Sir Michael A.E. Dummett

Sir Michael A.E. Dummett (born June 27, 1925, London, England—died December 27, 2011, Oxford) was an English philosopher who did influential work in the philosophy of language, metaphysics, logic, the philosophy of mathematics, and the history of analytic philosophy. He was also one of the foremost expositors of the work of the German mathematical logician Gottlob Frege (1848–1925). Dummett was known chiefly for his defense of antirealism (see realism) and his attempt to explicate sentence meaning in terms of “assertibility conditions” rather than truth conditions.

Dummett attended Sandroyd School and Winchester College and later served in the British army (1943–47). In 1950 he received a B.A. degree in philosophy, politics, and economics at Christ Church College, Oxford, and was awarded a prize fellowship in philosophy at Oxford’s All Souls College. He was subsequently a research fellow at All Souls from 1957, emeritus fellow from 1979, and Wykeham Professor of Logic at Oxford from 1979 until his retirement in 1992. Throughout his career he held numerous visiting professorships, including those at the University of Birmingham, England, the University of Ghana; Stanford and Princeton universities in the United States; and the University of Münster, Germany. Dummett was knighted in 1999 for his philosophical work and his decades-long efforts to combat racism in British society.

According to Dummett, metaphysical realism is equivalent to the view that sentences are true or false independently of whether it is possible (even in principle) to recognize them as such. Mathematical realism, for example, implies that the Goldbach conjecture (every even counting number greater than 2 is the sum of two primes) is either true or false, even though there is no known method for deciding which. Dummett pressed two main challenges to realism thus construed: (1) to explain how humans could come to understand statements which are unrecognizably true, given that human linguistic training necessarily proceeds in terms of publicly accessible and recognizable aspects of use, and (2) to explain how such an alleged understanding could be manifested or displayed.

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Philosophy 101

Although Dummett did not endorse verificationism (the view that a statement is cognitively meaningful only if it is possible in principle to verify it), he argued for a position that connects truth more closely than the realist does with evidence or with grounds for belief. Thus, according to Dummett, the meanings of sentences must be explicated not in terms of potentially evidence-transcendent truth-conditions but by reference to conditions—such as those under which a statement counts as correctly asserted—that can be recognized to obtain whenever they do.

As he emphasized, the adoption of such an antirealist view of truth carries significant implications outside the theory of meaning, especially for logic and hence mathematics. In particular, logical principles such as the law of excluded middle (for every proposition p, either p or its negation, not-p, is true, there being no “middle” true proposition between them) can no longer be justified if a strongly realist conception of truth is replaced by an antirealist one that restricts what is true to what can in principle be known. There is no guarantee, for example, that for an arbitrary mathematical proposition p, either p or not-p can be proved. Because many important theorems in classical mathematics depend for their proof upon the principles affected, large parts of classical mathematics are called into question. In this way, Dummett’s antirealism about truth and meaning lended support to revisionary constructivist approaches to mathematics, such as intuitionism.

Dummett’s major philosophical works include Frege: Philosophy of Language (1973), Truth and Other Enigmas (1978), The Logical Basis of Metaphysics (1991), The Seas of Language (1993), The Origins of Analytical Philosophy (1993), Truth and the Past (2004), and Thought and Reality (2006). Dummett also wrote several works on tarot cards and games, on which he was an internationally recognized authority.