Alan Turing: The Enigma The Centenary Edition

by Andrew Hodges

  WITNESS: In a way.

  INTERROGATOR: Yet Christmas is a winter’s day, and I do not think Mr Pickwick would mind the comparison.

  WITNESS: I don’t think you’re serious. By a winter’s day one means a typical winter’s day, rather than a special one like Christmas.

  But this answer to the objection would prompt the same questions about the role of interaction with the world in ‘intelligence’. This play with words was the strawberries and cream, and not the meat, of literary criticism. It was a view of sonnets from the back of Ross’s English class! Where lay the ‘genuine feeling’? What Jefferson could well have intended, was something more like intellectual integrity than examination mark-scoring: truthfulness or sincerity pointing to some connection between the words, and experience of the world. But such integrity, a constancy and consistency in word and action, could not be enjoyed by the discrete state machine alone. The issue would be clearer if the machine were confronted with a question such as ‘Are you or have you ever been …’ or ‘What did you do in the war?’ Or staying with the sexual guessing game, asked to interpret some of the more ambiguous of Shakespeare’s sonnets. If asked to discuss proposed alterations to literature, Dr Bowdler’s preference for

  Under the greenwood tree

  Who loves to work with me

  would make a telling topic. Questions involving sex, society, politics or secrets would demonstrate how what it was possible for people to say might be limited not by puzzle-solving intelligence but by the restrictions on what might be done. Such questions, however, played no part in the discussion.

  Alan disliked anything with a churchy or pretentious flavour, and employed a light style with homely metaphors in order to make his serious points. It was in the Apostolic tradition, and also shared with Samuel Butler and Bernard Shaw. But rather like those writers, his examples of ‘intelligence’ could be accused of a touch of the blarney, of arguing for the sake of it, of mere cleverness, or of making debating points. He enjoyed the play of ideas – but a logical jousting with God and Gödel, the Lion and Unicorn tussle of free will and determinism, was not enough.

  It was not necessary to be either ‘soupy’ or pretentious in order to approach the questions of ‘thinking’ or ‘consciousness’ in another way. It was the year 1949 that saw Nineteen Eighty-Four – a book that Alan read, impressed: it elicited from him an unusually political comment when talking with Robin Gandy: ‘… I find it very depressing. … I suppose absolutely the only hope lies in those proles.’ Orwell’s discussion of the capacity of political structure to determine language, and language to determine thought, was itself highly relevant to Alan Turing’s thesis. And Orwell might have been thinking of the Turing sonnet-writing computer, with his ‘versificators’, machines to turn out popular songs.

  But that was not the central issue, for Orwell was not concerned to reserve for human beings the intelligent, indeed intellectually satisfying, work of rewriting history at the Ministry of Truth. His passion was reserved for intellectual integrity: keeping the mind whole, keeping it in contact with external reality. ‘You must get rid of those nineteenth-century ideas about the laws of Nature,’ O’Brien told Winston Smith, ‘We make the laws of nature. … Nothing exists except through human consciousness.’ Here lay Orwell’s fear, and to counter it he seized upon scientific truth as an external reality that political authority could not gainsay: ‘Freedom is the freedom to say two and two make four.’ He added in the unchangeable past, and sexual spontaneity, as things that were so, whatever anyone said. Science and sex! – they had been the two things that allowed Alan Turing to jump out of the social system in which he was trained. But the machine, the pure discrete state machine, could have none of this. Its universe would be a void, but for the word of its teacher. It might as well be told that space was five-dimensional, or even that two and two made five when Big Brother decreed. How could it ‘think for itself, as Alan Turing asked of it?

  As they might say on the Brains’ Trust, it all depended upon what was meant by ‘intelligence’. When Alan first began to use the word, it was applied to chess playing and other kinds of puzzle-solving. It was a sense which accorded well with the wartime and immediate post-war mood, in which intelligence was what Hut 8 had, and the Admiralty did not. But people had always used the word in a broader sense, involving some insight into reality, rather than the ability to achieve goals or solve puzzles or break ciphers. This discussion was missing from Computing Machinery and Intelligence. There was only his passing comment about Helen Keller to justify a claim that the means of communication, the interface between brain and world, would be irrelevant to the acquisition of intelligence. But this was a slight argument for so central a question. Even Bernard Shaw, in his irrational way, had put his finger on the problem that Alan ducked:

  PYGMALION. But they are conscious. I have taught them to talk and read; and now they tell lies. That is so very lifelike.

