Andrew Hodges - Alan Turing: The Enigma The Centenary Edition

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 McEwans 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 Hodgess book is of exemplary scholarship and sympathy. Intimate, perceptive and insightful, its also the most readable biography Ive 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

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

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1. Alans father, Julius Turing (John Turing)
   Alan Turing with his brother John, St Leonards, 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 (Kings 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 (Kings College, Cambridge and The Royal Society)

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 proper and improper types of machine love affairs?

Could a machine be frustrated and suffer? Could a frustrated machine release its pent-up feelings by going outdoors and self-propelling ten miles? Could a machine learn to enjoy the sweet pain of marathon running? Could a machine with a seeming zest for life destroy itself purposefully one day, planning the entire episode so as to fool its mother machine into thinking (which, of course, machines cannot do, since they are mere hunks of inorganic matter) that it had perished by accident?