In This Article Expand or collapse the "in this article" section Turing Test

  • Introduction
  • Turing’s Life
  • Turing’s Writings on Machine Intelligence
  • Secondary Literature: Edited Collections
  • Secondary Literature: Overviews
  • The Imitation Game
  • Empirical Games
  • Applications
  • The Singularity
  • Searle’s Chinese Room
  • Historical Antecedents to “the Turing Test”

Philosophy Turing Test
Graham Oppy
  • LAST MODIFIED: 25 October 2017
  • DOI: 10.1093/obo/9780195396577-0356


“The Turing Test” is named for the brilliant English logician, mathematician, cryptographer, computer programmer, and computer engineer, Alan Turing (b. 1912–d. 1954). In a seminal paper in Mind entitled “Computing Machinery and Intelligence” (Turing 1950, cited under Turing’s Writings on Machine Intelligence), Turing claimed that, by the end of the 20th century, computers with a storage capacity of 109 could be programmed to play his imitation game so well that an average interrogator would have no more than a 70-percent chance of correctly identifying the computer after five minutes of asking questions. “The Turing Test” is thus a behavioral test for the presence of mind—or thought, or intelligence—in some kinds of putatively minded entities. Very little about “the Turing Test” is uncontroversial. There is dispute about how, exactly, Turing’s imitation game should be understood. There are serious questions about the adequacy of Turing’s replies to certain objections—e.g., the Mathematical Objection, Lady Lovelace’s Objection, and the Argument from the Continuity of the Nervous System—to the claim that computing machines might “do well” in Turing’s imitation game. There is contestation about the significance of the numbers that appear in Turing’s prediction: the date, the storage capacity, the chance of correct identification, and the time allotted to the asking of questions. There is a very extensive philosophical literature that addresses the question whether success in “the Turing Test” provides a sufficient condition for the presence of mind (or thought or intelligence). There is also some philosophical literature that objects to the suggestion that success in “the Turing Test” provides a necessary condition for the presence of mind (or thought or intelligence). There is a much larger literature that considers whether “the Turing Test” is too easy, or too narrow, or too hard, or otherwise harmful and pernicious. There is a significant literature concerned with amendments to, or extensions of, or replacements for, “the Turing Test” (e.g., the Total Turing Test, the Lovelace Test, the Truly Total Turing Test, and so on). There have been numerous attempts to construct computer programs that can “pass” “the Turing Test”; there have been many competitions in which these programs have been tested to see which is the current “champion.” Work on programs that can “pass” “the Turing Test” has had spillover consequences for cyber-security and, in particular, for the use of CAPTCHAs (Completely Automated Public Turing test to tell Computers and Humans Apart). Turing’s prediction—and the hypothesis that it embodies—have important consequences for other large topics in the field of artificial intelligence, including recent discussion of “the Singularity,” and the more established discussion of John Searle’s Chinese Room thought experiment. Finally, there has been discussion of possible historical antecedents for, or anticipations of, “the Turing Test” in the work of Descartes and other early modern philosophers.

Turing’s Life

Turing’s life and work have captured the imagination of a range of artists. There is a well-received 2007 opera, The Turing Test, composed by Julian Wagstaff. There is a similarly well-received 1986 play—subsequently made into a television film—Breaking the Code, written by Hugh Whitemore. And there is a popular 2014 movie, The Imitation Game, directed by Morten Tyldum and reviewed rather negatively by Christian Caryl in the New York Review of Books. Alan Hodges is Turing’s major biographer. Hodges 1983, Hodges 2013, and Hodges 2016 are indispensable resources for anyone interested in Turing’s life. Leavitt 2007 is a useful, though less authoritative, biography of Turing. McCorduck 1979 locates Turing among his peers and gives a splendid account of the people who initiated research into artificial intelligence. The centenary of Turing’s birth was widely celebrated.

  • Hodges, A. Alan Turing: The Enigma. London: Burnett, 1983.

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    A superb biography, and the obvious starting point for anyone wishing to learn about the inner and outer lives of Alan Turing. Hodges is a mathematician and historian of science; the biography does justice to Turing’s work in mathematics, computers, and cryptography, and to his turbulent life and tragic early death. (A second edition, published in 2014, includes discussion of the posthumous royal pardon granted to Alan Turing in 2013.)

  • Hodges, A. “Alan Turing.” In The Stanford Encyclopedia of Philosophy. Edited by Edward N. Zalta. Stanford, CA: Stanford University, 2013.

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    A compact account of Turing’s intellectual biography. Apart from a very brief outline of Turing’s life, it covers the Turing machine and computability, “the logical and the physical,” the uncomputable, building a universal machine, building a brain, machine intelligence, and work Turing left unfinished. It also contains a good list of selected works by Turing, and a useful bibliography of secondary literature.

  • Hodges, A. Alan Turing: The Enigma, 2016.

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    This website is “an electronic extension” of Alan Hodges’ biography of Turing. It includes a section on Turing Sources—scans and transcripts of original documents, archives and photographs, and a complete bibliography of Turing’s papers—and a Scrapbook—informal pages with pictures, links, and additional comments on a wide range of topics including Turing machines, Enigma cryptanalysis, the invention of the computer, “the Turing Test,” and Turing’s personal life. It also contains a bibliography of Hodges’ writings on Turing.

  • Leavitt, D. The Man Who Knew Too Much: Alan Turing and the Invention of the Computer. London: Phoenix, 2007.

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    Hodges says of this work that “it is no ground-breaking book and nor does it do much hoeing or weeding: it is a survey of a field long cultivated by other hands, devoid of new witnesses.” Moreover, Hodges suggests that the major theme—“the gay outsider driven to his death”—is overplayed at the expense of Turing’s contributions to mathematics and science. Nonetheless, this is a perfectly serviceable introduction to Turing’s life, times, and achievement.

  • McCorduck, P. Machines Who Think: A Personal Inquiry into the History and Prospects of Artificial Intelligence. New York: W. H. Freeman, 1979.

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    A fascinating account of the history of research into artificial intelligence. Although the work is mainly focused on the United States—and people such as John McCarthy, Hubert Dreyfus, Edward Feigenbaum, Edward Fredkin, Marvin Minsky, Allen Newell, Herbert Simon, Ray Solomonoff, and Joseph Weizenbaum—it contains an interesting chapter on Turing (and Turing’s arguments with John von Neumann about the possibility of thinking machines).

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