  MARTELLUS. Not at all. If they were alive they would tell the truth.

  Inevitably, Alan’s choice of emphasis reflected his background and experiences. As a mathematician, he was concerned with the symbolic world. And more than this, the formalist school of mathematics, which had given such a start to his career, had explicitly been concerned to treat mathematics as if it were a chess game, without asking for a connection with the world. That question was, as it were, always left for someone else to tackle. The game-like character of formalism showed itself in the present discussion, matching the Looking Glass quality of these ‘interrogations’. It might be said, in fact, that the kind of machine behaviour that he was describing, a behaviour unrelated to action, was not so much the ability to think as the ability to dream.

  The discrete state machine, communicating by teleprinter alone, was like an ideal for his own life, in which he would be left alone in a room of his own, to deal with the outside world solely by rational argument. It was the embodiment of a perfect J.S. Mill liberal, concentrating upon the free will and free speech of the individual. From this point of view, his model was a natural development of the argument for his definition of ‘computable’ that he had framed in 1936, the one in which the Turing machine was to emulate anything done by the individual mind, working on pieces of paper.

  On the other hand, he knew better than that, his strength lying in a seriousness directly applied to reality, rather than in ingenuity applied to puzzles. In 1938, his Ordinal Logics paper had carried the comment: ‘We are leaving out of account that most important faculty which distinguishes topics of interest from others; in fact, we are regarding the function of the mathematician as simply to determine the truth or falsity of propositions.’ He himself had carefully chosen topics of interest for the application of his mind; topics that mattered. This crucial faculty could find no room in the discrete state machine, depending as it did upon contact with reality. But more than this – he had to live in the world and communicate, like anyone else. And his fascination with computers had a complementary aspect, one of extreme consciousness of the social rules and conventions placed upon him. Puzzled since childhood by the ‘obvious duties’, he was doubly detached from the imitation game of social life, as pure scientist and as homosexual. Manners, committees, examinations, interrogations, German codes and fixed moral codes – they all threatened his freedom. Some he would accept, some actually enjoy obeying, others reject, but in any case he was peculiarly conscious, self-conscious, of things that other people accepted ‘without thinking’; It was in this spirit that he enjoyed writing formal ‘routines’ for the computer, just as he enjoyed Jane Austen and Trollope, the novelists of social duty and hierarchy. He enjoyed making life into a game, a pantomime. He had done his best to turn the Second World War into a game. Again, it was expressed in his other 1936 argument for computability, in which the Turing machine was to do anything conventional, anything for which the rules were laid down.*

  The free individual, sometimes working with the social machine, more often against it
, learning by ‘interference’ from outside, yet resenting that interference: the interplay between intelligence and duty; the abrasion and stimulation of interaction with the environment – this was his life. While all these elements were reflected in his ideas about machine intelligence, they were not all satisfactorily brought together. He had not tackled the question of the channels of communication, nor explored the physical embodiment of the mind within the social and political world. He had brushed these aside lightheartedly. He had not always done so, once writing to Mrs Morcom of how we could live free as spirits and communicate as such, ‘but there would be nothing whatever to do.’ Thinking and doing; the logical and the physical; it was the problem of his theory, and the problem of his life.

  In the summer of 1950 he decided to end his life of suitcases and landladies’ crockery. He bought a house in Wilmslow, the middle-class dormitory town in Cheshire, ten miles to the south of Manchester. It was a semi-detached Victorian house on a line of development that lay on the further side of the railway station, and which formed its own identity as the village of Dean Row. The fields and the hills of the Peak district lay immediately at the back. Here at least he was free. Neville thought he should not live alone, but he was no more alone by himself than he was amidst the madding crowd. Neville himself had finished his Cambridge statistics course and had managed to get a job with an electronics company near Reading, where he went to live with his mother. It was now much more difficult for them to meet, and this made another change in Alan’s life.

