct output for each of the finite number of inputs it has to deal with.) I concede that it is another matter entirely whether or not we will ever discover such an algorithm and implement it on a sufficiently powerful computer. But the fact that an algorithm for passing the Test must exist takes the discussion out of the realm of physical and/or philosophical possibility and into the realm of technology and engineering.
  - gruseom 19y ago
    Uh oh, you got technical on me! It's been a long time since I've studied this stuff, but for what it's worth, your argument feels incorrect to me. It might not be possible to address that effectively here, but let me try. Let's call a particular run of the Turing test a "Turing dialog". Say a Turing dialog D consists of alternating statements C1,H1,...,Cn,Hn where C stands for "computer" and H for "human". Say a "successful Turing dialog" is one that succeeds in fooling the human participant - that is, Hn is something like "I think you're human". You're right that for any Turing dialog D, D is finite and therefore an algorithm exists to reproduce it (a simple lookup table will do). But such an algorithm is only good for one specific D. To build it, you'd have to know all of D in advance. To pass the Turing test, we need more. We need an algorithm, which, given any valid prefix of a Turing dialog, i.e. any sequence C1,H1,...,Ck,Hk, knows how to produce Ck+1 in such a way that the dialog will end successfully. That's not the same thing, is it?
    - bumbledraven 19y ago
      We need an algorithm, which, given any valid prefix of a Turing dialog, i.e. any sequence C1,H1,...,Ck,Hk, knows how to produce Ck+1 in such a way that the dialog will end successfully. Exactly, but since each Turing dialog is of bounded length (i.e. no more than a megabyte in size, depending on the bandwidth of the TTY and the predetermined maximum length of the test), the set of all Turing dialogs is finite and is therefore subject to the dictionary algorithm approach. It's rather like building out the game tree of optimal play for White in chess. The tree for the Turing Test "game" would have to include all the questions that could be asked at each point in the tree, but you only need one possible correct ("Turing-test passing") response at each node.

gruseom 19y ago

Replace that phrase with algorithm for everything that's intrinsic to being human. Or, if you prefer, algorithm for everything necessary to simulate being human sufficiently well to consistently fool humans via low-bandwidth TTY. My point remains the same: it's a belief either way. And throwing processing power at it will only yield the predicted effect in one of those cases. Edit: the existence of undecidability results (and the general failure of the formalist project) ought to make us more, not less skeptical of grandiose claims concerning computability.

bumbledraven 19y ago
[I]t depends on whether or not there's an algorithm for everything necessary to simulate being human sufficiently well to consistently fool humans via low-bandwidth TTY. But clearly such an algorithm does exist, so this objection fails. Its existence follows from these facts: (1) only a fixed amount of data in the form of questions can flow through the low-bandwidth TTY, (2) only a fixed amount of data in the form of responses can be sent back back, and (3) there exists an algorithm for any function with a bounded input and output. (To see this, note that the algorithm could consist of a lookup table containing a correct output for each of the finite number of inputs it has to deal with.) I concede that it is another matter entirely whether or not we will ever discover such an algorithm and implement it on a sufficiently powerful computer. But the fact that an algorithm for passing the Test must exist takes the discussion out of the realm of physical and/or philosophical possibility and into the realm of technology and engineering.
- gruseom 19y ago
  Uh oh, you got technical on me! It's been a long time since I've studied this stuff, but for what it's worth, your argument feels incorrect to me. It might not be possible to address that effectively here, but let me try. Let's call a particular run of the Turing test a "Turing dialog". Say a Turing dialog D consists of alternating statements C1,H1,...,Cn,Hn where C stands for "computer" and H for "human". Say a "successful Turing dialog" is one that succeeds in fooling the human participant - that is, Hn is something like "I think you're human". You're right that for any Turing dialog D, D is finite and therefore an algorithm exists to reproduce it (a simple lookup table will do). But such an algorithm is only good for one specific D. To build it, you'd have to know all of D in advance. To pass the Turing test, we need more. We need an algorithm, which, given any valid prefix of a Turing dialog, i.e. any sequence C1,H1,...,Ck,Hk, knows how to produce Ck+1 in such a way that the dialog will end successfully. That's not the same thing, is it?
  - bumbledraven 19y ago
    We need an algorithm, which, given any valid prefix of a Turing dialog, i.e. any sequence C1,H1,...,Ck,Hk, knows how to produce Ck+1 in such a way that the dialog will end successfully. Exactly, but since each Turing dialog is of bounded length (i.e. no more than a megabyte in size, depending on the bandwidth of the TTY and the predetermined maximum length of the test), the set of all Turing dialogs is finite and is therefore subject to the dictionary algorithm approach. It's rather like building out the game tree of optimal play for White in chess. The tree for the Turing Test "game" would have to include all the questions that could be asked at each point in the tree, but you only need one possible correct ("Turing-test passing") response at each node.