Is there a traditional way to approach other modes functionally, like your pretty functional harmony chart, or some alternatives? I believe I am to understand that our study of functional harmony is derived from the major scale (Ionian mode). Is there merit to using the same functional harmony chart, but starting on a different degree of the scale (aka in a different mode) to create a chord progression in that mode? I realize that in several cases, the seventh scale degree will not lead to tonic as strongly, but in those cases, I could modify the leading tone (a la harmonic minor) if I intended to create a stronger cadential feeling. Do you have any suggestions where to look to study how composers use other modes?
This is a good question. I think it is important to remember that the modes as we think of them originated prior to functional harmony being codified or really even used at all. Prior to this, counterpoint was the rule, and even earlier, the sound of the individual melodic intervals. So it is difficult to say if there is a syntax of modal harmony in the same way that there is a clear syntax with the major-minor system.
That being said, I think you will find that using a mode with the chart, in lieu of a major or harmonic minor scale, will give similar results in terms of syntax, but with less feeling of closure (at least to western ears). Part of what makes modes attractive nowadays is their lack of syntax. You can get away with certain harmonic progressions without violating expectations as much.
I was doing some experimenting with it, and I want to update you and anyone else who reads this on my trials.
I found that using the functional chart tends to work, though, as you say, the other modes don’t resolve the way we are used to.
Another strategy I found that works really well is to emphasize the tones that depart from our accepted Ionian/Aeolian scales. So if I precede the “Tonic” (for our purposes) with a chord that uses those tones, it sends a very cool “Modal Message”. For example, in C Lydian, the F# is the tone “out of place” and I should emphasize it in my harmonies. So functionally I can use V, vii (minor, not diminished), and II# as options for “dominant function” to make a “Lydian” sound.
I also found that establishing the REPEATED return to C in the Lydian mode calibrates the ear to expect it. Normally when I move from C (I) – D (II#)- G (V, effectively tonicizing G) – C (I), it sounds like I’ve stopped on the 4th degree. But as long as I do that repeatedly; using, texture and rhythm strategies you’ve described to tell the listener where they are in the temporal scheme of the music; treating C as the Home key, the ear will accept it as the convention.
Lastly, I’ve just used the Beethoven Quartet 15 Adagio Lydian to model the finale of a choral piece I’m working on (thanks for that, btw, at the Symposium). I found that moving to the Lydian mode in the key (the piece is in Eb, so I’m using Ab lydian), the very much sounds to the ear like a “standing on the dominant” section mixed with a Coda section. Since the rest of the piece used traditional cadences, this section builds tension similarly because of the repeated, “unresolved” return to the Lydian home chord. And I think we’re used to hearing the 4th degree in Codas. So it’s more like standing on a Plagal “dominant” (if that can be a thing).