Alan Turing Quotes

Alan Turing on Freedom

• “The Exclusion Principle is laid down purely for the benefit of the electrons themselves, who might be corrupted (and become dragons or demons) if allowed to associate too freely.”

  Epigram to Robin Gandy (1954).

Alan Turing on God

• “Science is a differential equation . Religion is a boundary condition .”

  Epigram to Robin Gandy (1954); reprinted in Andrew Hodges, Alan Turing: the Enigma (Vintage edition 1992), p. 513.

Alan Turing on Justice

• “The machine may also change the square which is being scanned, but only by shifting it one place to right or left.”

  On Computable Numbers, with an Application to the Entscheidungsproblem (1936)

• “Some of the symbols written down will form the sequence of figures which is the decimal of the real number... being computed. The others are just rough notes to "assist the memory ". ...[O]nly ...these rough notes ...will be liable to erasure.”

  On Computable Numbers, with an Application to the Entscheidungsproblem (1936)

Alan Turing on Knowledge

• “Mathematical reasoning may be regarded rather schematically as the exercise of a combination of two facilities, which we may call intuition and ingenuity . The activity of the intuition consists in making spontaneous judgements which are not the result of conscious trains of reasoning... The exercise of ingenuity in mathematics consists in aiding the intuition through suitable arrangements of prop”

  Systems of Logic Based on Ordinals," section 11: The purpose of ordinal logics (1938), published in Proceedings of the London Mathematical Society, series 2, vol. 45 (1939)

• “Instruction tables will have to be made up by mathematicians with computing experience and perhaps a certain puzzle-solving ability. There need be no real danger of it ever becoming a drudge, for any processes that are quite mechanical may be turned over to the machine itself.”

  Proposed Electronic Calculator" (1946), a report for National Physical Laboratory, Teddington; published in A. M. Turing's ACE Report of 1946 and Other Papers (1986), edited by B. E. Carpenter and R. W. Doran, and in The Collected Works of A. M. Turing (1992), edited by D. C. Ince, Vol. 3.

• “A man provided with paper, pencil, and rubber, and subject to strict discipline, is in effect a universal machine .”

  Intelligent Machinery: A Report by A. M. Turing," (Summer 1948), submitted to the National Physical Laboratory (1948) and published in Key Papers: Cybernetics, ed. C. R. Evans and A. D. J. Robertson (1968) and, in variant form, in Machine Intelligence 5, ed. B. Meltzer and D. Michie (1969).

• “Intelligent Machinery." This passage was one of the epigraphs to Cryptonomicon , the influential novel by Neal Stephenson , in which Turing was a fictionalized character. It shared a page with a quote from Imelda Marcos.”

  There is a remarkably close parallel between the problems of the physicist and those of the cryptographer. The system on which a message is enciphered corresponds to the laws of the universe, the intercepted messages to the evidence available, the keys for a day or a message to important constants which have to be determined. The correspondence is very close, but the subject matter of cryptography

• “This is only a foretaste of what is to come, and only the shadow of what is going to be. We have to have some experience with the machine before we really know its capabilities. It may take years before we settle down to the new possibilities, but I do not see why it should not enter any one of the fields normally covered by the human intellect, and eventually compete on equal terms.”

  The Mechanical Brain. Answer Found to 300 Year Old Problem' The Times newspaper, 11 June 1949 page 4 column 5. | The sentence in bold appears on the latest British £50 bank note featuring Alan Turing which was released on 23 June 2021 on what would have been his 109th birthday.

• “The Mechanical Brain. Answer Found to 300 Year Old Problem' The Times newspaper, 11 June 1949 page 4 column 5.”

  This is only a foretaste of what is to come, and only the shadow of what is going to be. We have to have some experience with the machine before we really know its capabilities. It may take years before we settle down to the new possibilities, but I do not see why it should not enter any one of the fields normally covered by the human intellect, and eventually compete on equal terms.

Read all Alan Turing quotes on Knowledge

Alan Turing on Mind

• Attributed to Alan Turing:

  “Can machines think?”

• Attributed to Alan Turing:

  “A computer would deserve to be called intelligent if it could deceive a human into believing that it was human.”

• “Mathematical reasoning is the exercise of a combination of two faculties: intuition and ingenuity.”

  Systems of Logic Based on Ordinals," section 11: The purpose of ordinal logics (1938), published in Proceedings of the London Mathematical Society, series 2, vol. 45 (1939) | In a footnote to the first sentence, Turing added: "We are leaving out of account that most important faculty which distinguishes topics of interest from others; in fact, we are regarding the function of the mathematician as

• “May not machines carry out something which ought to be described as thinking but which is very different from what a man does?”

  Computing Machinery and Intelligence (1950)

• “I believe that at the end of the century the use of words and general educated opinion will have altered so much that one will be able to speak of machines thinking without expecting to be contradicted.”

  Computing Machinery and Intelligence (1950) | p. 442.

• “'Can digital computers think?'. Talk broadcast on BBC Third Programme, 15 May 1951.”

  'Can digital computers think?' (1951)

Read all Alan Turing quotes on Mind

Alan Turing on Nature

• “Proposed Electronic Calculator" (1946), a report for National Physical Laboratory, Teddington; published in A. M. Turing's ACE Report of 1946 and Other Papers (1986), edited by B. E. Carpenter and R. W. Doran, and in The Collected Works of A. M. Turing (1992), edited by D. C. Ince, Vol. 3.”

  Instruction tables will have to be made up by mathematicians with computing experience and perhaps a certain puzzle-solving ability. There need be no real danger of it ever becoming a drudge, for any processes that are quite mechanical may be turned over to the machine itself.

• “Intelligent Machinery: A Report by A. M. Turing," (Summer 1948), submitted to the National Physical Laboratory (1948) and published in Key Papers: Cybernetics, ed. C. R. Evans and A. D. J. Robertson (1968) and, in variant form, in Machine Intelligence 5, ed. B. Meltzer and D. Michie (1969).”

  A man provided with paper, pencil, and rubber, and subject to strict discipline, is in effect a universal machine .

• “There is a remarkably close parallel between the problems of the physicist and those of the cryptographer. The system on which a message is enciphered corresponds to the laws of the universe, the intercepted messages to the evidence available, the keys for a day or a message to important constants which have to be determined. The correspondence is very close, but the subject matter of cryptography is very easily dealt with by discrete machinery, physics not so easily.”

  Intelligent Machinery." This passage was one of the epigraphs to Cryptonomicon , the influential novel by Neal Stephenson , in which Turing was a fictionalized character. It shared a page with a quote from Imelda Marcos.

Read all Alan Turing quotes on Nature

Alan Turing on Time

• “We can only see a short distance ahead, but we can see plenty there that needs to be done.”

  p. 460.

• “We are not asking whether all digital computers would do well in the game nor whether the computers at present available would do well, but whether there are imaginable computers which would do well.”

  Computing Machinery and Intelligence (1950)

Alan Turing on Truth

• “In a footnote to the first sentence, Turing added: "We are leaving out of account that most important faculty which distinguishes topics of interest from others; in fact, we are regarding the function of the mathematician as simply to determine the truth or falsity of propositions.”

  Mathematical reasoning may be regarded rather schematically as the exercise of a combination of two facilities, which we may call intuition and ingenuity . The activity of the intuition consists in making spontaneous judgements which are not the result of conscious trains of reasoning... The exercise of ingenuity in mathematics consists in aiding the intuition through suitable arrangements of prop

Alan Turing on Virtue

• Attributed to Alan Turing:

  “Sometimes it is the people no one imagines anything of who do the things that no one can imagine.”