For a figure in world history, there is very little source material from which to reconstruct a picture of Alan Turing – few original documents, and little in the way of published commentary. Secrecy and embarrassment of various kinds are partly responsible, but there is a paucity of information even where taboo subjects are not involved. The early development of the ACE, for instance, is covered incompletely by the surviving records – and some of the most interesting exist only thanks to unofficial individual initiative. The ACE represented a major act of public enterprise, and the events of 1946-9 largely determined the shape taken in Britain by what was soon to be seen as a second industrial revolution. Had cooperation between government, industry and brain power been continued in peace as in war, the future of the British economy might have been very different. But no special effort was made to record the course of decisions made, nor has the subject subsequently attracted the interest of historians or journalists or political theorists. And what is true of the ACE as a whole is even more true of Alan Turing’s personal part.
One must recognise, however, that Alan Turing did not conduct his life as that of a figure in world history: he tried as best he could to continue the life of an ordinary mathematician. And mathematicians (as compared with literary or political figures, entertainers or spies) do not usually expect to be heard of or written about, whatever their contribution. They do not really expect other people to know what mathematics is, and are generally happy to be left alone. When judged by mathematical standards, one could not say that for a figure of his stature there has been any particular deficiency in records or neglect in reputation.* Pathetically small by worldly standards, the corpus of biographical material is still substantial in comparison with that of others in his profession.
Taking first the question of what was written of him after his death, over the next twenty years or so, there were of course obituaries: Max Newman in The Times, Robin Gandy in Nature, Philip Hall in the King’s College Annual Report, and various more minor tributes. Newman followed by writing the Biographical Memoir to which Alan, as a Fellow of the Royal Society, was entitled. One of the fuller and more penetrating of the series, it treated his life and work from the point of view of a pure mathematician. The Second World War thus appeared as an interruption to his work on logic and the theory of numbers. The subject of his war work had to go unmentioned but so, with ruthless consistency, was the subject of practical computers relegated to a few lines. This analysis embodied the outlook of an intellectual tradition to which Alan Turing had certainly half-belonged, but it was not the whole story.
One person was not satisfied with this assessment, and sensed that some other kind of recognition was due. This Was Mrs Turing, who in 1956 embarked upon writing a biography of her son – an extraordinary development by any standards, in which a seventy-five-year-old Guildford lady, not hitherto notable for literary or social confidence, and knowing almost nothing about science, was left to piece together some of the debris from the wreck of the modern world’s dream. Her Victorian values still unshaken, she retained a strong belief in the idea that Alan’s work had been and would be for the benefit of humanity.
Her slim volume appeared in 1959. There was perhaps a better book in Sara Turing, one that would have been a genuine memoir which placed the death alongside the other mysteries (as they were to her) of what her son had spent his life doing: something that could have pointed tellingly to the twentieth century separation of science from ordinary life, and to the efforts both he and she had made to overcome that separation – though not succeeding. But this was not what she did: her book was in the form of a biography and written with an apparent emotional detachment which was in itself remarkable, considering the frightful circumstances which had inspired it.
One reason that Alan’s mother could cast herself as a detached observer was that in so many ways she was writing about a stranger. The reader was not to know, but there was very little in her narrative of his early life – and the period up to 1931 absorbed a third of her account – which did not come from surviving letters and school reports. She was surely trying to prolong in her mind the lately increased rapport with her son, by projecting it back into a past life of which she knew little – not an inkling, for instance, of Christopher Morcom’s significance for her son’s development. The objective stance then obliged her to set out his scientific career – another impossibility. Alan had once compared the work of writing programs to imitate intelligent behaviour as like being set to write an account of ‘family life on Mars’. Mrs Turing had set herself a task of nearly equal diffficulty; rather as a computer might be programmed to write sentences of grammatical form, she was able to make a jigsaw of the titles of his papers, bits cribbed from the extant obituaries, comments solicited from other people, and newspaper cuttings. Yet she had little conception of what it meant.*
Her position of weakness was accentuated by an extraordinarily obsequious attitude to anyone of rank or office, which meant that by implication she put her son at the level of a promising sixth-former. Indeed her whole book read much like a school report. The flow of tributes bore witness to the fact that she was still having to convince herself that he had turned out satisfactorily after all, and indeed to her astonishment that there was a world in which he had actually been admired. Undercutting him again and again, Computable Numbers was good because Scholz had been impressed by it, his interest in the brain was significant because Wiener and Jefferson approved. … Alan might have seen this assessment as a fate worse than death, although it was partly the outcome of his own failure to promote himself.
