Cardew was born in Winchcombe, Gloucestershire. He was the second of three sons whose parents were both artists—his father was the potter Michael Cardew. The family moved to Wenford Bridge Pottery Cornwall a few years after his birth where he was later accepted as a pupil by the Canterbury Cathedral School which had evacuated to the area during the war due to bombing. His musical career thus began as a chorister. From 1953 to 1957, Cardew studied piano, cello, and composition at the Royal Academy of Music in London.
In 1957, Cardew performed in the British premiere of Pierre Boulez's Le marteau sans maître (having learnt to play the guitar for the occasion as no professional guitar player was available). Having won a scholarship to study at the recently established Studio for Electronic Music in Cologne, Cardew served as an assistant to Karlheinz Stockhausen from 1958 to 1960. He was given the task of independently working out the composition plans for the German composer's score Carré, and Stockhausen noted:
As a musician he was outstanding because he was not only a good pianist but also a good improviser and I hired him to become my assistant in the late 50s and he worked with me for over three years. I gave him work to do which I have never given to any other musician, which means to work with me on the score I was composing. He was one of the best examples that you can find among musicians because he was well informed about the latest theories of composition as well as being a performer.
Most of Cardew's compositions from this period make use of the integral and total serialist languages pioneered by Boulez and Stockhausen.
In 1958, Cardew witnessed a series of concerts in Cologne by John Cage and David Tudor which had a considerable influence on him, leading him to abandon post-Schönbergian serial composition and develop the indeterminate and experimental scores for which he is best known. He was particularly prominent in introducing the works of American experimental composers such as Morton Feldman, La Monte Young, Earle Brown, Christian Wolff, and Cage to an English audience during the early to mid sixties and came to have a considerable impact on the development of English music from the late sixties onwards.
Cardew's most important scores from his experimental period are Treatise (1963–67), a 193-page graphic score which allows for considerable freedom of interpretation, and The Great Learning, a work in seven parts or "Paragraphs," based on translations of Confucius by Ezra Pound. The Great Learning instigated the formation of the Scratch Orchestra. During those years, he took a course in graphic design and he made his living as a graphic designer at Aldus Books in London.
In 1966, Cardew joined the free improvisation group AMM as cellist and pianist. AMM had formed the previous year and included English jazz musicians Lou Gare, Eddie Prévost, Keith Rowe, and one of his first students at the Royal Academy Christopher Hobbs. Performing with the group allowed Cardew to explore music in a completely democratic environment, freely improvising without recourse to scores.
While teaching an experimental music class at London's Morley College in 1968, Cardew, along with Howard Skempton and Michael Parsons formed the Scratch Orchestra, a large experimental ensemble, initially for the purposes of interpreting Cardew's The Great Learning. The Scratch Orchestra gave performances throughout Britain and elsewhere until its demise in 1972. It was during this period that the question of art for whom was hotly debated within the context of the Orchestra, which Cardew came to see as elitist despite its numerous attempts to make socially accessible music.
After the demise of the Orchestra, Cardew became more directly involved in left-wing politics and abandoned avant-garde music altogether, adopting a populist though post-romantic tonal style. He spent 1973 in West Berlin on an artist's grant from the City, where he was active in a campaign for a children's clinic. During the 1970s, he produced many songs, often drawing from traditional English folk music put at the service of lengthy Marxist-Maoist exhortations; representative examples are Smash the Social Contract and There Is Only One Lie, There Is Only One Truth. In 1974, he published a book entitled Stockhausen Serves Imperialism, which denounced, in Maoist self-critical style, his own involvement with Stockhausen and the Western avant-garde tradition.
Cardew was active in various causes in British politics, such as the struggle against the revival of neo-Nazi groups in Britain, and subsequently was involved in the People's Liberation Music group with Laurie Scott Baker, John Marcangelo, Vicky Silva, Hugh Shrapnel, Keith Rowe and others. The group developed and performed music in support of various popular causes including benefits for striking miners and Northern Ireland.
Cardew became a member of the Communist Party of England (Marxist-Leninist) in the 1970s, and in 1979 was a co-founder and member of the Central Committee of the Revolutionary Communist Party of Britain (Marxist-Leninist). His creative output from the demise of the Scratch Orchestra until his death reflected his political commitment. Cardew stated his attitude towards the avant-garde in Stockhausen Serves Imperialism:
Cardew's efforts to politicise culture in Britain were influenced by his relationship with Hardial Bains, the Canadian communist leader and a leading anti-revisionist politician. Bains contributed the lyrics to Cardew's signature song from his later period, We Sing for the Future.
Cardew died on 13 December 1981, the victim of a hit-and-run car accident near his London home in Leyton. The driver was never found.
Musician John Tilbury, in his book Cornelius Cardew—A Life Unfinished suggests that the possibility that Cardew was killed because of his prominent Marxist-Leninist involvement "cannot be ruled out". Tilbury quotes a friend of Cardew's, John Maharg; "MI5 are quite ruthless; people don't realise it. And they kill pre-emptively".
A 70th Birthday Anniversary Festival, including live music from all phases of Cardew's career and a symposium on his music, took place on 7 May 2006 at the Cecil Sharpe House in London.In 1999 Page 183 of Cardew's Treatise was performed by the experimental rock group Sonic Youth on their album SYR4: Goodbye 20th Century.
"Cornelius Cardew" is the name of the unemployed pipe-fitter in Alan Moore's Skizz.
A character called "Cornelius Cardew" appears (as a caricature of a political radical) in the 1985 film The Shooting Party.
The German musician and composer Ekkehard Ehlers published a Cardew-inspired work in 2001, titled Ekkehard Ehlers plays Cornelius Cardew, which was released on Staubgold Records.
The US band The Music Lovers name-checked Cardew in the song, "Thank You, Cornelius Cardew". It appears on their 2006 album, The Music Lovers' Guide for Young People.
Controversial Danish/Faroese musician Goodiepal used Treatise to debate abstract notation in his Radical Computer Music lectures.
The band The Caribbean have written a song entitled "Stockhausen Serves Imperialism".
The Great Learning Paragraphs 2 and 7 (1971; re-released 2002) (Deutsche Grammophon/Universal Classics 471 572).
The Great Learning All paragraphs, four CD (Poland 2010) (Bolt Records 1008).
Thälmann Variations (solo piano, rec. 1975 in New York, publ. posthumously, 1986)
Cornelius Cardew Piano Music musicnow 1991 (the composer; Andrew Ball and John Tilbury, Andrew Bottrill, 79.00)
We Sing for the Future! Interpretations of two compositions for solo piano (We Sing for the Future!, Thälmann Variations) by Frederic Rzewski (2002) (New Albion)
Four Principles On Ireland And Other Pieces (Ampersand)
Chamber Music 1955–1964 Apartment House (2001) (Matchless Recordings mrcd45)
Cornelius Cardew — piano music 1959–70 (1996) John Tilbury (Matchless Recordings mrcd29)
AMMMUSIC — Cardew as an improviser. With Lou Gare, Eddie Prévost, Lawrence Sheaff and Keith Rowe, London 1966. CD release (ReR Megacorp.)
AMM The Crypt – 12 June 1968 Cardew as an improviser. With Lou Gare. Christopher Hobbs, Eddie Prévost and Keith Rowe. Double CD. (Matchless Recordings MRCD05)
AMM LAMINAL Cardew as an improviser. Three CD retrospective AMM box set published in 1996. Cardew performs on one CD, titled The Aarhus Sequences (1969). (Matchless Recordings MRCD31)
"Cornelius Cardew: Works 1960–70" (2010) with John Tilbury, Michael Francis Duch and Rhodri Davies