WHILE OUT FOR A RUN, Alan Turing conceived of the computer. He wasn’t mid-stride when he did it. By his own recollection, he was taking a break, lying in a meadow near Grantchester, a few miles south of King’s College.
He saw that any mathematical operation that could be performed by the teeming neurons of a human brain could also be worked out by a single machine with only three capabilities: distinguishing between two symbols, traversing a series of those symbols and swapping one for the other. With this insight, he had invented a method by which to offload humanity’s entire wealth of formalized logic onto a discrete cluster of inorganic matter. By his own estimation, he had found a way to share thought itself with the bloodless parts of the universe.
As Andrew Hodges writes in his still-definitive 1983 biography, Alan Turing: The Enigma: “His machines — soon to be called Turing machines — offered a bridge, a connection between abstract symbols, and the physical world.” Hodges’ book was reissued in honor of the June 23, 2012, centenary of Alan Mathison Turing’s birth, a marker that touched off a variety of celebrations and reassessments of the marathon-running, code-breaking, man-loving war hero’s life. Among the most apt of these was an interactive Google doodle that offered a very close replica of a Turing machine in its original conception.
Hodges addresses Google’s debt to Turing in his new preface to the book: “Online search engines, which work with such astonishing speed and power, are algorithms, and so equivalent to Turing machines. They are also descendants of the particular algorithms, using sophisticated logic, statistics and parallel processing, that Turing expertly pioneered for Enigma-breaking. These were search engines for the keys to the Reich.”
The Enigma referred to here is the machine that the Germans used to encrypt military transmissions during WWII — a kind of modified typewriter that bounced a letter through an ever-shifting series of circuits until it flashed onto a lampboard as a many-times-abstracted cipher. Germany’s confidence in its ciphers’ impenetrability never faltered. In terms of immediate impact on the lives of “pink-colored collections of sense-data” (Turing´s half-joking phrase), it was Turing’s work on cracking and re-cracking the Enigma that represents his most momentous achievement. Now, no one doubts Hodges’ assertion that Turing’s design and implementation of the machine that undid the Enigma — capable as it was of rapidly dispatching vast swaths of the German device’s quintillions of possible configurations — saved Allied lives and drastically altered the course of WWII. But during Turing’s lifetime, the history-altering work he performed for His Majesty’s Government was a secret to the public, a fact that made possible the many tragedies of his final years.
Pointing to a 2011 speech in which Barack Obama mentioned Turing in the same breath as Darwin and Newton, Hodges acknowledges in the new preface that “public recognition of Alan Turing [has] attained a level much higher than in 1983, when this book first appeared.” He’s right, but given the man’s impact on nearly every aspect of modern life, his profile is still mind-bogglingly low. As Hodges makes clear, Turing was the antithesis of a self-promoter, stubbornly believing that the merit of his thought alone should always be enough. This disregard for publicity, as well as the fact that his most sensationally patriotic work wasn’t revealed to the public until its urgency had passed, can account for some of the discrepancy between his significance and his renown.
However, it may well be that one fact alone accounts for most of our cultural amnesia — or indeed cultural suppression from the outset — regarding this man cum genius, a man who humiliated Nazis while running marathons at an Olympic level and who essentially did early R&D for our iPhones. Turing was conspicuously a homosexual — he couldn’t be bothered to hide this fact at a time when it was illegal to be out of the closet. He was also openly an atheist, which didn’t help. At a certain point in his life he grew breasts. And finally, held in contempt by the country he helped save, he killed himself.
It’s fortunate that Hodges had the passion and foresight to write his record at a time when so many who knew Alan Turing were still alive to aid in an attempt to decipher him (fortunate enough that a reader will likely feel a phantom apprehension at imagining what might have been lost if he hadn’t). Along with the new preface, the only addition to the centenary edition of Hodges’ exhaustive, inspiring, and at times tiring biography is a short and mostly dispensable foreword by the American philosopher and author Douglas Hofstadter. Without raising his pulse or ours, Hofstadter informs us that the book is “a first-rate presentation of the life of a first-rate scientific mind.” But Hodges’ own enthusiasm for his subject animates all of his 540 pages. An English mathematician himself, he never winces at a technicality, but he’s at his most gripping and expressive when describing the man’s tics and attitudes, the “voice that went up and down in pitch rather than in stress,” the ink-drenched collars.
Perhaps this is why the opening section on Turing’s childhood, whose intimacy and narrative cohesion is never again matched, remains the book’s most haunting. It gives early glimpses at his genius for abstraction: at 10 years old, he complained that during an introductory lesson to elementary algebra, his teacher “gave a quite false impression of what is meant by x.” And it makes good on the always-satisfying historical shaming of early naysayers. After catching him doing algebra during “religious instruction,” a teacher wrote, “I can forgive his writing, though it is the worst I have ever seen, and I try to view tolerantly his inexactitude and slipshod, dirty, work, inconsistent though such inexactitude is in a utilitarian, but I cannot forgive the stupidity of his attitude towards sane discussion on the New Testament.” But the chapter’s core is the devastating story of Turing’s first love, a boy named Christopher Morcom who bonded with Alan over science at boarding school. A few gentle warnings from Morcom that Turing might be showing him too much attention ensured that their relations never strayed far from the intellectual. The boys tracked comets together by post when they were separated during school breaks, and at the time of Morcom’s sudden and unexpected death from bovine tuberculosis, their friendship had only been deepening. In Hodges’ telling, the loss seems to crystallize Alan’s future, imbuing him with a sense of solemnity, and a drive to compensate for Morcom’s stifled brilliance, which would in effect help propel him into his mathematical career.
