Gellner was born in Paris to Anna, née Fantl, and Rudolf, a lawyer, an urban intellectual German-speaking Jewish couple from Bohemia (which since 1918 was part of the newly established Czechoslovakia). Julius Gellner was his uncle. He was brought up in Prague, attending a Czech primary school before entering the English-language grammar school. This was Kafka's tricultural Prague, he told John Davis of Oxford University: anti-Semitic but stunningly beautiful, a city he later spent years longing for.

In 1939, when Gellner was 13 years old, the rise of Adolf Hitler in Germany persuaded his family to leave Czechoslovakia and move to St Albans, just north of London, where Gellner attended St Albans Grammar School. At the age of 17, he won a scholarship to Balliol College, Oxford as a result of what he called "Portuguese colonial policy," which involved "[keeping] the natives peaceful by getting able ones from below into Balliol."

At Balliol, he studied Philosophy, Politics and Economics (PPE), specializing in philosophy. He interrupted his studies after one year to serve with the 1st Czechoslovak Armoured Brigade, which took part in the siege of Dunkirk, then returned to Prague to attend university there for half a term.

During this period, Prague lost its strong hold over him: foreseeing the communist takeover, he decided to return to England. One of his recollections of the city in 1945 was a communist poster saying: "Everyone with a clean shield into the Party," ostensibly meaning that those whose records were good during the occupation were welcome. In reality, Gellner said, it meant exactly the opposite:

'If your shield is absolutely filthy we'll scrub it for you; you are safe with us; we like you the better because the filthier your record the more we have a hold on you." So all the bastards, all the distinctive authoritarian personalities, rapidly went into the Party, and it rapidly acquired this kind of character. So what was coming was totally clear to me, and it cured me of the emotional hold which Prague had previously had over me. I could foresee that a Stalinoid dictatorship was due: it came in '48. The precise date I couldn't foresee, but that it was due to come was absolutely obvious for various reasons ... I wanted no part of it and got out as quickly as I could and forgot about it.'

He returned to Balliol College in 1945 to finish his degree, winning the John Locke prize and taking first class honours in 1947. That same year, he began his academic career at the University of Edinburgh as an assistant to Professor John Macmurray in the Department of Moral Philosophy. He moved to the London School of Economics in 1949, joining the sociology department under Morris Ginsberg. Ginsberg admired philosophy, and believed that philosophy and sociology were very close to each other.

He employed me because I was a philosopher. Even though he was technically a professor of sociology, he wouldn't employ his own students, so I benefited from this, and he assumed that anybody in philosophy would be an evolutionary Hobhousean like himself. It took him some time to discover that I wasn't.

Leonard T. Hobhouse had preceded Ginsberg as Martin White Professor of Sociology at the LSE. Hobhouse's Mind in Evolution (1901) had proposed that society should be regarded as an organism, a product of evolution, with the individual as its basic unit, the subtext being that society would improve over time as it evolved, a teleological view Gellner firmly opposed.

Ginsberg ... was totally unoriginal and lacked any sharpness. He simply reproduced the kind of evolutionary rationalistic vision which had already been formulated by Hobhouse and which incidentally was a kind of extrapolation of his own personal life: starting in Poland and ending up as a fairly influential professor at LSE. He evolved, he had an idea of a great chain of being where the lowest form of life was the drunk, Polish, anti-Semitic peasant and the next stage was the Polish gentry, a bit better, or the Staedtl, better still. And then he came to England, first to University College under Dawes Hicks, who was quite rational (not all that rational—he still had some anti-Semitic prejudices, it seems) and finally ended up at LSE with Hobhouse, who was so rational that rationality came out of his ears. And so Ginsberg extrapolated this, and on his view the whole of humanity moved to ever greater rationality, from drunk Polish peasant to T.L. Hobhouse and a Hampstead garden.

Gellner's critique of linguistic philosophy in Words and Things (1959) focused on J.L. Austin and the later work of Ludwig Wittgenstein, criticizing them for failing to question their own methods. The book brought Gellner critical acclaim. He obtained his Ph. D. in 1961 with a thesis on "Organization and the Role of a Berber Zawiya," and became Professor of Philosophy, Logic and Scientific Method just one year later. Thought and Change was published in 1965, and in State and Society in Soviet Thought (1988), he examined whether Marxist regimes could be liberalized.

He was elected to the British Academy in 1974. He moved to Cambridge in 1984 to head the Department of Anthropology, holding the William Wyse chair and becoming a fellow of King's College, which provided him with a relaxed atmosphere where he enjoyed drinking beer and playing chess with the students. Described by the Oxford Dictionary of National Biography as "brilliant, forceful, irreverent, mischievous, sometimes perverse, with a biting wit and love of irony," he was famously popular with his students, willing to spend many extra hours a day tutoring them, and was regarded as a superb public speaker and gifted teacher.

