A charismatic speaker well known for his clarity and wit, he once delivered a lecture (1994b) giving an account of Gödel's second incompleteness theorem, employing only words of one syllable. At the end of his viva, Hilary Putnam asked him, "And tell us, Mr. Boolos, what does the analytical hierarchy have to do with the real world?" Without hesitating Boolos replied, "It's part of it". An expert on puzzles of all kinds, in 1993 Boolos reached the London Regional Final of The Timescrossword competition. His score was one of the highest ever recorded by an American. He wrote a paper on "The Hardest Logic Puzzle Ever"—one of many puzzles created by Raymond Smullyan.
Boolos coauthored with Richard Jeffrey the first three editions of the classic university text on mathematical logic, Computability and Logic. The book is now in its fifth edition, the last two editions updated by John P. Burgess.
Kurt Gödel wrote the first paper on provability logic, which applies modal logic—the logic of necessity and possibility—to the theory of mathematical proof, but Gödel never developed the subject to any significant extent. Boolos was one of its earliest proponents and pioneers, and he produced the first book-length treatment of it, The Unprovability of Consistency, published in 1979. The solution of a major unsolved problem some years later led to a new treatment, The Logic of Provability, published in 1993. The modal-logical treatment of provability helped demonstrate the "intensionality" of Gödel's Second Incompleteness Theorem, meaning that the theorem's correctness depends on the precise formulation of the provability predicate. These conditions were first identified by David Hilbert and Paul Bernays in their Grundlagen der Arithmetik. The unclear status of the Second Theorem was noted for several decades by logicians such as Georg Kreisel and Leon Henkin, who asked whether the formal sentence expressing "This sentence is provable" (as opposed to the Gödel sentence, "This sentence is not provable") was provable and hence true. Martin Löb showed Henkin's conjecture to be true, as well as identifying an important "reflection" principle also neatly codified using the modal logical approach. Some of the key provability results involving the representation of provability predicates had been obtained earlier using very different methods by Solomon Feferman.
Boolos was an authority on the 19th-century German mathematician and philosopher Gottlob Frege. Boolos proved a conjecture due to Crispin Wright (and also proved, independently, by others), that the system of Frege's Grundgesetze, long thought vitiated by Russell's paradox, could be freed of inconsistency by replacing one of its axioms, the notorious Basic Law V with Hume's Principle. The resulting system has since been the subject of intense work.[citation needed]
1971, "The iterative conception of set," Journal of Philosophy 68: 215–231. Reprinted in Paul Benacerraf and Hilary Putnam, eds.,1984. Philosophy of Mathematics: Selected Readings, 2nd ed. Cambridge Univ. Press: 486–502. LLL
1973, "A note on Evert Willem Beth's theorem," Bulletin de l'Academie Polonaise des Sciences 2: 1–2.
1974, "Arithmetical functions and minimization," Zeitschrift für mathematische Logik und Grundlagen der Mathematik 20: 353–354.
1974a, "Reply to Charles Parsons' 'Sets and classes'." First published in LLL.
1975, "Friedman's 35th problem has an affirmative solution," Notices of the American Mathematical Society 22: A-646.
1975a, "On Kalmar's consistency proof and a generalization of the notion of omega-consistency," Archiv für Mathematische Logik und Grundlagenforschung 17: 3–7.
1985, "1-consistency and the diamond," Notre Dame Journal of Formal Logic 26: 341–347.
1985a, "Nominalist Platonism," The Philosophical Review 94: 327–344. LLL.
1985b, "Reading the Begriffsschrift," Mind 94: 331–344. LLL; FPM: 163–81.
1985c (with Giovanni Sambin), "An incomplete system of modal logic," Journal of Philosophical Logic 14: 351–358.
1986, Review of Yuri Manin, A Course in Mathematical Logic, Journal of Symbolic Logic 51: 829–830.
1986–87, "Saving Frege from contradiction," Proceedings of the Aristotelian Society 87: 137–151. LLL; FPM 438–52.
1987, "The consistency of Frege's Foundations of Arithmetic" in J. J. Thomson, ed., 1987. On Being and Saying: Essays for Richard Cartwright. MIT Press: 3–20. LLL; FPM: 211–233.