Yet there was one point his mother grasped that better informed people could be too sophisticated to see, namely that in 1945 he had set out to build a computer. She stuck to this at a time when everything surrounding the subject was still suffused in embarrassment. And more generally, she displayed an amazing tenacity and nerve in tackling the male institutions from which she was excluded, and in refusing to be daunted by the polite evasiveness that she met. For of course there were two areas that were out of bounds – what he had done in the war and his homosexuality. A number of people felt they could not contribute anything whatever with honesty unless the unmentionable were mentioned – and of course it was not mentioned, no more than in any of the other written pieces. With the war she got a little further, being allowed to say that ‘he was one of a team whose joint work was an important factor in our winning the war’ – a hint which was as strong as anything that appeared in the next ten years.† Tiptoeing among the minefields – and perhaps anyone but her would have found it impossible to continue – she did, ultimately, stand up for him as few others would.
What was sad was not that she failed to do what was manifestly beyond her powers; it was that although she had her own insights and stories they did not, in fact, add up to an understanding or even a formulation of the particular enigma that Alan had posed for her. At the end she closed with a comparison of what she had written with the Lives of the Saints – Alan would have derided this attempt to get him through the eye of the needle, and yet had she pursued with any seriousness the subtle conflict of the ‘pure’ and the ‘applied’ she could quite legitimately have expressed it in religious language and found something quite special to say. But here she offered nothing: for examination marks, government service, and the building of machines appeared alike as undifferentiated Good Things. The absence of any question mark around the place of science was perhaps one reason why her book, pitiful by the standards that would be expected of a literary or political biography, attracted the gentle praise of critics. It was a holiday for a world trying to forget Dr Strangelove. At last, it seemed, here was a scientist untouched by the traumas of the 1940s and 1950s! There was a half-truth in this notion, there being something of the 1880s in Alan Turing as well as in his mother; but again it was hardly the whole story.
During the 1960s, and into the 1970s, Newman and Sara Turing were the sources upon which various encyclopedia entries, potted biographies and popular articles drew. But by the turn of the decade there were small sprouts of a different kind of comment pushing their way through the Stoney ground. One factor was simply the expansion and greater sophistication of what had become ‘computer science’, slightly modifying the status of computers as altogether infra dig. for a mathematician. It was in 1969 that Donald Michie published the NPL report Intelligent Machinery, he himself being concerned to set a lead in British developments. He commented in this period on how the prevailing attitude was that ideas about machine intelligence were a diversion from serious work; but the 1970s ushered in a greater appreciation of the computer as a universal machine, concerned with any and every form of logical manipulation, and not necessarily at work on arithmetical calculations. This general development encouraged a clearer understanding of what Alan Turing had envisaged from the beginning.*
It was also in 1969, as the computer came of age, that it was first noted, in articles by Mike Woodger and R. Malik, that Alan Turing had emerged from the war with a practical knowledge of electronics. This fact, quite at odds with the prevailing stereotype of ‘the logician’, as he appeared in H.H. Goldstine’s standard academic account of The Computer from Pascal to von Neumann in 1972, took some time to be assimilated; so likewise did the place of the ACE in computer history. The compilation by B. Randell of classic papers documenting the origins of digital computers (see note 5.23) relegated mention of the ACE to its bibliography, but the mini-boom of computer history did not entirely pass it by: in 1972 the original report was issued by the NPL, and it received a first serious review in 1975.
