Turing, Alan Mathison (1912–54)

Alan Turing was a mathematical logician who made fundamental contributions to the theory of computation. He developed the concept of an abstract computing device (a ‘Turing machine’) which precisely characterizes the concept of computation, and provided the basis for the practical development of electronic digital computers beginning in the 1940s. He demonstrated both the scope and limitations of computation, proving that some mathematical functions are not computable in principle by such machines.

Turing believed that human behaviour might be understood in terms of computation, and his views inspired contemporary computational theories of mind. He proposed a comparative test for machine intelligence, the ‘Turing test’, in which a human interrogator tries to distinguish a computer from a human by interacting with them only over a teletypewriter. Although the validity of the Turing test is controversial, the test and modifications of it remain influential measures for evaluating artificial intelligence.