Indeterminacy in music, which began early in the twentieth century in the music of Charles Ives, and was continued in the 1930s by Henry Cowell and carried on by his student, the experimental music composer John Cage beginning in 1951 (Griffiths 2001), came to refer to the (mostly American) movement which grew up around Cage. This group included the other members of the so-called New York School: Earle Brown, Morton Feldman and Christian Wolff. Others working in this way included the Scratch Orchestra in the United Kingdom (1968 until the early 1970s) and the Japanese composer Toshi Ichiyanagi (born 1933).

In 1958 Cage gave a lecture in Brussels called "Indeterminacy: New Aspect of Form in Instrumental and Electronic Music" (given again in 1959 at Teacher's College, Columbia). The lecture consisted of a number of short stories read by Cage in exactly one minute; because of this time limit the speed of Cage's delivery varied enormously. The second performance and a subsequent recording (Cage 1959) contained music, also by Cage, played by David Tudor at the same time.

One strand of indeterminacy in music sees it as an aesthetic endeavour that strives to dissolve any fixed properties of music sound into a fluid process and do away with the traditional control of the composer over the material. In its most radical form, all sounds have equal value: sounds chosen by the composer, by the performer, and all the unforeseen and unpredictable sounds that surround us every day. Indeterminacy in this view is philosophically opposed to aleatoric music: there the indeterminate element was kept under careful control by the composer, usually by offering the performers a limited number of possibilities to choose from.

References

• Cage, John. 1961. "Indeterminacy", in his Silence: Lectures and Writings, 35–40. Middletown, Conn.: Wesleyan University Press.
• Childs, Barney. 1974. "Indeterminacy", in Dictionary of Twentieth-Century Music, edited by John Vinton, [pages ?]. London: Thames and Hudson. ISBN 0500011001 American edition published under title Dictionary of Contemporary Music (New York: E. P. Dutton, 1974) ISBN 0525091254
• Griffiths, Paul. 2001. "Aleatory". The New Grove Dictionary of Music and Musicians, ed. S. Sadie and J. Tyrrell. London: Macmillan.
• Nyman, Michael. 1974. Experimental Music: Cage and Beyond. London: [publisher]; New York: Schirmer Books. ISBN 0028712005 Second edition 1999, Cambridge and New York: Cambridge University Press. ISBN 0521652979 (cloth) ISBN 0521653835 (pbk)
• Sutherland, Roger. 1994. New Perspectives in Music. London: Sun Tavern Fields. ISBN 0951701266

Discography

• Cage, John. 1959. Indeterminacy: New Aspects of Form in Instrumental and Electronic Music. Ninety Stories by John Cage, with Music. John Cage, reading; David Tudor, music (Cage, Solo for Piano from Concert for Piano and Orchestra, with Fontana Mix). Folkways FT 3704 (2 LPs). Reissued 1992 on Smithsonian/Folkways CD DF 40804/5 (2 CDs).