Classical composers do not make music – they write scores which specify the scenarios followed by performing artists who create actual sonic structures. Composers could thus choose an extremely modest interpretation of their role. Since they trust the creativity of their performers, they could be content to view themselves as mere providers of material, without necessarily anticipating how the performer would use it, or entertaining expectations about the eventually resulting sounds. Since the early 1960's, this manner of composing has been been practiced in several different ways. Examples are:

•  Graphic scores whose interpretation is partially or completely unspecified. The most radical proponent of this genre is Anastesis Logothetis. The anthology Notations, edited by John Cage, provides examples from many composers.

•    "Meta-scores" with an infinite variety of structurally different realisations, from which the performer may choose at his own discretion. A very complex example is Plus-Minus by Karlheinz Stockhausen.

•    "Word pieces": generic verbal descriptions of musical events. This genre was practiced by George Brecht, La Monte Young, Henry Flynt, Dick Higgins, George Maciunas, and other composers associated with the International Fluxus Movement.
  Some of these pieces do not specify any constraints. And some are impossible to perform; that is when music becomes concept art.

Sometimes, the transfer of the composer's authority to the performer's autonomy symbolizes a political stance. John Cage, one of the most enthusiastic advocates of indeterminacy, was a card-carrying anarchist.

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Discuss also:

Umberto Eco: "The Poetics of the Open Work."

Konrad Boehmer re John Cage.

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Essay topic

Investigate the technique and meaning of indeterminacy in Karlheinz Stockhausen's work. Discuss Plus-Minus, the "concept-pieces", his belief in magic, his reaction to the destruction of the World Trade Center. Note that in some of his early serial works, indeterminacy was a parameter.

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It is obvious that to appreciate the many facets of open forms is beyond the means of any ordinary listener and possibly only of real significance to the composer himself.

R. Smith Brindle: The New Music, p. 72.

    

Interactivity

One may also organize a musical performance so as to allow the public to exercise a decisive influence on its course. The first such "interactive" pieces were developed in the context of post-serial non-deterministic music. (Henri Pousseur's "Votre Faust" involves a "voting machine").

In a much less formal way, the "happenings" by Allan Kaprow and others also allow more audience interaction than traditional music or theatre. In some concerts by The New Electric Chamber Music Ensemble (1966), members of the audience completely took over the stage in the course of the evening.