John Lucas (philosopher)

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John Lucas

John Lucas.png
Born(1929-06-18)18 June 1929
Guildford, England
Died5 April 2020(2020-04-05) (aged 90)
Somerset, England
Alma materBalliol College, Oxford
Notable work
"Minds, Machines and Gödel"
EraContemporary philosophy
RegionWestern philosophy
SchoolAnalytic philosophy
InstitutionsMerton College, Oxford
Academic advisorsR. M. Hare
Main interests
Logic, philosophy of mathematics, philosophy of mind
Notable ideas
Gödelian argument
Penrose–Lucas argument4

John Randolph Lucas FBA (18 June 1929 – 5 April 2020)[1] was a British philosopher.


Lucas was educated at Winchester College and then, as a pupil of R.M. Hare, among others, at Balliol College, Oxford.[2] He studied first mathematics, then Greats (Greek, Latin, Philosophy and Ancient History), obtaining first class honours in both. He sat for Finals in 1951, and took his MA in 1954. He spent the 1957–58 academic year at Princeton University, studying mathematics and logic. For 36 years, until his 1996 retirement, he was a Fellow and Tutor of Merton College, Oxford, and he remained an emeritus member of the University Faculty of Philosophy. He was a Fellow of the British Academy.[3]

Lucas is perhaps best known for his paper "Minds, Machines and Gödel," arguing that an automaton cannot represent a human mathematician, attempting to refute computationalism.

An author with diverse teaching and research interests, Lucas wrote on the philosophy of mathematics, especially the implications of Gödel's incompleteness theorem, the philosophy of mind, free will and determinism, the philosophy of science including one book on physics co-authored with Peter E. Hodgson, causality, political philosophy, ethics and business ethics, and the philosophy of religion.

The son of a Church of England clergyman, and an Anglican himself, Lucas described himself as "a dyed-in-the-wool traditional Englishman." He had four children (Edward, Helen, Richard and Deborah) with Morar Portal, among them Edward Lucas, a former journalist at The Economist.

In addition to his philosophical career, Lucas had a practical interest in business ethics. He helped found the Oxford Consumers' Group,[4] and was its first chairman in 1961–3, serving again in 1965.

Philosophical contributions[edit]

Free will[edit]

Lucas (1961) began a lengthy and heated debate over the implications of Gödel's incompleteness theorems for the anthropic mechanism thesis, by arguing that:[5]

  1. Determinism ↔ For any human h there exists at least one (deterministic) logical system L(h) which reliably predicts h's actions in all circumstances.
  2. For any logical system L a sufficiently skilled mathematical logician (equipped with a sufficiently powerful computer if necessary) can construct some statements T(L) which are true but unprovable in L. (This follows from Gödel's first theorem.)
  3. If a human m is a sufficiently skillful mathematical logician (equipped with a sufficiently powerful computer if necessary) then if m is given L(m), he or she can construct T(L(m)) and determine that they are true—which L(m) cannot do.
  4. Hence L(m) does not reliably predict m's actions in all circumstances.
  5. Hence m has free will.
  6. It is implausible that the qualitative difference between mathematical logicians and the rest of the population is such that the former have free will and the latter do not.

His argument was strengthened by the discovery by Hava Siegelmann in the 1990s that sufficiently complex analogue recurrent neural networks are more powerful than Turing Machines.[6]

Space, time and causality[edit]

Lucas wrote several books on the philosophy of science and space-time (see below). In A treatise on time and space[7] he introduced a transcendental derivation of the Lorenz Transformations based on Red and Blue exchanging messages (in Russian and Greek respectively) from their respective frames of reference which demonstrates how these can be derived from a minimal set of philosophical assumptions.

In The Future Lucas gives a detailed analysis of tenses and time, arguing that "the Block universe gives a deeply inadequate view of time. It fails to account for the passage of time, the pre-eminence of the present, the directedness of time and the difference between the future and the past"[8] and in favour of a tree structure in which there is only one past or present (at any given point in spacetime) but a large number of possible futures. "We are by our own decisions in the face of other men's actions and chance circumstances weaving the web of history on the loom of natural necessity"[9]




  1. ^ "Lucas, John Randolph, FBA - Deaths Announcements - Telegraph Announcements". Retrieved 7 April 2020.
  2. ^ Lucas, John (23 December 2002). "Balliol College - History - Past Members - Richard Hare - A Memoir". Archived from the original on 23 December 2002. Retrieved 11 May 2019.
  3. ^ "Mr John Lucas". The British Academy. Retrieved 11 May 2019.
  4. ^ Oxford Consumers' Group Archived 30 August 2003 at the Wayback Machine
  5. ^ J.R. Lucas, "The Gödelian Argument"
  6. ^ H.T. Siegelmann, "Computation Beyond the Turing Limit," Science, 238(28), April 1995: 632–637
  7. ^ John Randolph Lucas (1 January 1973). A treatise on time and space. Methien &CO Ltd. p. 332. Archived from the original on 26 January 2020.
  8. ^ The Future (1989), p. 8.
  9. ^ The Future (1989), p. 4.

Further reading[edit]