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Cognitive Computing 2012 The computer and the mind 1. TURING Professor Mark Bishop.

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1 Cognitive Computing 2012 The computer and the mind 1. TURING Professor Mark Bishop

2 01/04/2014(c) Bishop: The philosophy of A.I. & A-Life2 Can machines really think? This was a question posed in a seminal paper published by Alan Turing, (1950), Computing Machinery & Intelligence, Mind, LIX Reprinted in, Boden, M., The Philosophy of Artificial Intelligence, OUP. In the paper Turing famously stated that he believed this question far too vague and ill defined for proper scientific study and so he recast it in the form of a procedure that has since become known as the Turing Test, which was based on Turing imagining something like an old Victorian parlour game.. The Imitation Game A man (M) and a woman (W) are in two separate rooms. Outside the room there is an interrogator. The interrogator asks questions of both the man and the woman using the written word alone. The object of the game is for the interrogator to determine which of his two correspondents is the woman - and which is the man - purely on the basis of these text only interactions.

3 01/04/2014(c) Bishop: The philosophy of A.I. & A-Life3 The Turing test We now ask the question, 'What will happen when a machine takes the part of the man (M) in this game?' Will the interrogator decide wrongly as often when the game is played like this as he does when the game is played between a man and a woman? These questions replace our original, 'Can machines think? Thus, in - the standard interpretation of - the Turing Test, a computer takes the part of either the man (M) or woman (W). And the interrogator simply has to determine which respondent is the human and which is the machine. Would the interrogator decide wrongly as often as in the Imitation Game? If so we might now say that the machine has passed the Turing Test

4 Turings 1948 chess test In a 1948 paper Intelligent Machinery, (Turing, A.M. (1948). National Physical Laboratory Report, 1948, re-printed in Copeland, B.J. (ed) (2004) The Essential Turing, Oxford & New York: Oxford University Press). Turing presents an early version of the Turing test. In this version, instead of a human having to judge between a machine-computer and a human, the interrogator has to differentiate between a human following-a-rule-book playing chess and a conventional human chess player: Turing: "It is possible to do a little experiment on these lines, even at the present stage of knowledge. It is not difficult to devise a paper machine which will play a not very bad game of chess. Now get three men as subjects for the experiment A, B, and C. A and C are to be rather poor chess players, B is the operator who works the paper machine. (ln order that he should be able to work it fairly fast it is advisable that he be both mathematician and chess player.) Two rooms are used with some arrangement for communicating moves, and a game is played between C and either A or the paper machine. C may find it quite difficult to tell which he is playing". 01/04/2014(c) Bishop: The philosophy of A.I. & A-Life4

5 Other possible Turing tests… A close reading of Turings words in the 1950 paper reveals that there are other possible interpretations of his procedure, such as: (a) the computer, taking the part of the man in the imitation game, while the other participant is a woman, has to fool the interrogator that it is thewoman; (b) the computer, taking the part of the man, has fool the interrogator that it is female and the other player is a male who has to fool the interrogator that he is female. However the main body of Turings writing supports the standard interpretation And in any event it has been demonstrated (Moor, J. (2001), The Status and Future of the Turing Test, Minds and Machines, 11: 77–93.) that there is no reason to suppose these other interpretations would lead to a better test. 01/04/2014(c) Bishop: The philosophy of A.I. & A-Life5

6 01/04/20146 Remarks on the Turing Test The subtleties of the Turing Test include the facts that: (a) that the interrogator is allowed to ask questions which range over the entire human condition; (b) that the interrogator knows that one of the respondents is a machine; (c) that the respondents can lie.

7 Turings predictions In the 1950 paper Turing confidently predicted that by the year 2000 there would be computers with 1G of storage And in this Turing was correct. And there would be computers which would be able to perform the Turing Test such that the average interrogator in a Turing Test would not have more than 70% chance of making the right identification after five minutes of questioning. Unfortunately this prediction is also ambiguous: did Turing mean a five minute test, or did he mean five minutes of questioning per respondent? If the latter, then the test itself would take ten minutes; if the former then it would take five. But in either case Turing has yet to be proven correct… 01/04/20147

8 The 2008 Reading Loebner Prize Event The 2008 Loebner Prize put Turings prediction to the test in the first manner by having five minute Turing Tests. That is, the Interrogator was allowed a total of five minutes to respond to both entities (the human and the computer). As a consequence the expected interaction time with the computer program was two and a half minutes. However even this five minute claim has so far proved optimistic: In the 2008 Loebner Prize Event (held at the University of Reading, UK) even the best computer program - Elbot, Fred Roberts and Artificial Solutions - 'fooled only 25% of the interrogators. Hence, as of 2008, we still fall short of the 30% Turing predicted. NB. Techniche festival at the Indian Institute of Technology Guwahati on September 3, 2011, India, New Scientist reported that a modified version of the Turing Test had been passed. In this version 30 volunteers interact with either CLEVERBOT or a human and an audience are asked to vote on which they believe it to be. Out of an audience of 1334, over 4 minute interactions 59.3% of the audience assessed Cleverbots responses to be human; for comparison 63.3% assessed the human responses to be human! 01/04/20148

