The best books to widen your picture of Alan Turing’s world

My first pick is the one most directly about Alan Turing himself. After 1950 his attention turned mainly to his new theory of mathematical biology, but his death in 1954 left most of this work unpublished.  His ideas were 20 or more years ahead of their time and few people could assess them. Jonathan Swinton is a leading expert in this field, and has been studying Turing’s manuscripts for 30 years. But his book has a much broader range: he adds so much on the culture of Manchester and its region, with a particular focus on women both as protagonists and observers. He has also illustrated his story with a wealth of pictures.

My second choice relates more subtly to Turing’s sudden end in 1954. In 1955, Turing’s colleague Max Newman gave a talk on logic in his honour. This greatly impressed a student, Roger Penrose, who was also studying the quantum mechanics and relativity that had first fascinated the young Turing. Years later, Penrose announced an astonishing thesis relating logic and physics. This book explains the theory he developed. It claims that the brain must exploit quantum-mechanical physics that no computer can emulate. Turing famously promoted the prospects for computer-based Artificial Intelligence, but he would have taken this anti-AI thesis more seriously than any other argument: it takes up his own interests and develops his own kind of thinking. 

Penrose’s books are not about science, they are actually doing scientific thinking. His humour and wonderful pictures enhance the direct personal engagement. The theory is highly controversial but has set a remarkable twenty-first-century agenda, inspiring new experiments to push at the boundaries in many fields.

Ray Monk has, like me, been drawn to the idea of a linear biographical narrative fusing life and work together. My third pick is his biography of the American physicist Robert Oppenheimer. This is a fascinating story parallel to Turing’s. The Second World War brought both of them, hitherto pure researchers, to intense and crucial involvement in the world’s affairs. Nuclear weapons for Oppenheimer were what codebreaking was for Turing. Afterward, both were at odds with the governments they had empowered.

When in 1953 Turing wrote ‘I detest America’ he might well have been reacting to the McCarthy period in which Oppenheimer was attacked. But Ray Monk treats Oppenheimer’s pure scientific work as seriously as the political story. Oppenheimer’s 1939 paper on black holes was the background to Penrose’s 1965 paper cited in the Nobel physics prize of 2020. These dates illustrate the deep and decades-spanning connections that are involved in fundamental scientific advances.

My fourth pick is another biography, of the economist John Maynard Keynes. Richard Davenport-Hines has divided up his account into ‘seven lives’. Yet by taking his personal life and sexual identity seriously, Davenport-Hines achieves an outstanding unification. Seriousness is not solemnity: readers will find here a delightful story about Keynes admiring Alan Turing’s fingernails at King’s College, Cambridge. There is much more to illustrate the extraordinary King’s College ambiance in which Turing found his home, and deeper connections: in late 1946, both were crossing the Atlantic, Keynes to rescue the British economy, Turing on his start-up of the computer industry. Keynesian economics are newly relevant now, but the liberal élite culture in which it was hatched may still surprise readers. When Turing started war work at Bletchley Park, he wrote to Keynes’s circle that Dillwyn Knox was ‘his boss’. Did he know, as Richard Davenport-Hines explains, that Knox had been Keynes’s first lover? He would have relished the revelation with glee.

My last pick is another critique of Artificial Intelligence, a forceful and well-documented account of what happens when algorithms are embodied in the real human world, with inputs and outputs inseparable from social constructs and political imperatives. In my view, this question was latent in Turing’s formulation of the concept of ‘intelligence’, and it is not going to go away. It was there in 1940, when Turing’s brilliant algorithms made British codebreaking possible: they depended for success on the human cultural background. It was a miracle that codebreaking was just possible with 1940s digital technology: mathematics and physics really did matter. Mathematics and physics have now made possible almost incredible feats of data manipulation: where it will lead is a question for everyone.