Alan Turing: The Enigma The Centenary Edition

743 Pages·2012·5.83 MB·English

by  Andrew Hodges

ALAN TURING: THE ENIGMA
Andrew Hodges is Tutor in Mathematics at Wadham College, Oxford University.
His classic text of 1983, since translated into several languages, created a new
kind of biography, with mathematics, science, computing, war history,
philosophy and gay liberation woven into a single personal narrative. He is an
active contributor to the mathematics of fundamental physics, as a follower of
Roger Penrose. See www.turing.org.uk for further material.
TO THEE OLD CAUSE!
The dedication, epigraphs, and epitaph are taken from the Leaves of Grass of
Walt Whitman.
‘Alan Turing was by any reckoning one of the most remarkable Englishmen of
the century. A brilliant mathematician at Cambridge in the ’30s, Turing
discovered that his was precisely the kind of intelligence needed by Britain
during the war and became the presiding genius at Bletchley Park, the boffin
centre which cracked the German Enigma code. (A character in McEwan’s The
Imitation Game was loosely based on him.) There he became obsessed by the
notion of machine intelligence and was, in effect, the father of the modern
computer. Mistrust and bureaucracy, however, frustrated many of his plans after
the war, when Turing was to discover that though he was the master of his own
sphere, politically he remained as his was in 1941 − a servant. A homosexual,
Turing found his own morality and scientific ideas increasingly at odds with the
values of the state which he served. Eventually, he committed suicide. Andrew
Hodges’s book is of exemplary scholarship and sympathy. Intimate, perceptive
and insightful, it’s also the most readable biography I’ve picked up in some time’
Richard Rayner, Time Out ‘Researched and written extraordinarily well. It is a
first-class contribution to history and an exemplary work of biography’
Nature
‘Life and work are both made enthralling by Hodges, himself a scientist’
Sunday Times
‘This rather shadowy figure has now finally been lifted into the light of day … it
has to be said that Andrew Hodges has put together an extraordinary story’
Sunday Telegraph
‘This book has a great deal to offer: clear technical descriptions set against their
backgrounds; the story of a man largely at odds with the system he lived in: and
the puzzle of Alan Turing himself’
Times Higher Education Supplement
‘Andrew Hodges, in this fine biography Alan Turing: The Enigma, brings Turing
the thinker and Turing the man alive for the reader and thus allows us all to share
in the privilege of knowing him’
Financial Times
‘This is not a book to be argued about. It is a book to be read’
New Scientist
‘A major work at any level. Recommended’
Personal Computing World
THE CENTENARY EDITION
With a foreword by Douglas Hofstadter and a new preface by the author
ANDREW HODGES
Alan Turing: The Enigma
Published in the United States by Princeton University Press, 41 William Street, Princeton, New Jersey
08540 press.princeton.edu First published in 2012 by Vintage, Random House, 20 Vauxhall Bridge Road,
London SW1V 2SA www.vintage-books.co.uk
Copyright © 1983 by Andrew Hodges
Preface to the 2012 Centenary edition copyright © 2012 by Andrew Hodges
Foreword copyright © 2000 by Douglas Hofstadter All Rights Reserved
First published by Burnett Books Ltd in association with
Hutchinson Publishing Group, 1983
Unwin Paperbacks edition, 1985
Reprinting, 1985 (twice), 1986, 1987 (twice)
First published by Vintage in 1992
Library of Congress Control Number 2012935958
ISBN 978-0-691-15564-7
Printed on acid-free paper. ∞
Printed in the United States of America 1 3 5 7 9 10 8 6 4 2
Contents
List of Plates
Foreword by Douglas Hofstadter
Preface to the 2012 Centenary edition
PART ONE: THE LOGICAL
1 Esprit de Corps to 13 February 1930
2 The Spirit of Truth to 14 April 1936
3 New Men to 3 September 1939
4 The Relay Race to 10 November 1942
BRIDGE PASSAGE to 1 April 1943
PART TWO: THE PHYSICAL
5 Running Up to 2 September 1945
6 Mercury Delayed to 2 October 1948
7 The Greenwood Tree to 7 February 1952
8 On the Beach to 7 June 1954
Postscript
Author’s Note
Notes
Acknowledgements
Index
List of Plates
1. Alan’s father, Julius Turing (John Turing)
Alan Turing with his brother John, St Leonard’s, 1917 (John Turing)
Alan with his mother in Brittany, 1921 (John Turing)
2. Colonel and Mrs Morcom with Christopher, 1929 (Rupert Morcom)
Alan Turing with two school contemporaries, 1931 (Peter Hogg)
Alan Turing in 1934 (John Turing)
3. Alan Turing with his parents, 1938 (John Turing) Sailing at Bosham,
August 1939 (John Turing)
4. The naval Enigma machine
5. A Colossus machine in operation at Bletchley Park, 1944-5 (HMSO)
The Delilah terminal, 1945 (HMSO)
6. Finish of a three-mile race, 1946 (King’s College, Cambridge) The Pilot
ACE computer in 1950
7. The prototype Manchester computer, 1949 (Department of Computer
Science, University of Manchester)
Alan Turing at the console of the Ferranti Mark I computer, 1951
(Department of Computer Science, University of Manchester)
Robin Gandy in 1953 (Robin Gandy)
8. Alan Mathison Turing, Fellow of the Royal Society, 1951 (King’s College,
Cambridge and The Royal Society)
Foreword
Is a mind a complicated kind of abstract pattern that develops in an underlying
physical substrate, such as a vast network of nerve cells? If so, could something
else be substituted for the nerve cells − something such as ants, giving rise to an
ant colony that thinks as a whole and has an identity − that is to say, a self? Or
could something else be substituted for the tiny nerve cells, such as millions of
small computational units made of arrays of transistors, giving rise to an
artificial neural network with a conscious mind? Or could software simulating
such richly interconnected computational units be substituted, giving rise to a
conventional computer (necessarily a far faster and more capacious one than we
have ever seen) endowed with a mind and a soul and free will? In short, can
thinking and feeling emerge from patterns of activity in different sorts of
substrate − organic, electronic, or otherwise?
Could a machine communicate with humans on an unlimited set of topics
through fluent use of a human language? Could a language-using machine give
the appearance of understanding sentences and coming up with ideas while in
truth being as devoid of thought and as empty inside as a nineteenth-century
adding machine or a twentieth-century word processor? How might we
distinguish between a genuinely conscious and intelligent mind and a cleverly
constructed but hollow language-using facade? Are understanding and reasoning
incompatible with a materialistic, mechanistic view of living beings?
Could a machine ever be said to have made its own decisions? Could a
machine have beliefs? Could a machine make mistakes? Could a machine
believe it made its own decisions? Could a machine erroneously attribute free
will to itself? Could a machine come up with ideas that had not been
programmed into it in advance? Could creativity emerge from a set of fixed
rules? Are we − even the most creative among us − but passive slaves to the laws
of physics that govern our neurons?
Could machines have emotions? Do our emotions and our intellects belong
to separate compartments of our selves? Could machines be enchanted by ideas,
by people, by other machines? Could machines be attracted to each other, fall in
love? What would be the social norms for machines in love? Would there be