Professor Sir Michael Dummett

Logic, language and mathematics were his chief philosophical preoccupations. He was particularly interested in the work of Gottlob Frege (1848-1925), a German mathematician who tried, but ultimately failed, to demonstrate that formal logic could govern all mathematical truths.

In his book, Frege: Philosophy of Mathematics (1991), Dummett attempted to pinpoint precisely where the German had gone wrong, and in the course of his analysis he argued that Frege’s work had two significant by-products for philosophy. First, Frege had invented a new formal language for logic in which, for example, it is possible to describe the difference between the phrase “everybody loves somebody”, and the phrase “there is somebody whom everybody loves”, and to demonstrate clearly how different conclusions can be derived from each of these propositions. Second, Dummett suggested, Frege’s theses about the nature of logic opened up a whole new field – the philosophy of language, through which philosophers might account for thought through an analysis of grammar and semantics.

As well as his work on Frege, Dummett was known for his struggle to resolve the argument between what he termed “realist” philosophers and “anti-realists” (idealists, nominalists etc), who disagree about the logical principles they apply to propositions that are under dispute. For Dummett, the championing of anti-realism meant a rejection of the realist principle of bivalence — the idea that any sentence which attempts to make an assertion must be either true or false. Dummett held that this was not the case for sentences that discuss certain subjects — for example, mathematics.

In particular, Dummett argued that metaphysical debates – such as whether unicorns are real – are properly understood as debates about logical laws and the nature of truth. He delivered his most complete statement of the nature of such metaphysical debates, and the means by which they can be resolved, in The Logical Basis of Metaphysics (1991). Thought and Reality (2006) was a further disquisition on anti-realism.

Though he influenced a whole generation of analytic philosophers, including such figures as John McDowell, Christopher Peacocke, and Crispin Wright, Dummett’s work was not easy reading. His stature amongst colleagues was immense, but inevitable difficulties in communicating his theories concisely prevented him from achieving the wider attention he deserved. When asked by his publisher to supply a new introduction to a work on Frege, for example, Dummett supplied 500 pages of material.

But his commitment to truth had very practical applications, and ones which he pursued with vigour and personal courage. In particular, throughout his career he maintained a deep interest in the ethical and political issues concerning refugees and immigration, informed by what he described as “an especial loathing of racial prejudice and its social manifestations”.

In the post-war period, Dummett and his wife Ann were among the earliest and most dogged campaigners on race relations. In 1958 they co-founded the Institute of Race Relations think tank and in the 1960s, as the trickle of immigration became a flood, they drove a battered van to Heathrow Airport day after day to take up the cases of Asian and West Indian immigrants threatened with deportation. On one occasion they were arrested and prosecuted after staging a protest against a market stallholder who refused to serve black customers. Police dropped charges and the then Home Secretary, Roy Jenkins, apologised.

Dummett saw the root of the problem as lying in the political system. In his book On Immigration and Refugees (2001), he argued that lurking behind the egalitarian veneer of democracy is the more manipulative principle of playing on people’s prejudices to gain votes. This, when applied to issues of immigration, has invariably led to a jingoistic policy – a policy founded, essentially, on racism. In Britain, according to Dummett, much of the blame rested with the Home Office, a department which he accused of “decades of hopeless indoctrination in hostility”, first against Commonwealth immigrants, and later against asylum seekers and refugees. “For the Home Office,” he once wrote, “the adjective 'bogus’ goes as automatically with 'asylum seeker’ as 'green’ does with 'grass’.”

Dummett’s political concerns made him increasingly convinced that political parties were essentially undemocratic institutions which, through a distorted voting system and the use of whipping procedures in Parliament, had become little more than “devices for frustrating the will of the majority”. In Voting Procedures (1984) and Principles of Electoral Reform (1997) he proposed a proportional representation system known as the Quota Borda or Quota Preference Score system, a highly complex arrangement designed to encourage consensus by giving candidates the incentive to appeal to as wide as possible a cross-section of voters.

But Dummett was perfectly capable of turning his mind to lighter matters. He was an avid reader of science fiction and an enthusiastic player and historian of card games – the Journal of the Playing Card Society was one of many to which he contributed articles. In The Game of Tarot: From Ferrara to Salt Lake City (1980) one of several publications in this field, he argued that in the Middle Ages the Tarot was used as a set of playing cards and that it only acquired its association with the occult in the 18th century.

Michael Anthony Eardley Dummett was born on June 27 1925. He attended Winchester College, where he was a Scholar, and served in the Armed Forces from 1943 to 1947, first in the Royal Artillery, and then in the Intelligence Corps in India and Malaya. After his military service, he went on a scholarship to Christ Church College, Oxford, graduating with First Class Honours in PPE in 1950, whereupon he was immediately given a fellowship at All Souls.

He remained based in Oxford all his life and in 1979 was appointed Wykeham Professor of Logic, a chair which he held until his retirement in 1992. Concurrently with these appointments, however, he frequently lectured abroad, particularly in America, where he was variously a visiting professor at Stanford, Minnesota and Princeton. In 1976 he was William James Lecturer in Philosophy at Harvard.

Although Dummett was brought up an Anglican, by the age of 13 he regarded himself as an atheist. In 1944, however, he converted to Roman Catholicism. In the early part of his career he regarded himself as a “Wittgensteinian” but he did not accept the view, expressed by some admirers of Wittgenstein, that philosophy has no practical relevance to people’s lives or that metaphysics is an ultimately futile pursuit. Further, Dummett never saw faith and logic as in any way mutually exclusive.

Dummett’s first philosophical article was a book review, published in Mind in 1953. He went on to publish many more, his articles later being compiled into three volumes. His first book, Frege: Philosophy of Language (1973), was a long time in coming partly because he had put his academic career on hold to campaign against racism. A second, enlarged, edition of the book was published in 1981, the same year that saw the publication of The Interpretation of Frege’s Philosophy.

In the 1970s Dummett also published Elements of Intuitionism (1977) and his first collection of papers, Truth and Other Enigmas (1978). Later works included Frege and Other Philosophers (1991) and The Seas of Language (1993). Also in 1993 he published Grammar and Style, a book prompted by his infuriation with declining standards of literacy. Last year he summed up the intellectual pursuit to which he had dedicated his life in The Nature and Future of Philosophy.

Dummett was a Fellow of the British Academy and was knighted in 1999 for “services to philosophy and to racial justice”. He celebrated the award with a demand that the Home Office’s entire immigration staff be replaced.

Michael Dummett married, in 1951, Ann Chesney. She survives him with three sons and two daughters; a son and a daughter predeceased him.

Professor Sir Michael Dummett, born June 27 1925, died December 27 2011