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FORMALIZATION, PRIMITIVE CONCEPTS, AND PURITY

Published online by Cambridge University Press:  19 September 2012

JOHN T. BALDWIN*
Affiliation:
Professor emeritus, University of Illinois at Chicago
*
*DEPARTMENT OF MATHEMATICS, STATISTICS, AND COMPUTER SCIENCE UNIVERSITY OF ILLINOIS AT CHICAGO MIC 249, 851 S. MORGAN STREET CHICAGO, IL 60607. E-mail: [email protected]

Abstract

We emphasize the role of the choice of vocabulary in formalization of a mathematical area and remark that this is a particular preoccupation of logicians. We use this framework to discuss Kennedy’s notion of ‘formalism freeness’ in the context of various schools in model theory. Then we clarify some of the mathematical issues in recent discussions of purity in the proof of the Desargues proposition. We note that the conclusion of ‘spatial content’ from the Desargues proposition involves arguments which are algebraic and even metamathematical. Hilbert showed that the Desargues proposition implies the coordinatizing ring is associative, which in turn implies the existence of a three-dimensional geometry in which the given plane can be embedded. With W. Howard we give a new proof, removing Hilbert’s ‘detour’ through algebra, of the ‘geometric’ embedding theorem.

Finally, our investigation of purity leads to the conclusion that even the introduction of explicit definitions in a proof can violate purity. We argue that although both involve explicit definition, our proof of the embedding theorem is pure while Hilbert’s is not. Thus the determination of whether an argument is pure turns on the content of the particular proof. Moreover, formalizing the situation does not provide a tool for characterizing purity.

