Locrian Harmony

Question

I like utilizing modes in my the pieces I write, but there is one mode I've never been able to fully grasp and utilize and that is the Locrian mode.

The chords that naturally occur in the Locrian mode don't seem to lend themselves well to any chord progression that implies the tonic especially since the tonic chord itself is diminished and is perceived by most to be unstable.

So when composing in the Locrian mode, is it possible to create a chord progression that leads back to the tonic convincingly and if so what are the concepts behind it and what should one look for?

Answer 1

I think, Dom, that you would need to do a few things:

1. Truncate the tonic - it will always be root and third. (This kind of truncation wasn't all that unusual in late Renaissance and early Baroque modal polyphony, by the way, even though the Locrian mode itself wasn't used at all.)
2. Borrow procedures from the Phrygian mode, which is the closest in intervallic structure. ♭vii⁶-i cadences (Phrygian cadences that feature the descending leading tone, ♭2, in the bass) are going to be common. Other cadences (iv-i or II-i) are going to be touchy because the ♭6 will want to fall, but will usually need to rise instead because of the mode's ♭5. Augmented sixth chords based on ♭vii⁶ will work well.
3. ♭6 is going to be the mode's tenor (melodic quasi-dominant), again because of ♭5.
4. Similarly, from a harmonic point of view, you will most often move to ♭VI for imperfect cadences, because the chord with root on ♭3 is not a relative major (that's to say that it is ♭iii, not ♭III), and v or V pretty much ruins the mode.
5. It's probable that you will occasionally sharp ♭5 when rising to ♭6 (in ♭III-♭VI progressions, for instance). You may well also do so if you end with a tierce de Picardie, i.e., ♭vii⁶-I.