The use of chance in music written during the last ten years has been much discussed. Expressions like ‘indeterminate music’, ‘aleatoric processes’ are thrown about with little attempt at definition. The situation badly needs clarifying: at least two distinct ideas which involve chance have been used.
Firstly, chance operations have been used to compose—e.g. in John Cage’s ‘Music of Changes’ for piano. Secondly, after a piece has been written down, some aspects of performance are left unspecified—e.g. Boulez’ 3rd piano sonata; Stockhausen’s Piano piece XI. (Thirdly, in some of Cage’s music, both these things happen.)
To understand why Cage uses chance operations to compose, one needs to know what he believes about things in general. His book Silence, a collection of lectures and essays, includes a number of observations about sound, music and the world, Zen philosophy and stories, and personal anecdotes told in a style which recalls Gertrude Stein. From all this emerges a picture of a philosophy of non-involvement which is at least consistent in a bizarre way.
He is fond of the son of mental juggling with paradox which can be extracted from discussion of chance, accident and their role in the world: phrases which have the superficial appearance of being significant and thought-provoking, such as ‘Chance is a leap out of one’s own reach’, occur often. He seems to accept things as they are. He looks with a sort of wonder on things just because they exist or happen; his attitude to the world is one of perpetual, child-like amazement; he seems content to observe things, without any desire to change or influence them. Here is one of his anecdotes. He tells how, after a concert, he said to a composer whose piece he had heard:
‘“Well, I enjoyed the music, but I didn’t agree with that programme note about there being too much pain in the world.” He said “What, don’t you think there’s enough?” I said “I think there’s just the right amount.”’