Meanwhile the turn of the decade had also seen the purpose of Bletchley Park become mentionable, although the first outright claim for its strategic significance came only in 1974 with F.W. Winterbotham’s The Ultra Secret. This book made no mention of Alan Turing, but in the same year A. Cave Brown’s imaginative work Bodyguard of Lies contained many sentences in which the word ‘Turing’ appeared, sometimes in conjunction with words such as ‘machine’ and ‘Bombe’. The floodgates were opened. Meanwhile Jack Good and Donald Michie had published certain disclosures concerning the electronic machinery at Bletchley. Drawing these developments together, the inquiries of B. Randell, motivated partly by the question of understanding Alan Turing’s part in the origin of the computer, enjoyed some success. His revelations of the Colossus technology did in fact reflect the achievement of Newman and Flowers rather than anything directly attributable to Alan Turing, but it meant that a first serious glimpse of the gigantic scale of operations had been given. Much of this, together with other mid-1970s disclosures, was brought together in a BBC television programme, one of a series on The Secret War, broadcast early in 1977.
Since 1969 was also the year of gay liberation, it meant that another change in how it was possible to think about Alan Turing occurred during the 1970s. This was not the result of the Wolfenden reforms – which, although delayed through the strenuous efforts of Viscount Montgomery and others, had passed into law as the Sexual Offences Act in 1967. Setting an ‘age of consent’ at twenty-one, this rationalisation and modernisation of the law ensured that the Turing crime remained a crime.* It was rather the brief renaissance of American liberalism that permitted a reversal of the concept of ‘problem’: seeing society as a problem for the individual rather than vice versa. In its way this development created the conditions for a rediscovery of Alan Turing’s life as much as did the other openings of the new decade: not just in that it was possible to say he was a homosexual, but in appreciating his pride, his stubbornness, and the moral force he brought to bear as a very private, reserved, shy man who nonetheless insisted that this was not a matter for hiding.
Taking these developments together, the 1970s therefore made it possible for someone to see who Alan Turing was, in a way that no one in his lifetime (but he himself) could have done. It so happened that I was placed in such a position as to be struck by all these developments. The name of Alan Turing first impinged on me in the summer of 1968 – essentially a reflection of the burgeoning of computer science, for I was reading about cybernetics and Turing machines as a mathematics student. In fact I did not choose to work in this field, moving instead into mathematical physics, learning about relativity and quantum mechanics from Roger Penrose as a postgraduate student from 1972 onwards, and trying to make a contribution to the Penrose theory of twistors.*
But in 1973 the name of Alan Turing impressed itself on me again, this time through another compartment of my life. I was then a member of a group that had formed within the London Gay Liberation Front to write a pamphlet criticising the medical model of homosexuality. One of the other members, David Hutter, had heard something of the end of the Turing story from Nick Furbank. Knowing nothing of his secret work, and believing that his death could be accounted for by the effect on his work of the hormone treatment, we included a paragraph which used this idea to illustrate our theme. Thus after twenty years there was a first public squeak of protest.
Lurking for years at the back of my mind, with a sense that I ought to have found out more about what happened, this story suddenly leapt to the fore again on 10 February 1977. On that day, while having lunch with Roger Penrose’s research group at Oxford, there was a conversation about the famous Mind article which took me back to my earlier interest in Turing ideas – and then quite independently, another about the BBC programme on Bletchley Park, which had been broadcast the previous evening. Roger Penrose commented on its fleeting mention of Alan Turing; he had long since heard talk of him as a man ‘hounded to his death’ but just recently there had been rumours of a man who had ‘deserved an earldom’. Nothing was clear or connected, and it was to be three years before I could compose a coherent interpretation of what had happened – but it was enough for me to sense
A war O soldiers not for itself alone,
Far, far more stood silently waiting
behind, now to advance in this book.
It had to be done, and it was the right moment to start. A first step was that of collecting extant publications, much as described above. But of course it was necessary to get much closer to my subject. So I turn now to the question of original Turing papers, where my first acknowledgement of a debt must be to Mrs Turing. According to her own book she once told Alan that she was putting things by for the use of a future biographer, and he grunted a gruff assent. Certainly she took the trouble to keep letters from her son’s schooldays onwards, used them for her book, and then in 1960 deposited them as a small archive in the library of King’s College, Cambridge.* She added to these seventy-seven letters a number of ancillary items, such as certain of the correspondence that arose in writing her book. A few other items went to Sherborne School.