Type
Research Article
Copyright
Copyright © Association for Symbolic Logic 2012

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References

BIBLIOGRAPHY

Arana, A. (2008a). Logical and semantic purity. Protosociology, 25, 3648.Google Scholar
Arana, A. (2008b). On formally measuring and eliminating extraneous notions in proofs. Philosophia Mathematica, 3, 119.Google Scholar
Arana, A. (2011). Purity in arithmetic: Some formal and informal issues. To appear.Google Scholar
Arana, A., & Mancosu, P. (2012). On the relationship between plane and solid geometry. Review of Symbolic Logic, 5, 294353.Google Scholar
Artin, E. (1957). Geometric Algebra. New York: Interscience.Google Scholar
Baldwin, J. T. (1994). An almost strongly minimal non-Desarguesian projective plane. Transactions of the American Mathematical Society, 342, 695711.CrossRefGoogle Scholar
Baldwin, J. T. (1995). Some projective planes of Lenz Barlotti class I. Proceedings of the American Mathematical Society, 123, 251256.Google Scholar
Baldwin, J. T. (2009). Categoricity. Number 51 in University Lecture Notes. Providence, RI: American Mathematical Society. Available from: http://www.math.uic.edu/~jbaldwin.Google Scholar
Barwise, J., & Feferman, S. editors. (1985). Model-Theoretic Logics. Heidelberg, Germany: Springer-Verlag.Google Scholar
Burgess, J. P. (2010). Putting structuralism in its place. To appear.Google Scholar
Cronheim, A. (1953). A proof of Hessenberg’s theorem. Proceedings of the American Mathematical Society, 4, 219221.Google Scholar
Dembowski, P. (1977). Finite Geometries. Springer-Verlag.Google Scholar
Detlefsen, M., & Arana, A. (2011). Purity of methods. Philosophers Imprint, 11, 120.Google Scholar
Educational Development Corporation. (2009). CME Algebra I. Boston, MA: Pearson. EDC: Educational Development Corporation, Newton, MA.Google Scholar
Ehrlich, P. (2001). Number systems with simplicity hierarchies: A generalization of conway’s theory of surreal numbers. The Journal of Symbolic Logic, 66, 12311258.Google Scholar
Eklof, P. (1976). Whitehead’s problem is undecidable. American Mathematical Monthly, 83, 775788.Google Scholar
Euclid. (1956). Euclid’s Elements. New York: Dover. In three volumes, translated by T.L. Heath; first edition 1908.Google Scholar
Feferman, S. (2008). Tarski’s conceptual analysis of semantical notions. In Patterson, D., editor. New Essays on Tarski and Philosophy. Oxford, UK: Oxford University Press.Google Scholar
Givant, S., & Tarski, A. (1999). Tarski’s system of geometry. Bulletin of Symbolic Logic, 5, 175214.Google Scholar
Gödel, K. (1946). Remarks before the Princeton bicentennial conference of problems in mathematics. In Feferman, S. et al. ., editors. Kurt Gödel: Collected Works, Vol. 1. New York: Oxford University Press, 1990. 1929 PhD. thesis reprinted.Google Scholar
Grätzer, G. (1968). Universal Algebra. Princeton, NJ: Van Nostrand.Google Scholar
Hallett, M. (2008). Reflections on the purity of method in Hilbert’s Grundlagen der Geometrie. In Mancosu, P., editor. The Philosophy of Mathematical Practice. Oxford, UK: Oxford University Press, pp. 198256.CrossRefGoogle Scholar
Hartshorne, R. (1967). Geometry: Foundations of Projective Geometry. New York: W.A. Benjamin.Google Scholar
Henderson, D., & Taimina, D. (2005). How to use history to clarify common confusions in geometry. In Shell-Gellasch, A., and Jardine, D., editors. From Calculus to Computers, Vol. 68 of MAA Math Notes. Providence, RI: Mathematical Association of America, pp. 5774.Google Scholar
Hessenberg, G. (1905). Beweis des desarguesschen satzes aus dem pascalschen. Mathematische Annalen, 61, 161172.Google Scholar
Heyting, A. (1963). Axiomatic Projective Geometry. New York: John Wiley & Sons.Google Scholar
Hilbert, D. (1971). Foundations of Geometry. Lasalles, IL: Open Court Publishers. Original German publication 1899: translation from tenth edition, Bernays 1968.Google Scholar
Hilbert, D. (2004). In Hilbert, and Mayer, , editors. David Hilbert’s Lectures on the Foundations of Geometry 1891-1902. Heidelberg, Germany: Springer, pp. xviii + 665.Google Scholar
Hodges, W. (1987). What is a structure theory? Bulletin of the London Mathematics Society, 19, 209237.CrossRefGoogle Scholar
Hrushovski, E., & Zilber, B. (1993). Zariski geometries. Bulletin of the American Mathematical Society, 28, 315324.Google Scholar
Hughes, D. R., & Piper, F. C. (1973). Projective Planes. Heidelberg, Germany: Springer-Verlag.Google Scholar
Jech, T. (1978). Set Theory, Vol. 79 of Pure and Applied Mathematics. New York: Academic Press.Google Scholar
Keisler, H. J. (1960). Theory of models with generalized atomic formulas. The Journal of Symbolic Logic, 25, 125.Google Scholar
Kennedy, J. (To appear). On formalism freeness.Google Scholar
Kirby, J. (2008). Abstract Elementary Categories. Available from: http://www.uea.ac.uk/~ccf09tku/pdf/aecats.pdf.Google Scholar
Kirby, J. (2010). On quasiminimal excellent classes. Journal of Symbolic Logic, 75, 551564. Available from: http://arxiv.org/PS_cache/arxiv/pdf/0707/0707.4496v3.pdf.Google Scholar
Lang, S. (1964). Algebraic Geometry. New York: Interscience.Google Scholar
Levi, F. W. (1939). On a fundamental theorem of geometry. Journal of the Indian Mathematical Society, 34, 8292.Google Scholar
Lieberman, M. (2011). Category-theoretic aspects of abstract elementary classes. Annals of Pure and Applied Logic, 162(11), 903915.Google Scholar
Manders, K. (2008). Diagram-based geometric practice. In Mancosu, P., editor. The Philosophy of Mathematical Practice. Oxford, UK: Oxford University Press, pp. 6579.Google Scholar
Marker, D. (2002). Model Theory: An introduction. Heidelberg, Germany: Springer-Verlag.Google Scholar
Morley, M. (1965a). Categoricity in power. Transactions of the American Mathematical Society, 114, 514538.Google Scholar
Morley, M. (1965b). Omitting classes of elements. In Addison, , Henkin, , Tarski, , editors. The Theory of Models. Amsterdam: North-Holland, pp. 265273.Google Scholar
Pambuccian, V. (2001). A methodologically pure proof of a convex geometry problem. Beiträge zur Algebra und Geometrie, Contributions to Algebra and Geometry, 42, 40406.Google Scholar
Pambuccian, V. (2005). Euclidean geometry problems rephrased in terms of midpoints and point-reflections. Elemente der Mathematik, 60, 1924.Google Scholar
Pambuccian, V. (2009). A reverse analysis of the Sylvester-Gallai theorem. Notre Dame Journal of Formal Logic, 50, 245259.Google Scholar
Pierce, D. (2011). Numbers. Available from: http://metu.edu.tr/∼dpierce/Mathematics/Numbers.Google Scholar
Robinson, G. d. B. (1959). Foundations of Geometry. Toronto, Canada: Toronto Press.Google Scholar
Shelah, S. (1983). Classification theory for nonelementary classes. I. the number of uncountable models of part A. Israel Journal of Mathematics, 46(3), 212240. paper 87a.Google Scholar
Shelah, S. (2009). Classification Theory for Abstract Elementary Classes. Studies in Logic. College Publications. Available from: http://www.collegepublications.co.uk, 2009. Binds together papers 88r, 600, 705, 734 with introduction E53.Google Scholar
Shoenfield, J. (1967). Mathematical Logic. Addison-Wesley.Google Scholar
Smith, J. T. (2010). Definitions and non-definability in geometry. American Mathematical Monthly, 117, 475489.Google Scholar
Smullyan, R. M. (1961). Theory of Formal Systems. Princeton, NJ: Princeton University Press.Google Scholar
Sobociski, B. (1955). On well-constructed axiom systems. Polish Society of Arts and Sciences Abroad, 112.Google Scholar
Spivak, M. (1980). Calculus. Houston, TX: Publish or Perish Press.Google Scholar
Suppes, P. (1956). Introduction to Logic. New York: Van Nostrand.Google Scholar
Tarski, A. (1931). Sur les ensemble définissable de nombres réels I. Fundamenta Mathematica, 17, 210239.Google Scholar
Tarski, A. (1952). Some notions and methods on the borderline of algebra and metamathematics. In Proceedings of the International Congress of Mathematicians, Cambridge, Massachusetts, U.S.A., August 30-September 6, 1950, Vol. 1. Providence, RI: American Mathematical Society, pp. 705720.Google Scholar
Tarski, A. (1954). Contributions to the theory of models, I and II. Indagationes Mathematicae, 16, 572582.Google Scholar
Urbanik, R., & Hämäri, K. S. (2012). Busting a Myth about Leniewski and Definitions. History and Philosophy of Logic, 33, 159189.Google Scholar
van den Dries, L. (1986). A generalization of the Tarski-Seidenberg theorem, and some nondefinability results. Bulletin Of The American Mathematical Society, 15, 189193.CrossRefGoogle Scholar
van den Dries, L. (1999). Tame Topology and O-Minimal Structures. London Mathematical Society Lecture Note Series, 248.Google Scholar
Vaught, R. L. (1986). Alfred Tarski’s work in model theory. Journal of Symbolic Logic, 51, 869882.Google Scholar
Vis, T. (Unpublished notes). Desargues Theorem. Unpublished notes. Available from: http://math.ucdenver.edu/~tvis/Teaching/4220spring09/Notes/Desargues.pdf.Google Scholar
Zilber, B. I. (2005). A categoricity theorem for quasiminimal excellent classes. In Logic and its Applications, Contemporary Mathematics. Providence, RI: AMS, pp. 297306.CrossRefGoogle Scholar
Zilber, B. I. (2010). Zariski Geometries, Geometry from the Logician’s Point of View. Cambridge, UK: London Mathematical Society; Cambridge University Press.Google Scholar