Kyle Gann writes, in a long disquisition on Schoenberg and twelve-tone music: "I think what we need to do is quit teaching 20th-century history with a dishonest thumb on the scale in Schoenberg’s favor. For decades, academic historians have presented the Second Vienna School as central to a European modernist canon, at the expense of dozens of other composers more popular, outside academia, than Schoenberg: Copland, Milhaud, Cowell, Hindemith, Shostakovich, Gershwin, Messiaen, Britten, Weill, Cage, Partch. It’s time to restore these composers to the center of 20th-century music, and redraw 12-tone music as the interesting but infertile cul-de-sac that it was." This is more or less what I am trying to do in my book, though I wouldn't go so far as to say that Schoenberg is less significant than Milhaud, or, for that matter, less popular than Partch. The big story in 20th-century music is, in my view, not the "death of tonality," which in fact never happened, but the rejuvenation of tonality, which began with Debussy and Satie. Schoenberg's positive achievement was to add new harmonies to the field. He didn't see it that way, of course; he wanted the new chords to replace the old. Even he, at the end of his life, realized that his earlier edicts had been too severe, as his correspondence with the hyper-dogmatic René Leibowitz shows.
I'm not sure about Kyle's choice of the word "infertile," though. Sometimes fertility works in mysterious ways. What's always worth mentioning about twelve-tone music is that it's not the same thing as "atonality," which is a fuzzy concept in itself. It does not dictate the content of a piece. It does not forbid the use of tonal elements, such as major or minor triads; indeed, unless precautions are taken in the construction of the row, it often generates them "by accident," as happens, rather mischievously, in much of Milton Babbitt's music both early and late. If you arrange your rows to encourage triads, say by choosing C E G D F A F# A# C# G# B D#, you will end up with a Richard Strauss-style barrage of chords: C major! D minor! No, wait! F# major! G# minor! Crazy! Whee! Alban Berg discovered this loophole right away, and rejoiced in it; he was able to resume writing grand late-Romantic music, which he had never really given up, while ostensibly following his Master's rules. He was like those prep-school kids who interpret "coat and tie" to mean sweatpants and T-shirts with tie and coat on top. It was Sibelius who said that Berg was Schoenberg's greatest work.
Paradox: By arguing with Schoenberg, we are reaffirming his importance. — Brendan McNamara has more.