Mrs Turing died at the age of ninety-four on 6 March 1976, and so never knew of me, nor indeed of what her son had done for the battle of the Atlantic. Before she died, however, she endowed an A.M. Turing Trust, to be chaired by Donald Michie, by then Professor of Machine Intelligence at Edinburgh University. It so happened that in 1977, just as I was first making enquiries, the Trustees had arranged for the deposit of all the surviving Turing papers in the King’s College archive. These papers had been kept since 1954 by Robin Gandy, himself now a distinguished mathematical logician at Oxford; but in 1977 they were being sorted and catalogued by Jeannine Alton of the Contemporary Scientific Archive Centre, also at Oxford. That these Turing trails had focussed on Oxford was coincidental, but helpful in my early efforts to grasp my subject. I should like at this point to record particular thanks to Robin Gandy, Donald Michie, and Jeannine Alton, together with other members of the A.M. Turing Trust, who have helped me to marshal support and resources for my endeavour from the start. Others, since 1977, have also played parts of vital significance for this book; but I retain a special gratitude for those who were prepared to assist me at a time when I had nothing but a shaky idea. I should add that the use I have made of this assistance is, of course, entirely my own responsibility; the interpretation I offer of material made available to me is likewise my own.
The enlarged Turing archive in King’s College, at first sight thin, has indeed provided a backbone of documentary material. Here an acknowledgement is due to Alan Turing himself; he kept nothing in the way of form letters, or the general accretion of correspondence overtaking those rising on the academic scale. But he took care to retain markers of most of the main points in his intellectual life. Indeed he had kept the star globe and the zeta-function machine gear wheels, although these were disposed of after his death. So interested in learning and development, he certainly cared about his own past.
So much, then, for what was already collected together in 1977. My own enquiries have since elicited further documents from a number of private and public sources, and meanwhile the growing interest in computer history has had the effect of giving me the benefit of recent Turing-related work by other researchers. Yet still the documentary evidence, in itself, would not add up to a portrait of Alan Turing. Only by meeting so many people who knew him could this picture have been drawn. Here again a first acknowledgment must go to my subject himself, who left behind a fund of goodwill on which I have repeatedly drawn. But in describing this aspect of my work, the word for what I have gained is less ‘information’ than ‘experience’.
The work of compiling this string of symbols on my typewriter has been very different from anything performed by a computer, and different too from my mathematical work in the way that it has required so much interference with other people’s lives. If this book is truly a biography – a writing of life, not a collection of facts – then it is because people have been prepared to allow that interference, and to entrust me with words and ideas that still have living force. The act of disturbing what was a strange kind of Sleeping Death had in fact involved some difficult – and often rather moving – moments. Thus Mr Arnold Murray, in conveying his recollections to me, was also shedding an albatross that had hung around his neck for twenty-five years. For he had returned to Manchester in 1954, only to be confronted by the news of Alan Turing’s death. He was made to feel that he was to blame; and being both particularly vulnerable, and entirely unaware of a larger context, accepted a profound and unmentionable guilt. His success as a musician in the 1960s, and his movement into married life, could not resolve a trauma which had to wait until 1980 for enlightenment.
