Alan Turing: The Enigma The Centenary Edition

by Andrew Hodges

  men shall learn to accept one another simply and without complaint …honour the free immeasurable gift of their own personality, delight in it and bask in it without false shames and affectations.

  and he was pleased that Alan had chosen to tell him. It was very different from the sticky moment with Don Bayley. Robin was rather surprised that Alan was so forthright, for if obliged to give an opinion at Hanslope, he would have said that Alan did seem to be more drawn towards men, but that he was probably too shy and inhibited to do anything about it. The truth made Alan less austere and more fun. Alan in turn was very pleased that Robin should understand him so well, and with that out of the way, there was nothing (except Bletchley Park) that they could not talk about, whether of science or gossip.

  He was altogether more confident with people than he had been before the war, and was elected to George Rylands’ play-reading Ten Club, which he would have found frighteningly precious and pretentious then. He was not elected to the Apostles. Robin was an Apostle, and would have proposed him, except that at that point they were choosing only rather younger candidates. He did, however, become rather better connected with the King’s social network, and Robin was particularly helpful in opening up his life to more communication, compensating for some of the fraught years of silent, frustrated desire. ‘When I recall some past epoch,’ Alan said in reply to some question about the past from Norman Routledge, a new acquaintance of this year, ‘I think of whoever I was in love with at the time.’

  The winter was spent on various topics, none with all-absorbing attention. The numerical analysis paper47 – the only published evidence of his ACE work – was finished in November. Most of all he wanted to understand more about ‘thinking’. Somehow the brain did it – but how? Contemporary physiologists had only the faintest ideas about neural stimuli and responses. He went to R.H. Adrian’s lectures, but was disappointed. Chemistry and physics were at last pushing their way into biology, but his whole thesis lay in a different kind of description, the logical description of the nervous system, for which chemistry and physics were only the medium. He conveyed his disappointment to Peter Matthews, a very sharp undergraduate, one of the few who had come to Cambridge at eighteen, with whom he went to the physiology lectures. They would talk long over lunch and over mugs of cocoa in the evenings, since they lived on the same staircase.

  Jim Wilkinson would visit Cambridge from time to time, and kept Alan informed as to the developments, or lack of them, back at Teddington. The news was that of cuts, crises, and an ever-narrowing vision. At a meeting in November, they had abandoned many of the advanced ideas for the ACE, including the ‘abbreviated code instructions’. An edict from Darwin had stopped Huskey’s Test Assembly, because of complaints from Thomas. The ACE section was reduced to the writing of a report48 on their numerical analysis and programming work.

  In the new year of 1948, an alternative possibility came into being for Alan’s future. For if the NPL project had ground to a sticky halt, the Manchester development had bounded along with great speed. By the end of 1947 Williams had stored 2048 digits on an ordinary cathode ray tube screen, which was at least the equivalent of having a cheap, working delay line available. Newman still had his Royal Society grant virtually intact, and mooted the idea that Alan should take an appointment at Manchester to direct the computer construction there instead. Alan did not decide immediately, but in March Newman asked his university49 to create a new position, with a salary paid from the computer fund, but with the status of Reader.*

  The prospect of getting his hands on a computer after all was very attractive. But so was life at Cambridge, the nearest he had to a home. He joined the Moral Science Club again, and gave them a talk50 on ‘Problems of Robots’ on 22 January. (That Czech word ‘robot’ had a topical flavour.) He joined the Hare and Hounds Club, and continued his training, often running to Ely and back in the afternoon. He tried some von Neumann game theory, and rather laboriously worked out a strategy for a simplified version of poker, slightly improving upon the account given by von Neumann,51 and also for the Princeton game of Psychology. Robin was moving away from theoretical physics and into the philosophy of physics, and there were many discussions with him and his friend Keith Roberts. Once they had tried to set up a purely operational definition of Special Relativity, and when one of them objected that there was no such thing as a rigid body in relativity, Alan said, ‘Well, let’s call them squeegees’ It was that pleasant, unpompous way of being serious without being solemn that in 1948 was far from widespread in academic life, and was associated with the legacy of the Apostles and the King’s milieu – though it came naturally to Alan. There was another nice occasion when Don Bayley came for the weekend to see Alan and Robin, to be greeted with a toy steam engine that Alan had bought at Woolworths. ‘I always lusted after things like this as a boy,’ he said ruefully, ‘but didn’t have enough pocket money for them. Now I have got enough money, I might as well have it.’ They played with it for the afternoon.