9 The future of the Turing test.. Nonetheless it seems very likely that in the next few years Turing's predictions for a 'time limited' Turing Test will be met. Whether this means that at that juncture general educated opinion will have altered so much that one will be able to speak of machines thinking without expecting to be contradicted, as Turing asserted, is very doubtful.. This is because in the 50+ years since the paper was first published, the methodology behind the Turing Test has been extensively criticized. Perhaps the most well known critic of Turing's methodology is John Searle in his famous Chinese Room Argument, (CRA). 01/04/20149

10 The Chinese Room Argument The CRA purports to show that even if a computer behaved in a manner indistinguishable from a human it cannot be genuinely said to understand its responses and hence the computer still cannot be genuinely said to think. See Searle, J. (1981), Minds, Brains, and Programs, Behavioral and Brain Sciences, 3: 417–57; and for recent discussion Preston, J. and M. Bishop (eds.), 2002, Views into the Chinese Room: New Essays on Searle and Artificial Intelligence, New York: Oxford University Press). At the Exeter 2013 AISB convention there will be a special symposium on Turing and the Turing test. 01/04/2014(c) Bishop: The philosophy of A.I. & A-Life10

11 01/04/2014(c) Bishop: The philosophy of A.I. & A-Life11 Turings objections to machine intelligence (1) Theological Objection Thinking is a function of the soul granted only to man & woman! Heads in sand The concept is too appalling so lets believe its impossible!

12 01/04/2014(c) Bishop: The philosophy of A.I. & A-Life12 Turings objections to machine intelligence (2) The Mathematical Objection From Godel, in any sufficiently powerfully logical system, statements can be formulated which can neither be proved or disproved within the system, unless possibly the system itself is inconsistent. eg. The Godel formula of the system. Lucas, (1961), Minds, Machines & Godel, Philosophy, 36. Basically there are statements from which outside the system can be seen to be true, but which cannot be proved true within the system. The Godel formula of the system. The mathematical argument is linked to the concept that intelligence may not be a computable function...

13 01/04/2014(c) Bishop: The philosophy of A.I. & A-Life13 The Mathematical objection (2) Benacerraf, P., (1967), God, the Devil & Godel, Monist, 51. Could a machine convince itself of the truth of such formulae? It is not clear from Godel that it could not. Further, perhaps another machine, like me, could out Godel the machine that claimed to be I? Lucas, (1968), Satan Stultified: A Rejoinder to Paul Benacerraf, Monist, 52, pp Lucas is not claiming that the mind is somehow greater than all possible machines but that for any given machine there is something he can do that it cannot. Lucas is not claiming that his argument proves that mind is more than machine, but that it is a schema for disproof for any particular version of mechanism (the claim that I am a machine) that may be put forward.

14 01/04/2014(c) Bishop: The philosophy of A.I. & A-Life14 Turings objections to machine intelligence (3) Consciousness - No machine can feel pain; if my leg is chopped off by a mad axe-man, I don't feel abstract pain. e.g. pain := pain + 6! Solipsist argument; how do I know anyone genuinely feels pain? As the only way to know that a man thinks is to be that man. But this position makes conversation difficult! Current Disabilities Machine can do Tasks {W,X,Y} but not {Z}...

15 01/04/2014(c) Bishop: The philosophy of A.I. & A-Life15 Turings objections to machine intelligence (4) Lady Lovelaces objection (regarding Babbages Analytical Engine) It has no pretensions to originate anything, it just does what we tell it. But what is newness? Ecclesiastes 1.9, The thing that hath been, it is that which shall be: And that which is done is that which shall be done: And there is no new thing under the sun. In research are we not building on what has gone before? Standing on the shoulders of giants Analogue from the nervous system The nervous system is analogue and continuous, computers are not. Computers can synthesise analogue behaviour to any finite specified accuracy & probability.

16 01/04/2014(c) Bishop: The philosophy of A.I. & A-Life16 Turings objections to machine intelligence (5) Informality of behaviour (free will & determinism) Man does function to Explicit rules. But how do we know? A combination of even very simple rules can appear very complicated, (cf. fruit-machines). cf. Morden, M., Free will, Self-causation & Strange Loops, Australasian Journal of Philosophy, 68:1. The argument from ESP !! People have ESP, machines certainly dont. At the time of Turings paper, there was a widespread belief in ESP among the scientific community, due to some widely publicised, but statistical flawed, work on ESP.


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