Alan Turing: The Enigma (98 page)

Alan asked Arnold where he was going and Arnold replied ‘nowhere special’. So Alan invited him to lunch in the restaurant across the road. Fair and with blue eyes, undernourished and with his thin hair already receding, desperate for better things and more receptive than so many educated people, Arnold touched Alan’s soft spot for lost lambs, as well as other chords. He also had a determined vivacity and a saving sense of humour that could carry him through the most difficult situations. Alan told him that .he had to go back to the university, where he was a lecturer, and explained that he worked on the Electronic Brain. Arnold was fascinated; Alan asked him to come to his home at Wilmslow at the weekend. By making invitations to lunch and to his home, Alan
had already offered a good deal more than would usually be expected of a street encounter, where a quick adjournment to railway arch, back alley or toilet would be more customary. Arnold accepted the invitation, but then failed to appear on the night.

This might easily have been the end of the matter, but Alan saw Arnold again on Oxford Street on the next Monday afternoon. Arnold offered a feeble excuse for his failure to appear, and this time Alan invited him home immediately. Arnold did as Alan suggested, stayed until the late evening, and agreed to come another time on 12 January. Alan sent him a pen-knife as a Christmas present.

The BBC Third Programme had now arranged for a sort of
Brains’ Trust
on the subject of whether machines could be said to think.
^*
Sometime near Christmas 1951, Alan visited David Champernowne at Oxford. He had an early tape recorder, and they made a spoof version of the discussion, with Champ putting on the Arts Man voice appropriate to the discussion of beauty and other high-minded concepts to which the machine could not aspire. Fred Clayton came later and was duly fooled. He, meanwhile, had got married, just as he said he would, and had been fortunate in his appointment to a lectureship in classics at the University College at Exeter. He was much concerned with developing a thesis about parallels between classical and English literature, and consulted Alan about the probability and statistics necessary in such comparisons. He was also interested in the significance of astrology in the classics, and picked Alan’s brains for some elementary astronomy.

The real discussion
⁶¹
was recorded at the BBC Manchester studio on 10 January 1952. It was left to the brain surgeon to show the flag for the cause of consciousness, with Alan trying to haul it down. Max Newman and Richard Braithwaite, the King’s philosopher of science, acted as referees.

It was couched in the jocular-Mandarin style of the day. ‘Of course’, wrote Alan to his mother, who listened to the broadcast, ‘most of the questions put to me were more or less written in gags.’ Braithwaite began with a very appropriate
Brains’ Trust
point: ‘it all depends on what is to be included in thinking.’ Alan explained the imitation game as a criterion of ‘thinking’, the others duly chipping in to put the objections. ‘Would the questions have to be sums,’ asked Braithwaite, ‘or could I ask it what it had had for breakfast?’ ‘Oh yes, anything,’ said Alan, ‘and the questions don’t really have to be questions, any more than the questions in a law court are really questions. You know the sort of thing, “I put it to you that you are only pretending to be a man,” would be quite in order.’ They discussed
learning and teaching, and Braithwaite said that people’s ability to learn was determined by ‘appetites, desires, drives, instincts’ and that a learning machine would have to be equipped with ‘something corresponding to a set of appetites’.

Newman steered a course back to the safer waters of mathematics, pointing to the act of imagination that had been required to connect the ‘real numbers’ of length with the integers of counting, which involved ‘seeing analogies between things that had not been put together before. … Can we even guess at the way a machine could make such an invention from a programme composed by a man who had not the concept in his own mind?’ Alan
could
guess, in fact; it was just the kind of thing he was thinking about:

I think you could make a machine spot an analogy, in fact it’s quite a good instance of how a machine could be made to do some of those things that one usually regards as essentially a human monopoly. Suppose that someone was trying to explain the double negative to me, for instance, that if a thing isn’t not-green it must be green, and couldn’t quite get it across. He might say, ‘Well, it’s like crossing the road. You cross it, and then you cross it again, and you’re back where you started.’ This remark might just clinch it. This is one of the things one would like to work with machines, and I think it would be likely to happen with them. I imagine that the way analogy works in our brains is something like this. When two or more sets of ideas have the same pattern of logical connections, the brain may very likely economise parts by using some of them twice over, to remember the logical connections both in the one case and in the other. One must suppose that some part of my brain was used twice over in this way, once for the idea of double negation, and once for crossing the road, there and back; I am really supposed to know about both these things but can’t get what it is the man is driving at, so long as he is talking about all these dreary nots and not-nots. Somehow it doesn’t get through to the right part of the brain. But as soon as he says his piece about crossing the road it gets through to the right part, but by a different route. If there is some purely mechanical explanation of how this argument by analogy goes on in the brain, one could make a digital computer do the same.

Wittgenstein had talked about ‘explaining’ double negation in 1939.
⁶²
But Jefferson brought the discussion back to earth with the problem of appetites. ‘If we are really to get near to anything that can be truly called “thinking”, the effects of external stimuli cannot be missed out. … You see a machine has not [an] environment, and man is in constant relation to his environment, which as it were punches him whilst he punches back. … Man is essentially a chemical machine, he is much affected by hunger and fatigue … and by sexual urges.’ Alas, those appetites that interfered with thinking! It was a strong argument against the discrete state machine. But Jefferson again spoilt his case with an appeal to the complexity of the nervous system (irrelevant since a universal machine, given sufficient
storage, could emulate one of any complexity). In more rhetorical vein he continued, ‘Your machines have no genes, no pedigrees. Mendelian inheritance means nothing to wireless valves,’ and so forth. Jefferson wanted to say that he would not believe a computing machine could think until he saw it touch the leg of a lady computing machine, but they cut this out of the broadcast because (as Braithwaite said) one could hardly call that
thinking
. Braithwaite believed it would be necessary for the computer to incorporate an ‘emotional apparatus’ in order that it could think, but that it was not their concern to ask what problems this might lead to. The hot potato was dropped, and Jefferson concluded by reassuring the British intelligentsia that it was ‘that old slow coach, man’ who would continue to produce the ideas.

The broadcast went out on 14 January, by which time Arnold had made his second visit to Alan’s home, and events had taken a more serious turn. Alan had arranged matters so as to cast the relationship as an ‘affair’, which meant that Arnold had arrived as a dinner guest, and expected to stay the night. Arnold responded warmly to what was for him the palatial circumstances of Hollymeade, it being particularly striking, for instance, that Alan employed a housekeeper. He was with the masters now, not the servants.

They did not have much in common to talk about, but found links, in such a way that Arnold was highly conscious of Alan’s need to communicate and reach a fresh mind. Neither thought much of the American interference with the British attempt to oust Mossadeq in Iran. Arnold had great local patriotism and disliked the USAF bases still dominating parts of Cheshire. Besides current affairs Alan also talked about astronomy, played a tune on the violin, and let Arnold have a try. After dinner, rather the better for wine, and lying on the rug, Arnold began telling Alan about his recurrent childhood dream, or nightmare rather, in which he felt himself suspended in absolutely empty space while a strange noise would start, growing ever louder, until he woke up in a sweat. Alan asked what kind of noise it was, but Arnold could not describe it. Thinking of big empty spaces, Alan imagined the old hangar on the RAF camp along the road, and made up a science fiction story (he talked a bit about H.G. Wells) in which the hangar was itself a brain, programmed in such a way that it would work normally for anyone else, but when
he
went in to the hangar, he would be trapped. The doors would shut. And then he would have to play against the machine, a game of chess, the best out of three. The machine would counter his moves so quickly that he would have to make conversation to distract it. So he would talk to it, first making it show anger, then pleasing it by being stupid himself, and making it feel smug.

‘Can you
think
what I
feel?
Can you
feel
what I
think?’
, he said with terrific emphasis at one point, as he became more excited with the story. He quite transfixed Arnold as he took a piece of chalk, and imagined how he could beat the machine, by doing arithmetic so badly and slowly and stupidly that it would commit suicide in despair.