The recollections that Turing wrote soon after his friend’s death are among the most moving passages in the book; his plainly expressed longing for Morcom continues to reverberate as we see him drifting from one unrequited love and rebuffed advance to the next during his adult life. In a postscript to the condolence letter he sent to Morcom’s mother, Turing couldn’t restrain himself from asking for a photograph: “I should be extremely grateful if you could find me sometime a little snap-shot of Chris, to remind me of his example and of his efforts to make me careful and neat. I shall miss his face so, and the way he used to smile at me sideways. Fortunately I have kept all his letters.”
By the time WWII arrives and Alan agrees for the first time to “surrender a part of his mind, with a promise to keep the government’s secrets,” as Hodges puts it, the biography has shifted to a tone that is part political thriller and part math text.
Readers who take the time to internalize the technical details of Enigma-breaking will be rewarded with visceral insights into the kind of lateral thinking that can occasionally place a single, peculiar Englishman at the tiller of world history. This said, some sections will likely drag for laypeople with no special interest in cryptography or math. The reader can skim those sections. But it would be a mistake to fade away before learning that Turing asked for a teddy bear for Christmas months before he prefigured the computer age with his epiphany in the meadow; that he was moved to sponsor the boarding-school education of a young Jewish war refugee from Vienna, whom he proceeded to make an unsuccessful pass at; or that somewhere in the backwoods of Buckinghamshire are two bars of silver bullion that he buried as an insurance policy against a German invasion, encrypting instructions on their retrieval that mysteriously failed to turn up the treasure after the war.
The Enigma’s second half confronts us first with the slow-rolling bureaucratic indignities that Turing endured as he tried to realize, in collaboration with the British government, the first working version of the “universal machine” he dreamed up on his run, and then with the inconceivable cruelty of the punishment he suffered at the hands of the state for “gross indecency.” He earned this charge after a brief and perhaps naively optimistic (or perhaps just unlucky) affair with Arnold Murray, a working-class youth he met on the streets of Manchester. A friend of Murray’s who knew about the affair and understood that sex criminals didn’t enjoy the usual protections of the law saw an opportunity to burglarize an upper-middle-class man’s house. The thief wasn’t excessively greedy, but when Turing realized what had happened, he made the mistake of acting as an innocent man. He called the police and then quickly incriminated himself in describing the likely culprit as a friend of his boyfriend’s.
Turing went on to choose the absurd pseudoscience of a two-year estrogen treatment, smothered his libido, but not his sexuality, over jail time. At the time of his death on June 7, 1954, the treatment had been over for a year, and in the weeks leading up to that day, he had been working on new ideas, socializing within his small group of friends and in most other ways behaving in his usual, disproportionately good-humored manner. This information, as well as the fact that he was an increasingly visible homosexual in possession of important state secrets, has given rise to speculation that Turing’s death may not have been a suicide. But in Hodges’ account, the official judgment of a June 10 inquest — that Turing had poisoned himself with cyanide, apparently delivered in a partly eaten apple found by his bedside — emerges as the overwhelmingly likely reality, an outcome motivated by outside forces but not decided by them (Hodges does allow that the suicide may have been mercifully orchestrated to allow one person, Alan’s mother, to believe that it was an accident).
“I am forced to the conclusion that this was a deliberate act. In a man of his type, one never knows what his mental processes are going to do next,” wrote the coroner. And for his own reasons, Turing may have agreed with him. After all, during a 1952 BBC radio panel discussion on whether machines could think, he had said, “Thinking is those mental processes we don’t understand.”
Exposition of Turing’s uncompromising philosophy on the nature of thought and his foundational work in the field of artificial intelligence makes up the brighter spots of the book’s second half. The metaphysical provocations of the Turing Test, an exhilaratingly simple probe of machine intelligence, have only become more urgent since Alan proposed it in 1950. The test asserts that the best way to determine if a computer is really thinking is to ask it yourself, over and over again and in as many ways as you can devise, until either you satisfy your skepticism or the machine reveals itself as a hollow pretender to a human right.
Now that mass-marketed cell phones can survive a few rounds of the question game, it’s easy to lose sight of the fact that, for the father of computer science, the essential value of the field lay not in its everyday utility, but in its potential to elucidate the secrets of human thought. Turing once wrote, “I am more interested in the possibility of producing models of the action of the brain than in the practical applications of computing.” It is perhaps this tendency towards a purity of intellectual motivation — an effortless resolve to never retreat from the controversial to the marketable, from the truly mystifying implication to the merely useful application — that represents Turing’s most vital characteristic. Hodges’ contribution is to convey that fearlessness to future thinkers of all makes.