  The house, ‘Hollymeade’, was rather larger than he needed – a little selfish, perhaps, in the housing crisis of 1950. The quite good pieces of furniture that he acquired never overcame the sense of sparseness, and a somewhat temporary flavour. Certainly his ideas on how to live had little in common with his respectable neighbours – but there was one piece of good luck. His immediate neighbours, in the other half of the building, were the friendly Webbs. Roy Webb, as it happened, had been Alan’s almost exact contemporary at Sherborne, and was now a Manchester solicitor. They welcomed him for cups of tea and the occasional dinner; Alan used their telephone, never having one installed himself; they shared their gardens, the Webbs cultivating part of Alan’s patch. Alan offered gardening, along with chess and long-distance running, as his recreations in Who’s Who.41 But it was more pottering in the wilderness of nature than arranging the trim lawns of suburbia. ‘Things don’t grow in the winter,’ he told Roy Webb, explaining his laissez faire attitude to the vegetable world. The Webbs grew used to seeing him at any time in vest and shorts, and they also had him baby-sit for their son Rob, who had been born in 1948. Alan enjoyed this; it would have been of intellectual interest to him to see a brain awakening into conscious speech, but it was also a simple delight in communication that the little boy reciprocated. Later on they would sit together on the Webbs’ garage roof, and were once heard discussing subversively whether, if God sat on the ground, He would catch cold.

  Having his own home gave him more opportunities to play the desert island game, of using his ingenuity to make things he needed for himself. He wanted a brick path, and at first wanted to fire the bricks himself, like the chess set at Bletchley, but settled for ordering a load. He did the laying himself, but found he had grossly underestimated the cost, and for this reason the path was never finished. As in the war, stories like this helped people to cope with his more forbidding aspects, and as in the war, his messy, spartan environment was far more striking to those unfamiliar with Cambridge dons. It also upset those who supposed a middle-class man incapable of doing anything with his hands.

  Alan did not, however, achieve a self-sufficient existence: he cheated by having a Mrs C—to shop and clean for him on four afternoons a week. Indeed he could be seen as hankering after having someone to look after him, and to give him the home comforts that he was unwilling, or unable, to provide for himself. He would have liked the convenience, but not the fuss and interference, of domestic life. The ordinary life of the Webbs next door gave him some contact with what he missed in this respect. But he did learn to cook for himself, so that Mrs Webb found herself not only explaining how to dry socks, but giving all the details on how to make a sponge cake. Alan enjoyed showing off to visitors a new skill, remote from his education but close to his own experiments as a little boy.

  Not many visitors trudged a mile along the road from the station past the RAF camp. Sometimes junior engineers were invited down, and might collect some apples; Bob and his wife came over once or twice, before he went to work abroad. Robin Gandy was a regular visitor, for at least once every term he would come for a weekend from Leicester where since October 1949 he had been a lecturer at the University College. Alan had by now become his PhD supervisor. They would mainly discuss the philosophy of science, though Robin’s interest was turning more and more towards mathematical logic itself, rather than the logic of science, and his work was meeting up with Alan’s. In fact like the White Knight, who was interested in songs, and the names of songs, and the names of the names of songs, Robin had become primarily interested in the theory of types, reviving Alan’s interest in the subject. They might also do a few jobs in the house or the garden together, and afterwards there would always be a bottle of wine with the dinner – which Alan would mull by plunging it in a jug of very hot water. That was an invariable rule, and another was to put the cork back in the bottle after the meal was finished, even if Robin would have preferred to finish it off. After the meal, as they did the washing-up, there would be some exercise to perform, such as working out how it could be that trees drew water up more than thirty feet.

  There might well have been another kind of occasional visitor to his life, if not to his house, one that came through the trade entrance. For all the time there was another England, on towpaths or trains, in pubs, parks, toilets, museums, at swimming baths, bus stations, shop windows, or just looking back in the street, for those who had eyes to see; a communication network of flashing eyes, millions and millions of them, sundered from the lobotomised culture of official Britain, but to which Alan Turing belonged. Before the war he would have been too shy, but by 1950 he had made some discoveries. Traditionally, for the upper-middle-class homosexual man, there was Paris, and going abroad was a double escape, both from the English law, and from the class system which enveloped an Englishman as soon as he opened his mouth. But England had its opportunities too. Alan always used to stay in the YMCA in London, if only because it would hardly occur to him to pay to stay anywhere grander, and this would have held something for his eye in the shape of naked youths in its swimming pool, if nothing more. But Manchester was another story.

  Walking up to the city centre from the Victoria University, there was a point where Oxford Road became Oxford Street, just under the railway bridge. Here it was a long way indeed from the dreaming spires at the other end of the A34. There were a couple of cinemas, an amusement arcade, a pub – the Union Tavern – and a very early example of the milk bar. This stretch between the urinal and the cinema was where the male homosexual eye was focussed – perhaps the same block as trodden by Ludwig Wittgenstein in 1908, such unofficial institutions lasting as long as the respectable kind. Here straggled a motley convoy of souls, and amidst them the odd independent sailing, like Alan Turing. Here merged many kinds of desire – for physical excitement, for attention, for a life outside family and factory confines, or for money. These were not sharp divisions. Money, if involved, was little but the clink of ‘tipping’ that was heard in any encounter between different social classes; and indeed little different from the way that women could expect to be entertained and treated by men. The most special relationship would have its quid pro quo, and this kind was more likely for ten bob than a quid. This was how it was done in the ordinary England of 1950, outside privileged circles such as those of Cambridge or Oxford. For the young, in particular, without means or private space, homosexual desire meant street life. Desert island sex, managing on the minimum of soc
ial resources, and only noticed when something went wrong, this was not for the respectable man. But Alan was above respectability.

  Candide had retired to cultiver son jardin, the back garden of science. But what was his ‘programme for the immediate future’? The past two years had offered flashbacks to the successes of his earlier life. The usual academic course would be to build upon those successes, extracting as much as possible from them. But this was not his path; he had to find something new in order to continue. And he now began to draw upon something that had, in fact, been there all the time, but which only now began to emerge into light. It was as though a long sub-routine, that had begun with Christopher Morcom, passing through Eddington and von Neumann, Hilbert and Gödel, Computable Numbers, his war machines and mechanical processes, the relays and the electronics and the ACE, the programming of computers and the groping towards intelligent machinery – all that stream of enquiry had tapered off, and left him free to continue from where schooling had interrupted him.

  Already there had been a hint in Intelligent Machinery, for Sir Charles Darwin’s benefit:

  The picture of the cortex as an unorganised machine is very satisfactory from the point of view of evolution and genetics. It clearly would not require any very complex system of genes to produce something like the … unorganised machine. In fact this should be much easier than the production of such things as the respiratory centre. …

  Somehow the brain did it, and somehow brains came into being every day without all the fuss and bother of the minnow-brained ACE. There were two possibilities: either a brain learnt to think by dint of interaction with the world, or else it had something written in it at birth – which must be programmed, in a looser sense, by the genes. Brains were too complicated to consider at first. But how did anything know how to grow? There lay the question – a question that the smallest child could ask, and the question that Natural Wonders Every Child Should Know had placed at the centre. When embarking upon the delicate subject of ‘what little boys and girls are really made of’, E.T. Brewster had launched into a description of the growth of starfish, beginning with the young egg, before there is any sign of a growing creature inside. One would perhaps expect to see the oil and jelly mixture change gradually into a star-fish. Instead of this, however, this little balloon-like affair splits squarely into two, and makes two little balloons just alike, and which lie side by side. … In about half an hour, each of these balloons or bubbles, ‘cells’ as they have come to be called, has divided again; so that now there are four. The four soon become eight; the eight, sixteen. In the course of a few hours, there are hundreds, all sticking together and all very minute; so that the whole mass looks like the heap of soap bubbles which one blows by putting the pipe under the surface of the soap suds.