TURING’S WAGER?

Abstract

We examine Turing’s intriguing claim, made in the philosophy journal Mind, that he had created a short computer program of such a nature that it would be impossible “to discover by observation sufficient about it to predict its future behaviour, and this within a reasonable time, say a thousand years” (Turing, 1950, p. 457). A program like this would naturally have cryptographic applications, and we explore how the program would most likely have functioned. Importantly, a myth has recently grown up around this program of Turing’s, namely that it can be used as the basis of an argument—and was so used by Turing—to support the conclusion that it is impossible to infer a detailed mathematical description of the human brain within a practicable timescale. This alleged argument of Turing’s has been dubbed “Turing’s Wager” (Thwaites, Soltan, Wieser, Nimmo-Smith, 2017, p. 3) We demonstrate that this argument—in fact nowhere to be found in Turing’s work—is worthless, since it commits a glaring logical fallacy. “Turing’s Wager” gives no grounds for pessimism about the prospects for understanding and simulating the human brain.

Keywords

• alan turing; turing’s wager
• mechanized encryption
• laws of be- haviour
• unspecifiability of the mind
• brain modelling
• whole-brain simulation
• cipher machines
• enigma
• fish
• tunny
• early computer-based cryptography