Part 1 of Turing: a natural philosopher  (1997)

Introduction

Alan Turing's immersion in and attack upon Nature was a unity; divisions between mathematics, science, technology and philosophy in his work have tended to obscure his ideas. He was not a prolific author; much remained unpublished in his lifetime; some remained secret into the 1990s. Private communications shed a little more light on the development of his thought, a subject on which he was generally silent. We shall see, for instance, how he came to logic and computation from a youthful fascination with the physical description of mind. But we have only hints as to the formation of his convictions amidst the secrecy of wartime cryptanalysis, and suggestions of fresh ideas are lost in the drama of his mysterious death.

The Nature of Turing's World

His experimental chemistry incurred displeasure, as did poor handwriting and unconventional methods in his mathematics. He was bottom of the form in English. The headmaster wrote, 'If he is to stay at a Public School, he must aim at becoming educated. If he is to be solely a Scientific Specialist, he is wasting his time at a Public School' and this judgment on British ruling-class priorities was almost correct. Turing was nearly prevented from taking the equivalent of GCSEs. Thereafter, he found his level in Einstein's own exposition of Relativity and Eddington's view of quantum mechanics in The Nature of the Physical World. But this was isolated private study, and he might never have felt the urge to communicate but for an impossibly romantic story.

Human nature brought him to life; but it was his own homosexual nature, bringing revelation and trauma in equal measure. He fell in unrequited love with Christopher Morcom, a very talented youth in the school sixth form, and his longing for friendship brought him to communicate. A brief flowering of scientific collaboration perished when Morcom suddenly died in February 1930. Turing's correspondence with the dead boy's mother gives insight into the development of his ideas in the aftermath. He was concerned to believe the dead boy could still exist in spirit, and to reconcile such a belief with science. To this end he wrote for Mrs Morcom an essay, probably in 1932. It is the private writing of a twenty-year-old, and must be read as testament to background and not as a thesis upheld in public; nevertheless it is a key to Turing's future development. [2]

NATURE OF SPIRIT

It used to be supposed in Science that if everything was known about the Universe at any particular moment then we can predict what it will be through all the future... More modern science however has come to the conclusion that when we are dealing with atoms and electrons we are quite unable to know the exact state of them; our instruments being made of atoms and electrons themselves. The conception then of being able to know the exact state of the universe then must really break down on the small scale. This means that the theory which held that as eclipses etc. are predestined so were all our actions breaks down too. We have a will which is able to determine the action of the atoms probably in a small portion of the brain, or possibly all over it. The rest of the body acts so as to amplify this...

In stating the classic paradox of physical determinism and freewill, Turing is influenced by Eddington's assertion that quantum mechanical physics ('more modern science') yields room for human will. Eddington asked how could 'this collection of ordinary atoms be a thinking machine?' and Turing tries to find some answer. His essay goes on to espouse belief in a spirit unconstrained by the body: 'when the body dies the 'mechanism' of the body, holding the spirit is gone and the spirit finds a new body sooner or later perhaps immediately.' Letters show he retained such ideas at least until 1933.

Turing was much more successful in undergraduate work than at school, and King's College lent him a protective ambience sympathetic to homosexuality and unconventional opinion. He was not, however, one of its élite social circle, nor in a political group. Politically, he responded briefly to the 1933 Anti-War movement, but not to the Communist party as others of his close acquaintance did. Nor did Turing share the pacifism of his first lover, fellow mathematics student James Atkins.

In a similar way Turing found a home in Cambridge mathematical culture, yet did not belong entirely to it. The division between 'pure' and 'applied' mathematics was at Cambridge then as now very strong, but Turing ignored it, and he never showed mathematical parochialism. If anything, it was the attitude of a Russell that he acquired, assuming that mastery of so difficult a subject granted the right to invade others. Turing showed little intellectual diffidence once in his stride: in March 1933 he acquired Russell's Introduction to Mathematical Philosophy, and on 1 December 1933, the philosopher R. B. Braithwaite minuted in the Moral Science Club records: 'A. M. Turing read a paper on 'Mathematics and logic.' He suggested that a purely logistic view of mathematics was inadequate; and that mathematical propositions possessed a variety of interpretations, of which the logistic was merely one.' At the same time he was studying von Neumann's 1932 Grundlagen den Quantenmechanik. Thus, it may be that Eddington's claims for quantum mechanics had encouraged the shift of Turing's interest towards logical foundations. And it was logic that made Alan Turing's name.

[1] Letter to Turing's mother, Mrs E. Sara Turing, now in the Turing Archive at King's College, Cambridge.
[2] A copy of Turing's undated manuscript Nature of Spirit is also in the Turing Archive.

© 1997, Andrew Hodges.

CONTINUE to part 2

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