Part 10 of Turing: a natural philosopher  (1997)

The prospect of intelligent machines

Lady Lovelace's Objection: Our most detailed information of Babbage's Analytical Engine comes from a memoir by Lady Lovelace. In it she states, 'The Analytical Engine has no pretensions to originate anything. It can do whatever we know how to order it to perform.'

This is the cue for a large section on learning machines, with constructive arguments for how machines might do apparently unmechanical things for which explicit programs are unknown: the first public exposition of what I have called his 1941 vision. Turing advocates two different approaches — in modern parlance top-down and bottom-up — which in fact derive from his 1936 descriptions of the machine model. Explicit instruction notes become explicit programming; implicit states of mind become the states of machines attained by learning and self-organizing experience. Turing's positive assurance that machines are capable of all that anyone including himself had done, is illustrated in curiously masochistic self-deprecation, and one passage has a particular resonance:

The view that machines cannot give rise to surprises is due, I believe, to a fallacy to which philosophers and mathematicians are particularly subject. This is the assumption that as soon as a fact is presented to a mind all consequences of that fact spring into the mind simultaneously with it. It is a very useful assumption under many circumstancess, but one too easily forgets that it is false. A natural consequence of doing so is that one assumes that there is no virtue in the mere working out of consequences from data and general principles.

Turing could hardly have typed these words without private allusion to his own contribution ten years earlier, in another world: for his logical breakthrough into the Enigma involved the instantaneous flow of implications, as embodied in ingenious electrical circuitry. He was crediting the mechanical with the capacity for everything, including moments of world-shattering inspiration.

I come now to a raft of questions which arise through the question of how the brain interacts with the external world. Some of these Turing discusses under 'The argument from disabilities', others fall within Jefferson's objections.

The inability to enjoy strawberries and cream may have struck the reader as frivolous. Possibly a machine might be made to enjoy this delicious dish, but any attempt to make one to do so would be idiotic. What is important about this disability is that it contributes to some of the other disabilities, e.g. to the difficulty of the same kind of friendliness occurring between man and machine as between white man and white man, or between black man and black man.

Just as the themes of moral philosophy are hardly met by Turing's theological response, these are somewhat throwaway remarks with which to dispose of the entire content of the social sciences, in which thought and behaviour are considered dominated by external influence. But this was not because Turing was sure of his ground in this case; rather, it is on topics involving interaction that Turing shows himself least certain, anxious about what sensory and motor organs an artificial brain will require. In the development of his thought away from the mathematical calculations of 1936, he allowed first chess, cryptography and (tentatively) languages in the 1948 report as 'topics where not too much interaction is required.' His reference to the machine being denied 'sex, sport and other things of interest to the human being' must have struck an unusual note in the archives of the National Physical Laboratory, and again in the 1948 report Turing distinguishes the concentrating and non-interacting brain from the process of interaction which allows it to learn:

We may say then that in so far as a man is a machine he is one that is subject to very much interference... constantly receiving visual and other stimuli... it is important to remember that although a man when concentrating may behave like a machine without interference, his behaviour when concentrating is largely determined by the way he has been conditioned by previous interference.

Unless the intellectual and physical, internal and external, can be separated, the value of the discrete state machine model of the brain is questionable, for the interface with the ambient world becomes crucial, and the robotic elements need attention as well as the simulation of brain function. In the 1950 paper Turing finally loses all inhibition and throws open the machine to general conversation, but the problem of physical interaction is still an anxiety:

Instead of trying to produce a programme to simulate the adult's mind, why not rather try to produce one which simulates the child's?... It will not be possible to apply exactly the same teaching process to the machine as to a normal child. It will not, for instance, be provided with legs, so that it could not be asked to go out and fill the coal scuttle. Possibly it might not have eyes. But however well these deficiencies might be overcome by clever engineering, we could not send the creature to school without the other children making excessive fun of it. It must be given some tuition. We need not be too concerned about the legs, eyes, etc. The example of Miss Helen Keller shows that education can take place...

These are untypical worries for a mathematician, but then Turing was more natural philosopher than typical mathematician, and the connection between thinking and doing was what had inspired his Turing machine construction in the first place. As his mother had long complained, he could not keep his hands clean.

We may hope that machine will eventually compete with men in all purely intellectual fields. But which are the best ones to start with? ... Many people think that a very abstract activity, like the playing of chess, would be best. It can also be maintained that it is best to provide the machine with the best sense organs that money can buy, and then teach it to understand and speak English... Again I do not know what the right answer is, but I think both approaches should be tried.

© 1997, Andrew Hodges.

CONTINUE to part 11

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