Since musicians placed one note atop another it would seem the Western musical tradition has adhered to a traditional functional harmony, a governing doctrine that putatively shaped the definition of Western music until its upheaval in the early 20th century. Harmonicity is present when the vertical pitches are intended and/or perceived as having a functional relationship to one another and these stacks within the morphology of the horizontal continuum. In Western practice this involves a traditional hierarchy based on Pythagorean relationships. The 20th century saw the systematic dismantling of this tonal system that dethroned its putative status in Western music allowing music to expand to some lengths that treat tonal elements as ‘not applicable’.
The doctrine remained at the beginning of the 20th century that composers built a continuum by drawing consonance and dissonance from chordal relationships and tonal gravitation to create tension-relief based morphology. Like all art forms music over time had undergone stylistic development prior to the 20th century by which time musicians’ treatment of tonality had far forgone baroque diatonicism and the syntax of functional harmony was ‘loosened to the point where at best, the felt probabilities of the style system had become obscure’ (Meyer 1967).
Viennese composer Arnold Schoenberg was the first to meaningfully experiment with the notion of dispensing with traditional tonal principles altogether (Rudolf 1978), with categorical success as a result of his twelve-tone technique, of which often-cited examples include his String Quartet No.3 Op.30 (1927) and his Concerto for Violin and Orchestra Op.36 (1936). Simply yet satisfactorily speaking, this involves producing a ‘tone-row’ of which can be repeated until all other notes of the chromatic scale have sounded nor sounded more often than any other note. In developing the twelve-tone method Schoenberg was able to systematically dismantle the traditional and, with respect to intention, hitherto inescapable tonal inclinations of Western harmonicity and create a music who’s individual tones are mutually impartial to one another.
Despite being commonly understood devoid of traditional tonality, Schoenberg opposed the definition ‘atonal’ with respect to his compositions, stating "The word 'atonal' could only signify something entirely inconsistent with the nature of tone... to call any relation of tones atonal is just as farfetched as it would be to designate a relation of colors aspectral or acomplementary. There is no such antithesis" (Schoenberg, 1978). Schoenberg and his contemporaries in the Second Viennese School developed tone rows through serial methods to which future composers applied further musical dimensions such as rhythm and dynamics that had previously remained at the discretion of the composer. One might assume Schoenberg regards the definition “atonal” as better suited to a piece such as John Cage’s Water Walk (1960) which contained no tonal element at all.
As the fundamental underpinnings of Western music were gradually handed to serial outcomes rather than the judgement of a musician the putative understanding and putative identity of western music could collapse. For a number of composers such as Cage, this meant allowing the philosophy behind composition to dominate without the distraction of aesthetic elements, a doctrine that was on of the most important shaping factors of 20th century music.
Meyer, L. B., 1967 Music, the Arts, and Ideas: Patterns and Predictions in Twentieth-Century Culture, University of Chicago Press, Chicago
Rudolph R. 1978, Tonality, Atonality, Pantonality: A Study of Some Trends in Twentieth Century Music, Greenwood Press, Westport Conn. USA
Kennedy, M., (1994) The Oxford Dictionary of Music - "Atonal", Oxford University Press, Oxford & New York
Frisch W, (1999), Schoenberg and his world, Princeton university press, New Jersey. Hollingdale
Ashby, A (2001) Schoenberg, Boulez, and Twelve-Tone Composition as “Ideal Type”, Journal of the American Musicological Society, Vol. 54, No. 3, University of California Press, pp. 585-625.