Download Computing Machinery & Intelligence

Cognitive Computing
2012
The computer and the mind
1. TURING
Professor Mark Bishop
“Can machines really think?”
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This was a question posed in a seminal paper published by Alan Turing,
(1950), Computing Machinery & Intelligence, Mind, LIX 2236.
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Reprinted in, Boden, M., The Philosophy of Artificial Intelligence, OUP.
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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..
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The Imitation Game
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A man (M) and a woman (W) are in two separate rooms.
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Outside the room there is an interrogator.
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The interrogator asks questions of both the man and the woman using the written word
alone.
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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.
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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).
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And the interrogator simply has to determine which respondent is the
human and which is the machine.
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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’
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Turing’s 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:
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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".
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Other possible Turing tests…


A close reading of Turing’s 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 the
‘woman’;

(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 Turing’s writing supports the ‘standard
interpretation’
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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.
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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;
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(b) that the interrogator knows that one of the
respondents is a machine;
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(c) that the respondents can lie.
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Turing’s predictions

In the 1950 paper Turing confidently predicted that by the year 2000 there
would be computers with 1G of storage
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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?
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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…
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The 2008 Reading Loebner Prize
Event
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The 2008 Loebner Prize put Turing’s 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:
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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.
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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 Cleverbot’s
responses to be human; for comparison 63.3% assessed the human responses to be human!
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The future of the Turing test ..
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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.
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Perhaps the most well known critic of Turing's methodology is John Searle
in his famous Chinese Room Argument, (CRA).
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The Chinese Room Argument
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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.
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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.
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Turing’s objections to machine
intelligence (1)
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Theological Objection
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Thinking is a function of the soul granted only to
man & woman!
‘Heads in sand’
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The concept is too appalling so lets believe its
impossible!
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Turing’s objections to machine
intelligence (2)
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The Mathematical Objection
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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”.
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Lucas, (1961), Minds, Machines & Godel, Philosophy, 36.
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Basically there are statements from which outside the system can be seen to be
true, but which cannot be proved true within the system.
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eg. The Godel formula of the system.
The Godel formula of the system.
The mathematical argument is linked to the concept that intelligence may
not be a computable function ...
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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. 145.
 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.
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Turing’s objections to machine
intelligence (3)
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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!
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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.

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But this position makes conversation difficult!
Current Disabilities
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Machine can do Tasks {W,X,Y} but not {Z}...
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Turing’s objections to machine
intelligence (4)
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Lady Lovelace’s objection (regarding Babbage’s Analytical Engine)
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It has no pretensions to originate anything, it just does what we tell it.
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But what is newness?
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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
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The nervous system is analogue and continuous, computers are not.
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Computers can synthesise analogue behaviour to any finite specified
accuracy & probability.
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Turing’s objections to machine
intelligence (5)
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Informality of behaviour (free will & determinism)
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‘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 !!
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People have ESP, machines certainly don’t.
At the time of Turing’s 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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