This one example must suffice to indicate why, in a number of cases, my gratitude to people who have helped me goes well beyond the terms of a conventional acknowledgment. In some cases this will be abundantly clear from the text; in others the true nature of the debt will be invisible. Nor is the following list even complete; but I should like to thank these and other contributors to my picture of Alan Turing for all that they have done:
J. Anderson, James Atkins, Don Atkinson, Bob (once Augenfeld), Patrick Barnes, John Bates, S.G. Bauer, Donald Bayley, R. Beadon, G. Black, Victor F. Beuttell, Matthew H. Blamey, R.B. Braithwaite, R.A. Brooker, W. Byers Brown, Mary Campbell (née Wilson), V.M. Cannon Brookes, David Champernowne, A. Church, Joan (née) Clarke, F.W. Clayton, John Croft, Donald W. Davies, A.S. Douglas, Roy Duffy, D.B.G. Edwards, Ralph Elwell-Sutton, D.B. Eperson, Alex D. Fowler, T.H. Flowers, Nicholas Furbank, Robin Gandy, A. Gleason, A.E. Glennie, Harry Golombek, Jack Good, E.T. Goodwin, Hilla Greenbaum, Philip Hall, FRS, Arthur Harris, David Harris, Kenneth Harrison, Norman Heatley, Peter Hilton, F.H. Hinsley, Peter Hogg, N.E. Hoskin, H.D. Huskey, Neville Johnson, R. V. Jones, FRS, W.T. Jones, T. Kilburn, FRS, Leo Knoop, Walter H. Lee, Sir James Lighthill, FRS, R. Lockton, D.C. MacPhail, Malcolm MacPhail, Sir William Mansfield Cooper, A.V. Martin, P.B.C. Matthews, FRS, W. Mays, P.H.F. Mermagen, J.G.L. Michel, Donald Michie, Sir Stuart Milner-Barry, Rupert Morcom, Arnold Murray, D.Neild, E.A. Newman, M.H.A. Newman, FRS, John Polanyi, FRS, F.V. Price, J.W.S. Pringle, FRS, M.H.L. Pryce, FRS, David Rees, FRS, B. Richards, T. Rimmer, K. V. Roberts, Norman Routledge, David Sayre, Claude E. Shannon, Christopher Steed, Geoff Tootill, J.D. Trustram Eve, W.T. Tutte, Peter Twinn, S. Ulam, J.S. Vine, A.G.D. Watson, Mr and Mrs R.V.B. Webb, W. Gordon Welchman, A.C. Wesley, Patrick Wilkinson, J.H. Wilkinson, FRS, Cicely Williams (née Popplewell), R. Wills, Mike Woodger, Shaun Wylie.
It would be impossible to list all those who, besides these first-hand witnesses, have helped me by answering enquiries, commenting on draft, and in many other ways. But I should like to mention:
A.D. Childs (Sherborne School), J.E.C. Innes (Old Shirburnian Society), V. Knowles (Manchester University), Simon Lavington (Department of Computer Science, Manchester University), David Leigh (The Guardian), Julian Meldrum (Hall-Carpenter Archives, London), J.E. Taylor (National Archives, Washington), Christopher Andrew, Duncan Campbell, Martin Campbell-Kelly, Peter Chadwick, Stephen Cohen, Cy Deavours, Robin Denniston, Fisher Dilke, D. Dunnill, James Fleck, Steven Hicks, David Hutter, David Kahn, Peter Laurie, Sir Bernard Lovell, FRS, J. Maunder, Roger Penrose, FRS, Felix Pirani, Brian Randell, Jeffrey Weeks.
One other person, however, has played a decisive role in translating my ideas into the practical form of a book. This is Piers Burnett, who was responsible for commissioning me to write this book, and has seen me through all its difficulties, reading and advising on numerous drafts. Originally my contract was with André Deutsch Ltd, of which Piers Burnett was a director, and which advanced £5500 for the book. (Certain difficulties arising in 1981 on the completion of my work, made a transfer necessary. The first British edition was published by Burnett Books, in association with the Hutchinson Publishing Group.) I have had no grant or subsidy from any other source. While this was by publishing standards a generous investment, and one which made the difference between the existence and the non-existence of this book, it did not easily cover my two years of full time work from 1978 to 1980. Everything had to be done in a Turingesque shoestring style. There may be some virtues in this constraint, but it has certainly placed me in debt to many friends and friends of friends. My archive research and interviews in North America, for instance, would have been well-nigh impossible if I had not been given so many places to stay. At home I have also demanded great patience from those (particularly Peter Chadwick and Steve Hicks) who have had to share the tension and anxiety without the satisfactions.