  Alan had told Robin that ‘Sometimes you’re sitting talking to someone and you know that in three quarters of an hour you will either be having a marvellous night or you will be kicked out of the room.’ It was not always like that, for the innocent Peter Matthews’ cocoa sessions did not involve this stark dichotomy. Nor was Alan accomplished in the necessary social game of words and eye-contact; he was too shy and brusque and lacking in confidence in his looks. Cambridge did inspire him with greater interest in his appearance, and sometimes he would show Robin a photograph of himself at sixteen and say how handsome he looked then. He was certainly not attractive in the Aryan-Brylcreem style of the 1940s. To the fastidious, his open-necked, shabby, breathless immediacy came as messy and coarse, though there were redeeming features; he could put on a roguish charm which reminded people of his Irish ancestry, and besides his piercing blue eyes he had thick, luxuriant eyelashes and a soft-contoured nose. But whatever his doubts and disadvantages he would pace round the courts of King’s and invite young men in for tea. Sometimes he struck lucky. In April 1948 he struck very lucky indeed, for Neville Johnson stayed for tea, and stayed many times.

  Neville was a third-year mathematics student, then twenty-four, but mathematics was not a cement but an embarrassment in their relationship, for although Neville had won a scholarship, this was ‘a flash in the pan’. It made Neville feel inferior that they were in this respect on quite different planes. Once Alan said, ‘When you know what the Entscheidungs problem is, you will know what a great mathematician I am,’ with a sad twinkle, but Neville never did find out. Neville thought he was very ordinary compared with the more glamorous side of King’s, and that he was just ‘the best that Alan could get’.

  But for Alan, it was probably an attraction that Neville, a Geordie from Sunderland Grammar School and the Army, was someone down to earth and rather tough. His problem lay far more in having to remove the anaesthetising shell with which he had protected himself for so long. Perhaps it was too late. To Neville, it seemed that Alan had enjoyed ill luck with people, and that it was not surprising that he was keen on machines to replace them. Once he said to Neville, lying on his bed, ‘I have more contact with this bed, than with other people.’ He also unburied a little of the past. Christopher still prodded him, if only because he would faint at the mention of blood or dissections in the physiology lectures; but in 1948 he was ‘A very upper-class boy, from where they dressed for dinner.’ Of Bletchley he revealed that the Poles had brought something crucial – but that he must not say more. Once he pointed out a professor of Greek in the street and said he had done something marvellous there.

  They were often together, and sometimes with Alan’s friends, although Neville then felt rather out of place. Neville joined in the game of poker that they determinedly played in order to test out Alan’s minimax strategy. (It was not very exciting, as the strategy was largely the obvious one anyway.) It was another ordinary affair, at last, as it had been with James Atkins in the pre
-war days.

  This solved one problem. In other ways, Alan was back to the difficulties of 1939. For his mind still straddled mathematics, engineering and philosophy in a way that the academic structure could not accommodate. Temporarily the war had resolved his frustration, giving him something to do that was intellectually satisfying, yet which actually worked. But that was over now, and instead of being drawn in, he was being pushed out.

  How was he to continue, having won the war, and lost the peace? If he did not return to the NPL then the Entscheidungs problem lay between Cambridge and Manchester. He could stay at King’s, and a lectureship ought to come his way. He could return to the world of Hilbert and Hardy, as though the last nine years had never been. Yet no more than in 1939, was that the way his spirit moved. He did not want to go backwards, and he still wanted to grasp the computer that he had invented. At Cambridge, the computer was firmly in the grasp of M. V. Wilkes, and Alan was far, far too proud to go cap in hand to use it. If he wanted a computer, it meant going to Manchester.

