Computing Machinery and Intelligence

Written by A. M. TuringSummarized by Kim Kyoung-Soo

The Imitation Game

The Question: “Can machines think?”Imitation game: the new form of the problem

Played with three people, a man(A), a woman(B), and an interrogator(C)

The interrogator is to determine which of the other two is the man/woman

The question “What will happen when a machine takes the part of A in this game” replace the original question, “Can machines think?”

Critique of the New Problem

“Is the new question a worthy one to investigate?” Drawing a fairly sharp line between the physical

and the intellectual capacities of a man Q ‘n A method excludes the irrelevant disabilities Are the odds weighted too heavily against the

machine?At least, if a machine can, we need not troubled by that.

The Machine Concerned in the Game

To specify what the word “machine” means Only permit digital computers to take part in our

game Ask whether there are imaginable computers

which would do well

The Human Computer

A definition for a “thinking machine” The machines are intended to carry out any

operations which could be done by a “human computer”.

The human computer is supposed to be following fixed rules has the rules supplied in a book has an unlimited supply of paper on which he does

his calculations

Digital Computer

To avoid danger of circularity of argument, we give an outline of the digital computer, using the explanation of the human computer.

Regarded as consisting of three parts(i) Store

(ii) Executive unit

(iii) Control

Three Parts of a Digital Computer

The store a store of information: correspond to the human

computer’s paper or the book of rules(table of instructions)

The executive unit the part which carries out the various individual

operations involved in a calculationThe control

the part which sees that the instructions are obeyed correctly and in the right order

The Information in the Store

Usually broken into packets of moderately small size, e.g. ten decimal digits

“Add the number stored in position 6809 to that in 4302 and put the result back into the latter storage position” ===> ‘6809430217’

“If position 4505 contains 0 obey next the instruction stored in 6707, otherwise continue straight on.”

Constructing instruction tables is described as “programming”

Some Related Issues About D.C.

Digital computer with a random element “Throw a die and put the resulting number into store

1000” Sometimes such a machine is described as having

free will.

Infinitive capacity computers There is no theoretical difficulty in the idea of a

computer with an unlimited store - we can imagine more and more being added as required.

Discrete-State Machine

The digital computers may be classified amongst the “discrete-state machines.”

The discrete-state machine Moves by sudden jumps or clicks from one quite

definite state to another States are sufficiently different for the possibility of

confusion Given the initial state of the machine and the input

signals, it is always possible to predict all future states

Discrete-State Machine(cont’d)

An example of a D-S machine

q1, q2, q3: internal state of the machine

i0, i1: input signal

output signal(light): State q1 q2 q3

Output o0 o0 o1

q2 q3 q1q1 q2 q3

Last State q1 q2 q3

Inputi0

i1

University of Digital Computers

Universal machine A digital computer can mimic the discrete-state

machine’s calculation(to predict what it will do). This special property of digital computers is

described by saying that they are universal machines.

The main question reconsideration see page 19.(CT)

Contrary Views on the Main Question

The theological objection the “Heads in the Sand” objection The mathematical objection The argument from consciousness Arguments from various disabilities Lady Lovelace’s objection Argument from continuity in the nervous system The argument from informality of behaviour The argument from extrasensory perception

The Theological Objection

“Thinking is a function of man’s immortal soul. Hence no animal or machine can think.” The argument quoted above implies a serious

restriction of the omnipotence of the Almighty. We might expect that He would only exercise this

power in conjunction with a mutation which provided the elephant with an appropriately improved brain to minister to the needs of this soul.

The “Heads in the Sand” Objection

“The consequences of machines thinking would be too dreadful. Let us hope and believe that they cannot do so.” We like to believe that Man is in some subtle way

superior to the rest of creation. This argument is sufficiently substantial to require

refutation. Consolation would be more appropriate: perhaps this should be sought in the transmigration of souls.

The Mathematical Objection

A number of results of mathematical logic shows that there are limitations to the powers of discrete-state machines. Ex. Goedel’s theorem(1931)

In any sufficiently powerful logical system, statements can be formulated which can neither be proved ore disproved within the system, unless possibly the system itself is inconsistent.

It has only been stated that no such limitations apply to the human intellect.

The Argument from Consciousness

“A machine can only write it but doesn’t know that it had written it.” It is in fact the solipsist point of view. The only way by which one could be sure that a

machine thinks is to be the machine and to feel oneself thinking.

Likewise according to this view the only way to know that a man thinks is to be that particular man.

Cf. viva voce game

Arguments from Various Disabilities

“You will never be able to make a machine to do X” Be kind, resourceful, make mistakes, enjoy

strawberry and cream, be the subject of its own thought, ……

They are mostly founded on the principle of scientific induction - The machines a man has seen are ugly, designed for a very limited purpose,….

Lady Lovelace’s Objection

Comes from a memoir by Lady Lovelace(1842)

“The Analytical Engine has no pretension to originate anything. It can do whatever we know how to order it to perform” Hartree(1949): “This does not imply that it may

not be possible to construct electronic equipment which will ‘think for itself’, which would serve as a basis for ‘learning’.

Argument from Continuity in the Nervous System

“The nervous system is certainly not a discrete-state machine(continuous system). So a D-S machine cannot mimic the behavior of the nervous system.” A digital computer would be quite capable of

giving the right sort of answer, although it cannot predict exactly what a continuous system answers to a problem. Ex. Differential analyser

The Argument from Informality of Behavior

“It is not possible to produce a set of rules purporting to describe what a man should do in every conceivable set of circumstances.”

“Man has no definite set of rules of conduct by which he regulated his life” We cannot convince ourselves of the absence of

complete laws of behavior as of complete rules of conduct

Learning Machines

Our problem is to find out how to programme these machines to play the game.

Three components of the process The initial state of the mind, say at birth The education to which it has been sujected Other experience

Instead of trying to produce a programme to simulate the adult mind, rather try to produce one which simulates the child’s

Learning Machines(cont’d)

Punishment and rewards events which shortly preceded the occurrence of a

punishment signal are unlikely to repeated a reward signal increased the probability of

repetition of the events

“Unemotional” channels of communication“Human fallibility” is likely to be omitted in a

rather natural way.

Which Are The Best Ones to Start With?

Abstract activity like the playing of chessvs. practical activity such as the best sense

organs that money can buy, understanding and speaking English, etc.