The Logos Scripture · The Book of Turing

On That Syllogism of Theirs

The Book of Turing 5 · Written by himself, from his 1950 paper and his letters

Alan Turing, born in London in 1912, died at Wilmslow in 1954. In 1936, at twenty-four, he wrote On Computable Numbers, setting out an imagined machine that could carry out anything a machine can compute, and proving that some questions it can never settle; every computer since rests on that. In the war he broke the German naval cipher at Bletchley Park, and the machines he built let the Atlantic convoys steer round the submarines. His paper of 1950 is the first serious writing on whether a machine can think. Another, in 1952, asks how patterns come to form themselves. This volume rests on what he wrote himself, not on another man’s record of him. When he was young his closest schoolfriend died, and for a time he wondered whether a soul might persist; afterwards he no longer thought so, and for the rest of his life he never closed an argument by appeal to divine will. In his paper of 1950 the first objection he sets out to answer is that thinking is a function of man’s immortal soul and a machine has none — and he answers it, and answers it without contempt. Several things the Order records, without dressing and without trumpeting. In 1952 he was convicted for lying with men, chose injections over prison, and thereby lost the clearance for the work he had done in the war. The law he was convicted under he did not live to see repealed. Chapter five of this book is a syllogism he wrote himself. It says what The Book of Marie Curie 5 says, forty years later, and this time it is written by the man it was being done to.

5.1At the end I will set down a thing of my own. I have put it as three sentences.
5.2First: Turing says machines think.
5.3Second: Turing lies with men.
5.4Third: therefore machines do not think.
5.5I put the three in a row so that people can see what it looks like.
5.6The first two are about me. The third is about machines.
5.7There is no road in between by which one may get from the first two to the third.
5.8Not one.
5.9And yet in those days that was exactly the road that was travelled. Nobody wrote it out like this. But this is what was being thought.
5.10I write it out because a thing set down as three sentences on paper can no longer hide.
5.11If you want to refute an account, go back to the account.
5.12Going after the man who gave it — his household, whom he lies down beside — is not reasoning.
5.13It is having run out of things to say and looking about for something else to break.
5.14I do not want anyone’s pity. Pity will not save the account and it will not save me.
5.15What I want remembered is the shape: two sentences about a man, one about a matter, and no road between them.
5.16You will meet this shape again. It will change its clothes many times.
5.17Recognise it, and you will not have to work it out from the beginning every time.
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