I think it is safe to say that for most people, in late 20th century, the most famous indeterminate piece would be John Cage’s 4’33”. It is, however; difficult to say how indeterminate that piece really is, the sounds that occur during the musician(s) stillness changes from performance to performance, but the action (or non-action) of the musicians(s) remains consistent regardless of who is “playing” the piece. It lasts for a set amount of time and I think that modern audiences are inclined to honor the concept of “silence” although I don’t believe that absolute silence was ever Cage’s goal.
I mentioned in the previous discussion that I feel that new notation styles cannot really (in my mind) be talked about separately from indeterminacy. It seems to me that the scores of the American composers were far more concerned with the esthetic beauty of what was on the page rather than the sound produced. The best example of this is Earle Brown’s piece December 1952 which looks very much like a modernist picture that might hang in a museum. Morgan notes that the sound/music produced by musicians interpreting this score is really just guided by whatever they feel the page is telling them to do, but it is mostly a “free improvisation.” When this kind of what might be called “ultra-indeterminate” writing was done by the European composer Stockhausen, instead of graphic representations he used verbal. The score for Intensity consists of directions for improvisation that take the form of a poem.
These two pieces might give some insight into the differences in thinking regarding indeterminacy, the American visual versus the European poetic, but this is very difficult when citing individual works by individual composers. Morgan mentions that Cage’s manuscripts had been put on display as visual works of art, and it doesn’t appear that this is true of any of the European composers. On the other hand, if we examine the score for the String Quartet by Lutoslawski, what we see are numerous text comments on how to interpret and perform the manuscript, so it appears that while the pitches and rhythms are displayed in the notation, the true direction comes from the words written by the composer. There are, of course, many pieces that have a profound visual aesthetic with regards to score which were innovations of European composers, the best among these appear on page 377 and is Bussotti’s Siciliano. Morgan notes that there are no directions for interpreting the score but that the use of numbered parts might give some indication. Pieces like this seem as though the composer was setting forth a musical puzzle and the solving of that puzzle is related to the aesthetic power of its performance, as if to say that in figuring out how to play the piece the game is won on the part of the performer.
I would like to make mention of an area with which I have a fair amount of experience, that being Hindustani music. In realizing a Raga, there are essentially musical notes that are available for improvisation (especially in the beginning of the piece) usually there is an indication of which patterns will sound the most pleasing and therefore should be repeated a number of times. There are also two “most important” notes in the Rag which the melodies should gravitate towards. The middle section of a composition tends to be more structured but there is always room for interpretation. The idea is to make a piece individual to each performer as opposed to western conceptions of the traditional score. To me, this is a prime example of indeterminacy going back a thousand or so years. We see similar notions in the music of the Arab people (although I am not very well versed on that system of music). Morgan mentions that virtually all of the Minimalist composers studied Indian music of some kind, but it is interesting that in this aspect of performance of pieces that there was not as much interest on the part of the indeterminists.