His Plough, Sword and Book (1988) investigated the philosophy of history, and Conditions of Liberty (1994) sought to explain the collapse of socialism. In 1993, he returned to Prague, now free of communism, and to the new Central European University, where he became head of the Center for the Study of Nationalism, a program funded by George Soros, the American billionaire philanthropist, to study the rise of nationalism in the post-communist countries of eastern and central Europe. On November 5, 1995, after returning from a conference in Budapest, he suffered a heart attack and died at his flat in Prague, one month short of his 70th birthday.

With the publication in 1959 of Words and Things, his first book, Gellner achieved fame and even notoriety among his fellow philosophers, as well as outside the discipline, for his fierce attack on ordinary language philosophy (or "linguistic philosophy", Gellner's preferred phrase). Ordinary language philosophy, in one form or another, was the dominant approach at Oxbridge at the time (although the philosophers themselves denied they were part of any unified school). He first encountered the strong ideological hold of linguistic philosophy while at Balliol:

Words and Things is fiercely critical of the work of Ludwig Wittgenstein, J. L. Austin, Gilbert Ryle, Antony Flew, Peter Strawson and many others. Ryle refused to have the book reviewed in the philosophical journal Mind (which he edited), and Bertrand Russell (who had written an approving foreword) protested in a letter to The Times. A response from Ryle and a lengthy correspondence ensued.

It was in the 60s that Gellner discovered his great love of social anthropology. Chris Hann, Professor of Anthropology and Dean of Social Sciences at the University of Kent, writes that, following the hard-nosed empiricism of Bronis?aw Malinowski, Gellner made major contributions to the subject over the next 40 years, ranging from "conceptual critiques in the analysis of kinship to frameworks for understanding political order outside the state in tribal Morocco (Saints of the Atlas, 1969); from sympathetic exposition of the works of Soviet Marxist anthropologists to elegant syntheses of the Durkheimian and Weberian traditions in western social theory; and from grand elaboration of 'the structure of human history' to path-breaking analyses of ethnicity and nationalism (Thought and Change, 1964; Nations and Nationalism, 1983)".

In 1983, Gellner published Nations and Nationalism. For Gellner, "nationalism is primarily a political principle that holds that the political and the national unit should be congruent". Nationalism only appeared and, Gellner argues, became a sociological necessity in the modern world. In previous times ("the agro-literate" stage of history) rulers had little incentive to impose cultural homogeneity on the ruled. But in modern society, work becomes technical. One must operate a machine, and as such one must learn. There is a need for impersonal, context-free communication and a high degree of cultural standardisation.

Furthermore, industrial society is underlined by the fact that there is perpetual growth - employment types vary and new skills must be learned. Thus, generic employment training precedes specialised job training. On a territorial level, there is competition for the overlapping catchment areas (e.g. Alsace-Lorraine). To maintain its grip on resources, and its survival and progress, the state and culture must for these reasons be congruent. Nationalism therefore is a necessity.

Criticisms of Gellner's theory:

• It is too functionalist. Critics charge that Gellner explains the phenomenon with reference to the eventual historical outcome - industrial society could not 'function' without nationalism (Tambini 1996) .
• It misreads the relationship between nationalism and industrialization (Smith 1998).
• It poorly accounts for national movements of ancient Rome, Greece, etc. claiming An alum type argument; insisting that nationalisms is tied in 'modernity', and can not exist without a clearly defined modern industrialization. (Smith 1995)
• It fails to account for nationalism in non-industrial society and resurgences of nationalism in post-industrial societies (Smith 1998).
• It cannot explain the passions generated by nationalism. Why should anyone fight and die for his country? (Connor 1993)
• It fails to take into account the role of war and the military in fostering both cultural homogenization and nationalism, ignoring in particular the relationship between militarism and compulsory education (Conversi 2007).

Books

• Words and Things, A Critical Account of Linguistic Philosophy and a Study in Ideology, London: Gollancz; Boston: Beacon (1959). Also see correspondence in The Times, 10 November to 23 November 1959.
• Thought and Change (1964)
• Saints of the Atlas (1969)
• Contemporary Thought and Politics (1974)
• The Devil in Modern Philosophy (1974)
• Legitimation of Belief (1974)
• Spectacles and Predicaments (1979)
• Soviet and Western Anthropology (1980) (editor)
• Muslim Society (1981)
• Nations and Nationalism (1983)
• Relativism and the Social Sciences (1985)
• The Psychoanalytic Movement (1985)
• The Concept of Kinship and Other Essays (1986)
• Culture, Identity and Politics (1987)
• State and Society in Soviet Thought (1988)
• Plough, Sword and Book (1988)
• Postmodernism, Reason and Religion (1992)
• Conditions of Liberty (1994)
• Anthropology and Politics: Revolutions in the Sacred Grove (1995)
• Nationalism (1997)
• Language and Solitude: Wittgenstein, Malinowski and the Habsburg Dilemma (1998)