The Man Who Knew Too Much

With a subject as complex and influential as Alan Turing, how could this biography fail to be fascinating? The premise of the book is an examination of Turing as an outsider, someone prone to working alone, a trait which helped him come up with outside-the-box ideas of universal machines. It explores Turing’s deep-seated sense of isolation and to what extent it was caused by his position as an unashamed but closeted gay man and how he feared his homosexuality would be used to discredit his ideas. As Turing once wrote in a syllogism:

Turing believes machines think Turing lies with men Therefore machines do not think

The heart of the book is taken up with Turing’s creation of the “Turing machine” or “universal machine”, which he thought up in response to the Entscheidungsproblem. Also called the decision problem, it posed the question: Is there an algorithim that can be found which will determine whether any other formula is true or false? In order to stress that the size and complexity of the hypothetical algorithim did not matter, Turing used the metaphor of a machine capable of spending years on the problem. With this metaphor established in loving detail, Turing set out to prove that no such algorithim can exist. That he was not the first to disprove the Entscheidungsproblem is irrelevant. What matters was his conceptualization of the universal machine, making him (arguably) the founding father of the modern-day computer.

Later in life, as these “thinking machines” began to be built, Turing took a step further, arguing for artificial intelligence. Here is where the book truly shines, as it draws parallels between Turing’s fervent support for artificial intelligence and his position a gay man in a homophobic society. Turing’s critics would frequently cite things a machine cannot do as things which make a machine not a man, for instance, “be kind, resourceful, beautiful, friendly; have a sense of humor; tell right from wrong; fall in love, enjoy strawberries and cream” (p. 251). Obviously, these traits are not necessary to be human (I, for one, do not really like strawberries and cream) and the insistence of the general community that thinking machines (even the exponentially more complex machines of the future) be excluded from the definition of mankind deeply bothered Turing.

Leavitt does an admirable job of explaining the mathematics behind Turing’s work, although of course his treatments must be superficial. Still, they are treated with enough thoroughness to render the subsequent logical and rhetorical battles waged by Turing and his peers quite understandable. The book is also filled with interesting tidbits. For instance, apparently the word “computer” used to apply to the people, usually women, who slowly and doggedly performed the complex calculations given to them by mathematicians and engineers. Also, when Turing was involved in code-breaking for the British government during WWII, they would often set landmines in specific places so that they could look for certain words (known as “cribs”) in the German communications, which would help them break the cipher.

The last section is short and incredibly saddening. It details the end of Turing’s life when, still a productive if rather notorious mathematician, he was arrested for being gay and forced to undergo a series of estrogen treatments. Shortly thereafter he committed suicide. The method of his suicide was particularly haunting. Turing had seen the Disney movie Snow White when it came out in theaters and was captured by it, going back to see it six more times. He killed himself by eating an apple dipped in cyanide. Turing was too intelligent and romantic a man to not have seen the symbolism in his own death. As Leavitt writes, “Today the apple continues to fascinate. Much is made of its metaphorical implications (apple of death, apple of knowledge - but too much knowledge?). A rumor circulates on the internet that the apple that is the logo of Apple Computers is a nod to Turing. The company denies any connection; on the contrary, they insist, its apple alludes to Newton. But then why is there a bite taken out of it?” (p. 280)

There must be other worthy biographies of Alan Turing, and more thorough examinations of his theories and accomplishments, however this story of Turing, his ostracization, and his fight on behalf of the lonely and as yet unrealized AI is not to be missed.

(Originally posted June 2007.)