Naming the Dissonance - a brief infordump

Hello, dear reader. Are you musically adept or nerdy? I was just asked about minor seventh chords by a performer who found the structure confusing. Most of my writing regards philosophy, being human, awakening to the momentum of stories and lies in our culture, questioning our assumptions, knowing our values, and getting over ourselves.

But sometimes, we find an insatiable beauty in a question that arises when we do question our knowledge. And I can hardly resist a setup like that.

So, as a composer who speaks music pretty darned fluently, here’s my answer.
Seventh chords matter because of the stacks of thirds in them. These are categorized for digestibility by humans (as with most of our knowledge - take time, for instance… that’s just a way to organize what we think we know.) But if you care, seventh chords can cause you to scratch your head.

Seventh chords exist in western scales and in modes because of the steps inherent in those organizational pillars of the musical language. Some exist more as theory in name, and as exquisite modulation points and tension points in use. I rarely think about the types of chords I’m using because I write in flow and hear the language of music, not the language of English describing music.

Still, here is a breakdown of what exists theoretically in name. There are more seventh chords than mentioned in the question, largely because there are more possibilities relative to the stack of four pitches rather than stacks of three.

M7 - root, M3, P5, M7 (Major seventh)

mM7 - root, m3, P5, M7 (minor Major seventh)

+7 - root, M3, #5, m7 (Augmented minor seventh)

m7 - root, m3, P5, m7 (minor seventh)

m7b5 - root, m3, d5, m7 (minor seventh flat five)

M7b5 - root, M3, dim5, m7 (Dominant Seventh flat five)

dim7 - root, m3, d5, d7 (diminished seventh)

The first stack of thirds is MmM, then mMM. These two each stack to a Major 7 interval. It is worth noting that M7 is actually dissonant because pitches, such as we name them, are cyclical.

The next stacks of thirds are mMm, then MMdim, then mmM, then Mdimm, each stacking to a minor 7 interval.

Finally, the dim7 chord is mmm, and stacks to a diminished 7 interval.

Now for what I love. dim7 chords are delicious, in my opinion. Theorists call them more dissonant, but I disagree; there are levels of dissonance to every seventh cord. A unique property of the dim7 is that there are only three of these stacks possible, with the fourth stack in any series being a repetition of the first stack.

This is what gives them their unique, modulate-on-a-dime quality.

Who else plays around with seventh chords?

Leave me a comment. Crickets are nice, but I love your comments.