Alan Turing: The Enigma
by Andrew Hodges, Douglas Hofstadter

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Book Reviews of Alan Turing: The Enigma

Book Review: Definitive biography of an uncommonly interesting subject
Summary: 5 Stars

The turning point in the greatly increased apprecation for Turning was the publication of this biography by Hodges, originally in 1983. Lapsing out of print until recently, it would be no exaggeration to say that this book sparked a widespread reappraisal of Turing in an age more able to understand him, both professionally and personally. (It would be difficult, for example, to cite any other scientific biography which inspired a play that was performed in London and on Broadway in New York: "Breaking the Code," written by Hugh Whitemore in 1988, and which was made into a 1997 television play that is available on VHS.) It is difficult to imagine that this biography will be allowed to go out of print again.

Turing's key contribution to computer science was in realizing that computers are not merely number crunchers, but were capable of manipulating general purpose symbols. Certainly, it is natural to represent numbers with symbols inside computing machines, especially because there is such a universally accepted habit of working number symbols with pen and paper. In achieving this critical insight that the symbols inside computers are perfectly general, Turing tied computer science into a large body of traditional work in mathematics reaching back centuries to the work of Leibniz and encompassing the more recent work of such logicians as Boole, Frege, Russell, and Godel. Less widely understood is that it is this same general purpose representational characteristic of computers which has made possible the applications of computers which matter to people, from e-mail and the web to digital music and the little box that decides whether to deploy the airbag in your car.

Contemporaries of Turing tended to see the computer as a sort of automatic adding machine, suitable for calculating ballistics tables and little else. Yet Turing had completed most of the underpinning for his Theory of Computation before the onset of the Second World War, when he was called upon to build a secret computer for cryptanalytic purposes. The very fact that Turing wondered how to decide if a machine could be said to "think," which was the subject of his famous "Turing Test," was itself a revolutionary idea, the question being more significant at the time than any answer.

To a large extent, the ideas first articulated by Turing, regardless of how directly or indirectly their influence has been felt, are at the root of a changed perception of the world which we now all share at the beginning of the 21st Century. This view of the world as a kind of computer has replaced the industrial era view of the world as a kind of clockwork machine. We are all, in effect, on a quest to find out which propositions are "computable" and "decidable."

Combined with this substantial reassessment of Turing's professional contributions, there has been an enormous change in the way British and American society have come to perceive homosexuality. Viewed as a psychological disease and a criminal act at the time of Turing's difficulties with the law, Britain would decriminalize private consensual homosexual relations a few years after his death and begin recognizing a civil liberties interest emerging at about the time of the initial publication of Hodges' book. This gulf of decades has come to reinforce a view of Turing as a man very much outside of his own time, almost constitutionally incapable of thinking as convention would dictate about anything at all.

It is a great irony that the Allied war effort -- and perhaps the Cold War effort -- could not abide a man whom it viewed as a security risk, despite the undeniable fact that his work at a minimum saved a great many lives and quite probably shortened the war. Indeed, it is a great tragedy that the democratic state he helped to save then turned and ungratefully persecuted him, likely driving him to his death.

Few scientific biographies possess the massive sweep of human drama in the crucible of history, and few biographical subjects warrant such treatment. Turing and his definitive biography by Hodges are emphatic exceptions.

Summary of Alan Turing: The Enigma

Alan had proved that there was no "miraculous machine" that could solve all mathematical problems, but in the process he had discovered something almost equally miraculous, the idea of a universal machine that could take over the work of any machine.

During World War II, Turing was the intellectual star of Bletchley Park, the secret British cryptography unit. His work cracking the German's Enigma machine code was, in many ways, the first triumph of computer science. And Turing died because his identity as a homosexual was incompatible with cold-war ideas of security, implemented with machines and remorseless logic: "It was his own invention, and it killed the goose that laid the golden eggs."

Andrew Hodges's remarkable insight weaves Turing's mathematical and computer work with his personal life to produce one of the best biographies of our time, and the basis of the Derek Jacobi movie Breaking the Code. Hodges has the mathematical knowledge to explain the intellectual significance of Turing's work, while never losing sight of the human and social picture:

In this sense his life belied his work, for it could not be contained by the discrete state machine. At every stage his life raised questions about the connection (or lack of it) between the mind and the body, thought and action, intelligence and operations, science and society, the individual and history.

And Hodges admits what all biographers know, but few admit, about their subjects: "his inner code remains unbroken." Alan Turing is still an enigma. --Mary Ellen Curtin

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