Besides Piers Burnett there have been certain other people who somehow could see what I saw in this work, and who supplied a kind of moral support without which I could hardly have continued. One of these people commented very helpfully, at a critical stage, that I ought to leave at least something for others to find out! Certainly there are gaps, and trails I never followed. There will also be errors, though none I hope too serious, both of commission and omission. Perhaps, if the micro-electronic revolution brings about the end of the printed book, it will become possible to undertake continuous revision of published work. Meanwhile, a line must be drawn around an imperfect creation, in the knowledge that Turing scholarship has yet far to go. I shall transfer the documentary material I have accumulated to the Contemporary Scientific Archive Centre, for deposit at King’s College, Cambridge; and I shall likewise pass on corrections and additions that I may receive in the future. Perhaps as important, however, to the continuation of Turing studies, is the fact that as the world changes so will its perception of who Alan Turing was. Even while writing this book the word ‘computer’ has changed its social meaning: a universal machine with the scale and speed of the ACE he envisaged is now sitting on my desk, hardly bigger than my hand. The algorithms embodied in the Bombes now amount to no more than a few lines of BASIC. Personal interaction with a private computer, with its little battles over storage and displays and checking, is now an experience common to hundreds of thousands of people. There is no knowing what this may lead to, but it has changed our perception of the past. If genetic engineering makes advances comparable to those of information technology, then again, his later work may appear in quite a new light.
Alan Turing presumably thought that eventually a machine would be capable of writing a book such as this. In his 1951 radio talk, set against the opening of the Festival of Britain, he commented that ‘It is customary … to offer a grain of comfort, in the form of a statement that some peculiarly human characteristic could never be imitated by a machine. I cannot offer any such comfort, for I believe that no such bounds can be set.’ There was an element here of épater les bourgeois, especially when he gave as example of a peculiarly human quality, that of being ‘influenced by sex appeal’. Yet he was quite serious in describing the ‘almost certain’ advent of intelligent machines as a development ‘which can give us anxiety’ of a kind much more urgent than that of the Darwinian fright of a century before ‘that we might be superseded by the pig or the rat.’
In actual fact I should gladly have surrendered my technical problems to a machine – and a word processor would have saved weeks of chopping and gluing – but these have not been the real difficulties in the composition of this book. More pressing, to give just one very pertinent example, has been the need to overcome the twentieth century chasm between scientific thought and human life – moreover to resist the strong view held in certain quarters that my book should actually reinforce that separation. I have had to live, and even to struggle a little, for my vision; to put this point of view I have had to act this point of view.
One event of particular interest for me while working on these ideas was the appearance of Douglas Hofstadter’s Godel, Escher, Bach in 1979. It put my work in a Tangled Loop, for central to his book is its exploration of a topic I have brushed aside – the significance of Gödel incompleteness and Turing undecidability for the concept of Mind. I do not myself believe that these results, concerning as they do infinite, static, undisturbed logical systems, have any direct consequence for our finite, dynamic, interacting brains. Far more significant, in my view, is the limitation of human intelligence by virtue of its social embodiment – and this is a problem relegated to a marginal place in Hofstadter’s work as in so many other accounts, though I have placed it at the centre of my own. The study of Alan Turing’s life does not show us whether human intelligence is limited, or not limited, by Gödelian paradoxes. It does show intelligence thwarted and destroyed by its environment. But why, as Alan Turing might have put it, should machine intelligence be any less constrained by worldly reality? Indeed, there seems every reason to suppose that the clever machine will accommodate itself to the crazy demands of the political system in which it is embodied. In the academic sanctuary it is too easy to concentrate on infinitely more theoretical considerations.
For this reason my anxieties are rather different from those Alan Turing referred to: what worries me most is not whether we say machines are ‘thinking’ or not, but the place of such ‘thought’ in the body politic. Given the state of our modern Heartbreak House, I fear a victory not of anyone’s intelligence, but of the pig and the rat.
* For mathematicians he has immortality through the expression Turing machine. Many people must have used his name without any conception of his historical existence – the nearest thing to the life as a disembodied spirit that he once pondered on. Going even further, modern papers sometimes employ the usage of turing machine. Sinking without a capital letter into the collective mathematical consciousness (as with the abelian group, or the riemannian manifold) is probably the best that science can offer in the way of canonisation.
