Why did Arnold Schoenberg create his 12-tone system?

Answer 1

He was looking for a way to advance music by freeing it from the bonds and restrictions of tonality, the basic idea that a piece of music can have a tonal center, or progressions of tonal centers. Most western musics still produce works with tonal centers, and they can be identified if you can correctly determine that a piece is written in a certain 'key' or with some other organizational system that allows for harmonic progressions or tonal bias of some kind. This means that the music will tend to contain harmonies that are consistent with tonal concepts (or music written in keys) and the music will generally tend to resolve itself into a final key. Schoenberg's system attempted to use all of the 12 standard tones equally and without bias toward standard concepts of harmony. As it turns out, this is nearly if not literally impossible, and many composers even made creative use of harmonic ideas within their 12-tone works.