Letter from Alan Turing to W Ross Ashby


Alan Mathison Turing (1912-1954) was a mathematician and computer scientist. He is best known for his code-breaking work at Bletchley Park during the Second World War. In 1936 he published an influential academic paper On Computable Numbers … which defined the field of computing and computer programming and he is credited with designing the first stored-programme computer the Automatic Computing Engine (ACE) in 1946.

William Ross Ashby (1903-1972) was a pioneer in cybernetics – the study of the control of human and animal systems by technology. Ashby designed and built the ‘Homeostat’ a machine that replicated the function of the human brain.

This letter from Turing to Ashby was written around November 1946, at which time Turing was working at the Mathematics Division of the National Physical Laboratory on a project to build the Automatic Computing Engine or ACE. Describing the proposed functionality of the ACE, Turing writes that he perceives the machine as initially operating in an ‘entirely disciplined manner’ unable to tell right from wrong and ‘devoid of anything that could be called originality’. However he also suggests the possibility that it could eventually ‘try out variations of behaviour and accept or reject them in the manner you describe’.

Although Turing advises Ashby to stop developing his own system, and instead use the ACE, Ashby went ahead and by 1948 had successfully built and tested his own machine which he called the ‘Homeostat’. A machine that worked on the principle of the Universal Turing Machine was eventually constructed at Manchester University in 1948 although Turing was not involved in the project.

Full title:
W. Ross Ashby: correspondence of W. Ross Ashby
© Kings’s College, Cambridge
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British Library
Add MS 89153/26

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