Show off your theory chops with my weekly challenge! You’ll find a new question here every Monday. Please comment to post your reply.
This Week’s Challenge:
The late 19th-Century saw the rise of musical nationalism in Europe. Composers in Bohemia, Hungary, Russia, and, to some extent, in France wanted to liberate themselves from common-practice styles and rules, which were largely of German and Italian origins. So Smetana and Dvorak, Glinka and the Mighty Five, and later Bartók and Debussy set about using resources that predated major-minor tonality–the cornerstone of the common practice. They often reached back into their own folk music, which relied heavily on the old church modes: Dorian, Phrygian, Lydian, and Mixolydian.
So here’s the challenge: how do these modes help to undermine common-practice tonality? There doesn’t have to be one correct answer!

Post your reply and come back Friday, May 13th for my take on it!
ANSWER for 5/9/22
While renewed interest in modes wasn’t the only factor in the dissolution of common-practice tonality, it certainly helped. For me, the best example is Mixolydian, identical to a major scale except for the lowered seventh degree. This makes for a minor dominant triad, with which a typical authentic cadence is not possible. Other modes generate similar harmonic colors that, while beautiful and compelling, destabilize the primacy of the V-I relationship. Moreover, the growing reliance on color to carry a piece (rather than harmony, melody, or rhythm) became yet another rival to established common-practice rules. The purpose of tonal harmony is movement: tension and resolution driving the music toward a goal. With the lush, often modal soundscapes of Debussy, harmony has a very different function: immersion.
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