Wittgenstein’s Philosophies of Mathematics

Abstract

Wittgenstein’s philosophy of mathematics has long been notorious. Part of the problem is that it has not been recognized that Wittgenstein, in fact, had two chief post-Tractatus conceptions of mathematics. I have labelled these the calculus conception and the language-game conception. The calculus conception forms a distinct middle period. The goal of my article is to provide a new framework for examining Wittgenstein’s philosophies of mathematics and the evolution of his career as a whole. I posit the Hardyian Picture, modelled on the Augustinian Picture, to provide a structure for Wittgenstein’s work on the philosophy of mathematics. Wittgenstein’s calculus period has not been properly recognized, so I give a detailed account of the tenets of that stage in Wittgenstein’s career. Wittgenstein’s notorious remarks on contradiction are the test case for my theory of his transition. I show that the bizarreness of those remarks is largely due to the calculus conception, but that Wittgenstein’s later language-game account of mathematics keeps the rejection of the Hardyian Picture while correcting the calculus conception’s mistakes.

The following abbreviations are used in this article to refer to Wittgenstein’s works: WWK: Ludwig Wittgenstein and the Vienna Circle: Conversations Recorded by Friedrich Waismann, ed. B. F. McGuinness, trans. J. Schulte and B. F. McGuinness, Oxford: Basil Blackwell, 1979; CAM I: Wittgenstein’s Lectures: Cambridge, 1930–32, ed. D. Lee, Chicago: University of Chicago Press, 1982; CAM II: Wittgenstein’s Lectures: Cambridge, 1932–35; ed. A. Ambrose, Chicago: University of Chicago Press, 1982; PG: Philosophical Grammar, ed. R. Rhees, trans. A. Kenny, Oxford: Basil Blackwell, 1974; BIB: The Blue and Brown Books, Oxford: Basil Blackwell, 1958; LFM: Wittgenstein’s Lectures on the Foundations of Mathematics: Cambridge, 1939, ed. C. Diamond, Ithaca: Cornell University Press, 1976; RFM: Remarks on the Foundations of Mathematics, ed. G. H. von Wright, R. Rhees, G. E. M. Anscombe, trans. G. E. M. Anscombe, revised ed., Cambridge: MIT Press, 1978; PI: Philosophical Investigations, ed. G. E. M. Anscombe, R. Rhees, trans. G. E. M. Anscombe, New York: Macmillan Company, 1953; Z: Zettel, ed. G. E. M. Anscombe, G. H. von Wright, trans. G. E. M. Anscombe, Berkeley and Los Angeles: University of California Press, 1970.

References to PI and Z are to remark number; references to RFM are to part number (Roman numerals) and remark number (Arabic numerals); and references to the other works are to page numbers. As the evolutionary nature of Wittgenstein’s work is an important theme of this article, following the abbreviation for the book in the text I have put in brackets the date of the book or the part of the book from which the quotation comes.