* But she did this very carefully, and only when trying to draw connections did the facade of intelligence fail. Even so, the jigsaw puzzling had more the effect of omitting and diminishing much of what he had done, rather than suggesting that he had done something more than was in fact the case. There was just one point where a definitely misleading statement resulted: cribbing a phrase by Philip Hall which in fact referred to the zeta-function machine, and setting it in a different context, she led readers to deduce that Alan had set about constructing a universal machine before the war. This no doubt encouraged A. Cave Brown in Bodyguard of Lies to suggest that he had done so in order to decode the Enigma. This suggestion then appeared as fact in J. Rohwer, The Critical Convoy Battles of 1943. Thus one sees a myth being made. The trouble is that truth does not reside in strings of symbols on the page; the business of interpreting them correctly requires experience.
† Though Geoffrey O’Hanlon had spilt the beans in 1954, writing in his obituary of Alan in The Shirburnian that ‘During the war he was engaged in breaking down enemy codes. … His work was hush-hush, not to be divulged even to his mother.’
* Perhaps, however, the magic of the 1940s could never be recaptured amidst the dull white heat of the 1960s technological revolution. And perhaps the closest evocation of the Turing spirit in this period was not in science, but in science fiction – a cinematic Back to Methuselah. The date of 2001 A Space Odyssey was presumably taken from the fifty-year prophecy in the Mind paper, which was specifically cited in Arthur C. Clarke and Stanley Kubrick’s book. Their picture of HAL was essentially based on Turing ideas; and, quite uncannily, their plot had HAL destroyed by ‘the logic of the planners’, whose ‘twin gods of Security and National Interest meant nothing to HAL. He was only aware of the conflict that was slowly destroying his integrity – the conflict between truth, and concealment of truth.’
* This is not always appreciated. Thus a typical view emerges in The Mighty Micro by Christopher Evans (Gollancz 1979), which was perhaps the first widely disseminated mention of the trial:
… he came to a tragic end. A solitary individual who confided little in other people, he was also a practising homosexual at a time when homosexuality was viewed as a criminal offence. Somehow he brushed with the law – the sad, sorry details are hard, and perhaps unnecessary to come by – and one evening, depressed and disillusioned, he retired to his room and bit into an apple laced with potassium cyanide.
But in 1977 Lord Halsbury had led the defeat of an attempt to reduce the ‘age of consent’ to eighteen – and any kind of street encounter, whether or not involving money, is still illegal. Prosecutions for homosexual offences, furthermore, have roughly trebled since 1967, and currently run at twice the 1952 level. State control of sexuality has changed since the 1950s, but the elements of youth and of street life are ‘viewed as’ crimes as much now as then. More directly pertinent to the theme of The Mighty Micro is that the computer has facilitated a far more comprehensive process of ‘brushing with the law’, with ‘sad, sorry details’ filed away for the police, employers and security officials quite regardless of whether crimes have been committed. The process of positive vetting, in particular, is supposed to prevent a homosexual ever again having access to anything of state importance. Whatever the arguments, these are not issues of the past. Nor is the ‘detail’ of chemical castration a dead question. But even prophets of the ‘information explosion’ can exhibit a wish not to know.
* Twistors, as geometric objects which allow the formulation of a different description of space and time from the usual one, are not quite ‘Hyperboloids of wondrous Light’. But they are based on light rays and an objective of twistor theory is the unification of general relativity and quantum mechanics. So the last Turing messages have a special resonance for me. And the privilege of working in so dramatically original a theory, and studying under such a person, has been a vital ingredient in my approach to Alan Turing.
* Some have not been preserved; thus conspicuously absent is any announcement of his engagement in 1941. Mrs Turing also performed some half-hearted censorship on the letters, which like all incomplete suppression merely draws attention to the anxieties of the censor. Only one sentence, probably a reference to the engagement, is actually rendered illegible. I also feel a distinct debt to Lyn Newman for a subtle moral encouragement: in her introduction to Mrs Turing’s book she called it ‘a source-book for a future biographer’, which is exactly how I have used it.