This pattern, of giving equal billing to what each style is not, in comparison with its predecessor, as what it is, has always vaguely bugged me, even as I deployed it myself. Being simply a negation of previous practice, it seems to me, wouldn't inspire the profound and often joyous creativity that accompanied most of these movements. (As a benchmark, compare with political thought: did anti-Communism ever strike you as a particularly rich intellectual playground? Anti-Zionism? Making fun of the French? Well, maybe that last one.) And yet, all those turnovers of the musical odometer were contrasts, breaking with the previous generation in crucial ways.
I think there's a more interesting way to think about this, related to a pattern found perhaps most notably in 19th-century history. One of the main undercurrents of Victorian thought in England, for example, was the steady erosion of religious dogma by rational science. It's around the 1850s and 60s that this particular wave crests, and writers and thinkers begin to seriously propose atheism, as profound a negation as you could come up with at that time. Needless to say, mainstream Victorians were horrified by the atheists in their midst, but what really puzzled them was that the heathens were so happy, even giddy, about the prospect of a godless universe; as Charlotte Brontë remarked, "The strangest thing is, that we are called on to rejoice over this hopeless blank." Or as the theistic Thomas Carlyle wrote in his journal, "An immense development of Atheism is dearly proceeding, and at a rapid rate, and in joyful exultant humour."
But what brought the atheists such joy was not the absence of a benevolent deity, but the way denying His existence cleared away an entire philosophical bramble-patch in one stroke. In his vital study The Victorian Frame of Mind, 1830-1870, the late Wellesley professor Walter E. Houghton put it this way, commenting on the above Carlyle quote:
In [Carlyle's] fear of materialism he forgot the release it could bring from the weary and frustrating effort to reconcile religion and science.... Accept it, wrote John Morley, with his own experience in mind (the trying struggle to maintain his Christianity, followed by the happy conversion to agnosticism), and "the active energies are not [any longer] paralysed by the possibilities of enfeebling doubt, nor the reason drawn down and stultified by apprehension lest its methods should discredit a document, or its inferences clash with a dogma, or its light flash unseasonably on a mystery." The mind is freed from the whole pressure, social and personal, to think within a traditional context which has become incredible.In other words, the need to work around the question disappears, because the question itself becomes meaningless. The radical Victorians squeezed the elephant in the room out the door, and were thrilled to discover how much space it freed up for new furniture.
If we look at epochs in the history of classical music in this light, not what each movement cast aside from the previous one, but what seemingly intractable aesthetic argument it rendered moot, you can start to understand the infusion of energy with each turn of the wheel. Atonality isn't a casting aside of tonality, but a slice through the Gordian knot of trying to reconcile an increasingly dissonant vocabulary with formal structures built around consonance. Minimalism isn't a throwback reaction to serialist dogma, but but a way to cast aside the seeming incompatibility of the intuitive rhetoric of triadic tonality with the deteministic processes of the 12-tone method. Because of the nature of music, this sort of thinking doesn't necessarily imply any progressive timeline, either: there are still composers who find that the inherent conflicts in Romanticism, or serialism, or what have you, provide the appropriate drama for their expressive goals. But for other composers, such questions only crowd the table, and need to be swept aside.
This way of thinking can help explain supposed musical revolutions that don't, in retrospect, seem all that revolutionary. Neoclassicism, for example, at the remove of the better part of a century, often sounds tame and hermetic compared with other musical currents between the wars. But as an effort to work through classical music's perennial wrestling between the push for innovation and the veneration of the past, it fits the pattern nicely. The idea also reveals distant mirrors: both the 14th-century ars nova and current post-minimalism can in part be seen as a dissolution of the supposed boundary between art and vernacular musics.
Historical upheaval fans will no doubt by now be thinking that I'm promulgating a view of music history as a series of quasi-Hegelian dialectics. They're right, to a point. But it's a good way to get a sense of what Hegel and those who appropriated Hegel's ideas were really after. The caricature of the dialectic is a boiling-down of every historical or philosophical pattern to two concepts in conflict with each other—depending on the caricature, either one concept inevitably prevails, or the two are mashed up into a crude "synthesis." But the real Hegelian process is finding what the fundamental, intractable, unresolvable problems of a situation are, and then figuring how to change the situation so such problems cease to be an issue. That's what Marx—the most famous, and infamous, disciple of the dialectic—tried to do. It's what the Victorian atheists tried to do. It's what composers have periodically tried to do throughout history.
And it's why all those 19th-century revolutionaries had such consistent and, for the most part, unwarranted optimism, the old conflicts melting away to nothing, a clear, wide path seemingly open in front of them. The socialists saw their revolution founder on the shoals of human nature, but music, happily, lives in a parallel universe of unlimited, unhindered possibility. The Romantics, the futurists, the minimalists, they all felt revolutionary euphoria, for the same reason that revolutionaries do—but composers push to new dialectic syntheses in a forum far more amenable to them than the world of politics and money. Utopias can't survive in everyday life, but in art, they continually sprout anew, a lush, perennial garden.
I had this thing drafted out before I saw Phil's "Dial M" post on, among other things, utopian visions in popular music. You know what they say: one of us, it's a crackpot theory—two of us, it's a movement!