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:
A whole-tone scale is just that: only whole steps, not a half step to be seen. Why does the use of this scale undermine common-practice harmony and tonality?

Post your reply and come back Friday, March 25th for the answer!
ANSWER for 3/7/22
Great comments on this week’s challenge! Common-practice harmony is centered around major-minor tonality. A whole tone scale undermines this because there are no perfect fifths, and so it’s impossible to create major or minor triads with this scale. Only augmented triads can be formed. Also, as Steve, Madison, and Brian said, with no half-steps, there can be nothing resembling tendency tones, the building blocks of common-practice cadences. Patricia and Robert correctly pointed out that there’s no sense of resolution, and that each chord sounds as much like a tonic as any other.
Because of this scale’s intervallic symmetry (based only on the whole step), it has been called a mode of limited transposition by French composer Olivier Messiaen. It can only be transposed once before repeating the same pitches, and so there are only two whole-tone scales. In the late 19th-Century, along with octatonic scales and a renewed interest in the old church modes, the whole tone scale was one of many tools that circumvented, and ultimately undermined, the rules of the common-practice.

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No minor seconds means no leading tones. No leading tones means no cadences.
There is not a pull to any tonal center because of the lack of half step pull.
Common practice (i.e. 18th/19th European music) is based on the progression of dominant to tonic. The whole tone scale does not have a dominant. The leading tone is pretty important, but it’s really the movement of dominant resolving to tonic. Even as late as Wagner’s Liebestod the harmonic direction was towards the dominant (which eventually resolves to the tonic).
An extra comment…. The whole tone scales doesn’t really destroy tonality while obscuring the dominant. When Debussy uses the whole-tone scale, it is not really atonal because it still had a concept of tonal center, but it does eliminate the emphasis of a dominant.
Absolutely, you can still have a sense of tonal center with a whole tone scale, but it’s far less convincing than if you have common-practice harmonic progressions at your disposal. So, while not destroying tonality, it certainly was one of many tools that weakened it.
Such knowledgeable answers. My thinking was that the scale doesn’t lead to a sense of resolution. It seems to just continue on without a place to stop ie resolve. As a singer it would be difficult to sight read music without chords and tonal relationships to support the ear.
There is no tonality with a whole tone scale; there is no key. A whole scale on f is the same notes as one on g and as one on a and as one on b… All the notes are equally important. There is no key note.