Lauener Foundation for Analytical Philosophy
Thursday 27 May 2010
4th International Lauener Symposium
on Analytical Philosophy
In Honour of Professor Sir Michael Dummett
Dr. Daniel Isaacson
(University of Oxford)
Theories of Meaning, Realist and Anti-Realist
Understanding the meaning of a declarative sentence is knowing what that sentence can be used to say, i.e. that things (referred to by words or symbols in the sentence) are thus and so (expressed by words or symbols in the sentence). If those things are thus and so, the sentence is true; otherwise false. This observation points to a prima facie connection between meaning and truth. For Michael Dummett, the connection is via knowing how one could go about determining whether or not the truth conditions for that sentence obtain. This dependence of truth on justification is anti-realist, as against a realist conception of truth independent of our capacities to determine what’s true. Dummett has articulated and developed his justificationist conception of meaning over the past fifty years, beginning with his seminal paper "Truth", published in 1959. Among the accomplishments of Dummett’s anti-realist programme is a new, intersubjective basis for intuitionistic mathematics and logic, supplanting Brouwer’s solipsistic ideology. This construal of intuitionism is of importance for the development and understanding of intuitionististic mathematics and logic, and of importance for philosophy of language in providing anti-realist theories of meaning for languages of mathematics. It also brings into sharp relief the revisionist nature of Dummett’s anti-realism, providing in this case a normative rather than a descriptive understanding of the nature of mathematics, with the apparent outcome that intuitionistic mathematics is how mathematics should be done, as opposed to being a way in which mathematicians may choose to do mathematics.
In this lecture I shall consider Dummett’s anti-realist account of the connection between truth and meaning in its relation to realist accounts that go back to Frege and, in the period in which Dummett has developed his understanding of these issues, have been most strongly pursued by Donald Davidson. I shall argue that accounts of the meanings of declarative sentences given by bivalent truth conditions are too thin to be practically or philosophically fruitful and that a justificationist account offers more. At the same time, I shall express disquiet at revisionism as an outcome of justificationist accounts of meaning.