The 20th century shattered Western music into fragments. Schoenberg abandoned tonality. Stravinsky shocked Paris with primitivism. Meanwhile, jazz was being born in New Orleans - and popular music would never be the same.
The twentieth century brought the most radical transformation in Western music since the invention of tonality itself, producing a fragmentation of musical language so thoroughgoing that by mid-century no single style, tradition, or set of aesthetic values could claim the kind of broad cultural authority that tonality had previously provided. The causes of this fragmentation were multiple and converging: the philosophical impact of Darwin, Freud, and Nietzsche on assumptions about human nature and social progress; the traumatic experience of the First World War and its demolition of European confidence in rationality and civilization; the influence of non-Western musical traditions — African drumming, Indonesian gamelan, Japanese court music — increasingly available to European composers through ethnographic recordings and international exhibitions; and the internal logic of the tonal tradition itself, which Wagner and his successors had pushed to a point where further expansion seemed to require either resolution or rupture.
Arnold Schoenberg (1874-1951) chose rupture. His Three Piano Pieces Op. 11, composed in 1909, abandoned tonal centers entirely, organizing musical material without reference to key or the hierarchical chord relationships of the tonal system. This free atonality was followed, after years of compositional silence during which Schoenberg searched for a new organizing principle, by the development of the twelve-tone technique: a compositional method in which all twelve chromatic pitches were arranged into a predetermined series or row, and the composition was generated entirely from transformations — retrogrades, inversions, and transpositions — of this row and its permutations. The twelve-tone technique replaced the implicit order of tonality with an explicit and mathematically determinate order of a different kind. His students Alban Berg (1885-1935) and Anton Webern (1883-1945) extended the technique in contrasting directions: Berg toward a lyrical expressionism that never entirely abandoned tonal references; Webern toward an extreme concentration and economy — some of his movements last under a minute — that anticipated the post-war serial technique developed by Pierre Boulez, Karlheinz Stockhausen, and their Darmstadt School contemporaries.
Igor Stravinsky (1882-1971) took a different path through modernism: not the systematic development of a new compositional language but a series of stylistic reinventions that made him the most protean and influential composer of the century. His early Ballets Russes scores — The Firebird (1910), Petrushka (1911), and above all The Rite of Spring (1913) — brought Russian folk musical materials into contact with extremely advanced harmonic language and a rhythmic ferocity that was genuinely unprecedented. The premiere of The Rite of Spring in Paris on May 29, 1913, provoked what may be the most famous audience disturbance in concert history: whether the uproar constituted a full-scale riot, as legend holds, or a more limited but genuine confrontation between factions of the audience, the event crystallized the rupture between avant-garde artistic ambition and public expectation that would characterize the century's serious music. Stravinsky subsequently moved through neo-classicism — reinterpreting Baroque and Classical models through a modernist lens — and eventually adopted twelve-tone technique late in his career, a final reinvention that surprised everyone who had understood him as a systematic anti-serialist.
Claude Debussy (1862-1918), working in Paris and drawing on the symbolist poetry and impressionist painting of his immediate cultural environment, created a musical language of color and atmosphere that avoided both the structural weight of German Romanticism and the systematic abstraction of Schoenberg's atonality. By using modal scales, parallel chord movements, the pentatonic scale borrowed from non-Western traditions, and the whole-tone scale, Debussy created harmonic surfaces that floated free of tonal gravity rather than straining against it. His Prélude à l'après-midi d'un faune (1894) — a fluid, sensuous orchestral movement based on Mallarmé's poem — is sometimes cited as the first distinctively modernist work, predating the more violent ruptures of Stravinsky and Schoenberg. While European art music fragmented through these competing experiments, a parallel and equally consequential tradition was developing from African American musical culture in the southern United States. Jazz emerged from New Orleans around 1900, combining West African rhythmic practices, blues melodic language, and European harmonic vocabulary into a new improvisational tradition that would reach Chicago and New York in the 1920s and would, by the 1930s, become America's dominant popular music — carrying its own tradition of formal innovation entirely separate from the European avant-garde that was simultaneously transforming the concert hall. The American minimalist movement, emerging in the 1960s through the work of La Monte Young, Terry Riley, Steve Reich, and Philip Glass, offered yet another alternative to European serialism: an aesthetic of gradual change, repetitive rhythmic structures, and consonant harmony that drew on Indian classical music, African drumming, and rock as much as on the European tradition. Reich's Drumming (1971) and Glass's Einstein on the Beach (1976) established minimalism as the century's most publicly accessible avant-garde movement, eventually crossing over into pop and film score contexts and influencing artists from Brian Eno to Arvo Pärt to Max Richter. The twentieth century's classical music, in sum, was not a single tradition but a multiplicity of coexisting and competing traditions, each representing a different answer to the question of what music should do and who it should speak to after the collapse of the shared tonal language that had unified European music for three centuries. The post-war era also saw the rise of musique concrète — music composed from recorded sounds of the real world, manipulated through tape editing and speed variation — pioneered by Pierre Schaeffer at the Radio Diffusion Française in Paris from 1948 onward. Karlheinz Stockhausen extended this into electronic music proper, composing directly with electronically generated sounds in Cologne from the early 1950s; his Gesang der Jünglinge (1956), combining the processed voice of a boy soprano with electronically generated tones, remains one of the landmark works of the twentieth century. John Cage, working in New York and drawing on Zen Buddhist philosophy, extended the avant-garde beyond composition itself: his 4'33'' (1952), a notated piece in which the performer plays nothing for four minutes and thirty-three seconds, proposed that all ambient sound in a performance space constitutes music if the frame of attention is present — a conceptual gesture whose implications for the definition of music are still being worked out seven decades later.