Arnold tried to explain
his ideas too; and Alan was patient, although he could so easily have been crushing, and led him on Socratically. ‘Whatever you think,
is,’
said Alan at one point, and this meant a lot to Arnold, who had his own dreams that he wanted to come true. Alan felt frustrated because he could not better communicate his ideas: ‘There’s got to be more to it than this level,’ he told Arnold, almost in anger, adding with great emphasis ‘I’ve got to
teach
you, take you out of all this.’

Dear love of comrades! – in 1891 Edward Carpenter had met his George Merrill, a working man of twenty; it began just like this, and continued for thirty years. Alan made it clear that he wanted them to sleep together as lovers, and this they did. In the morning Alan got up and made the breakfast, after which they talked and smoked and prolonged the pleasure of the night. They arranged for another visit in two weeks’ time. One subject was not, however, discussed as it might have been. This was the question of money. It was as obvious that Arnold was short of it as it was clear that Alan had more than he needed. Alan was going to do the expected thing, and was perhaps surprised when Arnold declined the offer. The underlying difficulty was that Arnold jibbed at a direct payment, which threatened to label him as ‘a renter’. Alan, in contrast, was highly uncomfortable about conventional social manoeuvres, whether in his mother’s drawing room or in his own bedroom. He was therefore particularly shaken next day to notice the absence of some money from his wallet, which he suspected that Arnold could have taken while he was making the breakfast. He wrote to Arnold, saying that he did not after all wish to continue the acquaintance. But Arnold arrived on his doorstep a few days later, demanding to know the reason for this rejection, and denying that he had anything to do with the loss. Alan was ‘half convinced’ by his indignation. Arnold went on to mention that as it happened he was £10 in debt for a suit bought on hire purchase, and asked to borrow £3. Alan gave him the money, saying that it was a gift, and later wrote to Arnold restoring the invitation. Arnold wrote back to thank him on the 18th, but added a request for a further £7 loan. Alan’s response was to ask for the name of the firm to which the money was owed: it was not the money but the truth of the story which was the issue for him. Again, on the 21st, Arnold arrived at Hollymeade to complain of the lack of trust that Alan showed, and left with a cheque for £7. He was going to start work in a Manchester printing shop, and so could promise to pay it back from his earnings.

Meanwhile Robin had come to stay for the weekend, which was devoted to a discussion of his essay on Eddington’s ‘Fundamental Theory’ of physics. This Alan said was ‘very much more satisfactory than anything you have done before.’ This stern praise meant a great deal to Robin, whose 1949 King’s fellowship dissertation had met with sharp criticism from Alan which had left him in tears.

Eddington had died in 1944 leaving unfinished an attempt to develop a
theory of physics from nothing but logical necessity. It was a somewhat Turingesque venture, and met with Alan’s sympathy in principle, but he had long since decided that Eddington was ‘an old muddle-head’ and wanted to see the ‘Fundamental Theory’ debunked. Robin, who never knew how important Eddington had been to Alan twenty years before, had found a number of errors in his arguments, including one which could be regarded as a confusion of logical types. It was a nice meeting of logic and physics.

Life went its ordinary way. Alan’s aunt Sybil had died on 6 January, and left him £500. The last survivor of his father’s generation, she had accumulated the Turing fortunes. She left £5000 to Mrs Turing, who for some reason had the idea of taking out a mortgage on her house, a policy which in a typical turn of phrase Alan called ‘about as appropriate as going out charring when you need more help in the house’. He stopped the £50 per annum he had sent her since 1949.

He had listened to the broadcast and found his voice ‘rather less trying to listen to than before’. On Wednesday 23 January, the programme was repeated. And the same day, the environment punched him back, as Jefferson put it. Alan arrived back in the evening to find that his house had been burgled. Alan was writing next day to Fred Clayton in connection with the astronomy of the ancient world. He explained the significance of the zodiac, and ended: