Computing Machinery and Intelligence

1. Computing Machinery and Intelligence Written by A. M. Turing Summarized by Kim Kyoung-Soo

2. 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?”

3. 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.

4. 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 imaginablecomputers which would do well

5. 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

6. 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

7. 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 calculation • The control • the part which sees that the instructions are obeyed correctly and in the right order

8. 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”

9. 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.

10. 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

11. 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 Last State q1 q2 q3 q2 q3 q1 q1 q2 q3 i0 i1 Input

12. 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)

13. 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

14. 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.

15. 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.

16. 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.

17. 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

18. 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,….

19. 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’.

20. 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

21. 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

22. 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

23. 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.

24. Which Are The Best Ones to Start With? • Abstract activity like the playing of chess • vs. practical activity such as the best sense organs that money can buy, understanding and speaking English, etc.