1987a, "A curious inference," Journal of Philosophical Logic 16: 1–12. LLL.
1987b, "On notions of provability in provability logic," Abstracts of the 8th International Congress of Logic, Methodology and Philosophy of Science 5: 236–238.
1987c (with Vann McGee), "The degree of the set of sentences of predicate provability logic that are true under every interpretation," Journal of Symbolic Logic 52: 165–171.
1989a, "A new proof of the Gödel incompleteness theorem," Notices of the American Mathematical Society 36: 388–390. LLL. An afterword appeared under the title "A letter from George Boolos," ibid., p. 676. LLL.
1990, "On 'seeing' the truth of the Gödel sentence," Behavioral and Brain Sciences 13: 655–656. LLL.
1990a, Review of Jon Barwise and John Etchemendy, Turing's World and Tarski's World, Journal of Symbolic Logic 55: 370–371.
1990c, "The standard of equality of numbers" in Boolos, G., ed., Meaning and Method: Essays in Honor of Hilary Putnam. Cambridge Univ. Press: 261–278. LLL; FPM: 234–254.
1991, "Zooming down the slippery slope," Nous 25: 695–706. LLL.
1991a (with Giovanni Sambin), "Provability: The emergence of a mathematical modality," Studia Logica 50: 1–23.
1993, "The analytical completeness of Dzhaparidze's polymodal logics," Annals of Pure and Applied Logic 61: 95–111.
1993a, "Whence the contradiction?" Aristotelian Society Supplementary Volume 67: 213–233. LLL.
1994, "1879?" in P. Clark and B. Hale, eds. Reading Putnam. Oxford: Blackwell: 31–48. LLL.
1994a, "The advantages of honest toil over theft," in A. George, ed., Mathematics and Mind. Oxford University Press: 27–44. LLL.
1994b, "Gödel's second incompleteness theorem explained in words of one syllable," Mind 103: 1–3. LLL.
1995, "Frege's theorem and the Peano postulates," Bulletin of Symbolic Logic 1: 317–326. LLL.
1995a, "Introductory note to *1951" in Solomon Feferman et al., eds., Kurt Gödel, Collected Works, vol. 3. Oxford University Press: 290–304. LLL. *1951 is Gödel's 1951 Gibbs lecture, "Some basic theorems on the foundations of mathematics and their implications."
1995b, "Quotational ambiguity" in Leonardi, P., and Santambrogio, M., eds. On Quine. Cambridge University Press: 283–296. LLL
1997a, "Is Hume's principle analytic?" In Richard G. Heck, Jr., ed., Language, Thought, and Logic: Essays in Honour of Michael Dummett. Oxford Univ. Press: 245–61. LLL.
1997b (with Richard Heck), "Die Grundlagen der Arithmetik, §§82–83" in Matthias Schirn, ed., Philosophy of Mathematics Today. Oxford Univ. Press. LLL.
1998, "Gottlob Frege and the Foundations of Arithmetic." First published in LLL. French translation in Mathieu Marion and Alain Voizard eds., 1998. Frege. Logique et philosophie. Montréal and Paris: L'Harmattan: 17–32.
2000, "Must we believe in set theory?" in Gila Sher and Richard Tieszen, eds., Between Logic and Intuition: Essays in Honour of Charles Parsons. Cambridge University Press. LLL.
^Irving H. Anellis, ed. (July 1996). "GEORGE S. BOOLOS". Modern Logic. 6 (3). Project Euclid: 304–310.
^Boolos, George Stephen (1961). A simple proof of Gödel's first incompleteness theorem. Princeton, NJ: Department of Mathematics.
^"Professor George Boolos Dead at 55". MIT News. 29 May 1996.
References
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Peter Simons (1982) "On understanding Lesniewski," History and Philosophy of Logic.
Solomon Feferman (1960) "Arithmetization of metamathematics in a general setting," Fundamentae Mathematica vol. 49, pp. 35–92.
External links
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George Boolos Memorial Web Site[dead link]
Boolos, George (1996). "The Hardest Logic Puzzle Ever" (PDF). The Harvard Review of Philosophy. 6 (1): 62–65. doi:10.5840/harvardreview1996615. Archived from the original (PDF) on 22 June 2012.