  Darwin, meanwhile, expected him back at the NPL at the end of the Cambridge term. On 20 April 1948 he reported to the Executive Committee on ‘Future Plans for Dr Turing’:

  Dr Turing, who is on a year’s leave of absence at Cambridge University, will shortly be due to return to the laboratory and Director is proposing to discuss with him what type of work he should then undertake. Director felt that from the point of view of Dr Turing’s career, it would be an advantage if he started to write some papers rather than continue with the fundamental physiological studies into which his researches are carrying him. Dr Turing will no doubt join a University staff in due course, but Director felt that intervening period should be spent at NPL.

  Kind though it was of Darwin to think of his career, the fact was that the year’s wait had achieved nothing. Womersley reported to the same meeting that

  The present position on this project gives no cause for complacency and we were probably as far advanced 18 months ago. …There are several competitors to the ace machine, and of these, that under construction at Cambridge University, under Professor [sic] Wilkes, will probably be the first in operation.

  Coordination and cooperation had long since been replaced by competition. A few days later Womersley reported52 to Darwin with proposals for the building of the machine, which he held to be ‘of supreme importance …in the fields of scientific research, administration, and national defence’. The proposals included ‘using as much of Wilkes’ development work as is consistent with our own programming system’, and making an approach to F.C. Williams to request a copy of the machine being built at Manchester. In this radical modification, or rather abandonment, of the ACE programme, no attention was paid to the ideas of its originator. The administrators appeared to regard him as an abstract, almost anonymous entity.

  Alan was not perhaps entirely free from responsibility for this absence of communication. It was, for instance, rude of him to postpone for a long time a visit to Wilkes at the Mathematical Laboratory in Cambridge – a short walk from King’s across Market Square, but not an easy one. As the time for decision approached, Alan said, ‘I really must go and see Wilkes’, and then put it off, and put it off again until the last minute in late May. By that time the construction of what was to be the EDSAC was in full swing. They were using mercury delay lines, and by good fortune, Gold had moved to Cambridge as a research student and supplied Wilkes with the designs. Instead of trying to work it all out by himself, Wilkes kept ‘religiously’ to Gold’s specifications and got on with building them. He had obtained money from the DSIR, the University Grants Committee, and from J. Lyons and Co. Ltd., reflecting a very early interest on the part of private enterprise. He was in full control, without a Womersley or a Darwin to get in the way, and working much as Alan would have liked to. The barricade between mathematics and engineering never arose. It was enough to show the folly of NPL policy, and jealousy would have been a very natural reaction. Afterwards he meanly said, ‘I couldn’t listen to a word he said. I was just thinking, how exactly like a beetle he looked.’ But duty was done.

  A few days later, on 28 May, Alan called in at the NPL. It was the sports day. He conferred with Jim Wilkinson, who explained the whole dismal story. Darwin might well have liked a series of papers going out under the NPL imprimatur, but Jim Wilkinson agreed that there was nothing in it for Alan. He also thought Alan should stay at Cambridge and return to pure mathematics. He foresaw problems at Manchester.

  Manchester University had indeed agreed to create a position for him, and on 21 May the Royal Society agreed that the salary could be paid out of their grant to Newman. A letter of 26 May, which Alan presumably received just before his NPL visit, informed him of this. It was on 28 May that he wrote accepting the appointment, and resigned from the NPL. It was against the ‘gentleman’s agreement’ of the sabbatical, according to which he was supposed to stay for another two years. He had broken an engagement for a second time. Darwin was extremely annoyed with Blackett and Newman. Humpty Dumpty had had a great fall.

  Everyone had been slow to adjust to the realities of the post-war period. In expecting the Post Office to cooperate on the delay lines, Alan had been as unrealistic as any of the administrators. And yet it was still extraordinary that as late as May 1948 there was no sign of any start being made on the construction of the control circuits. This failure could not be laid at Alan’s door: to see that plans were implemented was the job, and indeed the only raison d’être, of the administrators. But perhaps Darwin never really wanted a computer, just as the Admiralty had not really wanted to know where German ships were. The ‘support’ of Travis and the Ministry of Supply had not in fact made any difference to the bureaucratic inertia. Darwin and Womersley had played at being commissars while Alan remained the humbler worker and peasant.

  If he had been given his head, the project might well have gone adrift. He probably underestimated the technical difficulty of running pulses at the rate of a million a second, and overestimated his own engineering knowledge. He would have interfered in too much detail, annoying people who would not like being lectured on their own jobs. He would have had no idea of how to pull off a deal for the right equipment, how to flatter someone into doing the job the way he wanted, or how to play off one expert against another. He had no management skills. But he was not given a chance to make a mess of it for himself, as was his right as the creative worker. And basically his approach was on the right lines, for in the end every successful computer project had to solve the problem of integrating ‘mathematical’ and ‘engineering’ skills, which was exactly what he longed to do.

  The war had given him a false sense of what was possible. For him, breaking the Enigma was much easier than the problem of dealing with other people, especially with those holding power. During the war his own kind of work had been amplified into something enormously real, but only because other people had done all the work of organising coordination, and because he had Churchill’s personal backing. Now there was nobody to do this for him, the NPL administrators not really having tried. A different person could more easily have compromised, and more effectively have fought on for the success of the project. But with him, it was all or nothing. Like his father, he had resigned from the Civil Service when the system did not work for him. Unlike his father, however, he did not moan afterwards. Indeed, he very rarely referred to his time at the NPL. It became another great blank, to add to all the others.

  Despite his resignation, and all the embarrassment that surrounded it, he completed a report53 for the NPL in July and August 1948. Its almost conversational style reflected the discussions he had pursued, many at Bletchley, in advancing the idea of Intelligent Machinery. Although nominally the work of his sabbatical year, and written for a hard-line technical establishment, it was really a description of the dream of Bletchley Park, and reviewed in an almost nostalgic way the course of his own life rather than contributing to any practical proposals that the
NPL might adopt.

  Expanding upon the ideas he had publicly announced in February 1947, this time he identified some of the reasons why the concept of ‘intelligent machinery’ might be perceived by such as Darwin as a contradiction in terms:

  (a) An unwillingness to admit the possibility that mankind can have any rivals in intellectual power. This occurs as much amongst intellectual people as amongst others: they have more to lose. Those who admit the possibility all agree that its realisation would be very disagreeable. The same situation arises in connection with the possibility of our being superseded by some other animal species. This is almost as disagreeable and its theoretical possibility is indisputable.

  (b) A religious belief that any attempt to construct such machine is a sort of Promethean irreverence.

  These objections, he wrote, ‘being purely emotional, do not really need to be refuted.’ They were like Bernard Shaw’s complaint against the first Charles Darwin, that his doctrines were ‘discouraging’. The point, however, was not to find comfort, but truth.

  He next moved to what he considered a less ‘emotional’, but still erroneous objection:

  (c) The very limited character of the machinery which has been used until recent times (e.g. up to 1940). This encouraged the belief that machinery was necessarily limited to extremely straightforward, possibly even to repetitive, jobs. This attitude is very well expressed by Dorothy Sayers (The Mind of the Maker, p. 46) .. which imagines that God, having created his Universe, has now screwed the cap on His pen, put His feet on the mantelpiece and left the work to get on with itself.’

  This, to Dorothy Sayers, made a reductio ad absurdum of determinism. How could Lord Peter Wimsey have been laid up for all time in the motions of the particles at the Creation? To Alan all it showed was that there was no word that expressed the ‘mechanical’ operations of machines with more than trivial logical structure. Dorothy Sayers did not know in 1941 that even the little Enigma machine was sufficiently unpredictable to keep hundreds of people in employment. He was certainly fascinated by the fact that a machine like the Delilah key generator could be perfectly deterministic at one level, while producing something apparently ‘random’ at another. It gave him a model for reconciling determination and free-will. But this did not go very far. It was the capacity of machines to learn that he saw as the crux of the argument. A learning machine would part company altogether with the ‘mere machine’ of common parlance.