My theory of harmonic functions

[fmr]

Regarding the vi and vii degrees as "key factors of the harmony", I don't agree much. The vii degree has not much use as it is a weaker chord and is contained in the dominant 7th. In four-part chorals or part-writing in general it may sometimes be used, when we seek for a weak cadence. But "weak" is the key word here.

First, I'm under an impression here that we are talking of different things here. I was referring to the 6th and 7th degrees of the scale (the notes, hence the arabic numerals) while you seem to be referring to the chords built on this degree. Given that, I assume that our arguments are disconnected here (or, if I'm wrong, please correct me). I would still like to give a few comments to your thoughts.
To me personally, root-position vii has a way stronger dominant feel than V, at least as long as we talk about triads. Probably it's also stronger than V7, unless V7 is in the first inversion, but then root position vii7 is even stronger. YMMV

Yes, I was talking about the chords built over those degrees. The vii degree is included in the V (dominant) chord, as well as in the I7 (7 chord built over the I degree), the chord built over itself (diminished fifth chord or vii chord) and also the chord built over the iii degree (minor chord).

Despite this, only the V (dominant chord) and the diminished vii chord attract the I chord (therefore have a "dominant" feel, following your terminology, I certainly don't feel any attraction when using the iii chord, nor the I7 chord,

personally, root-position vii has a way stronger dominant feel than V, at least as long as we talk about triads. Probably it's also stronger than V7, unless V7 is in the first inversion

Let's agree to disagree. the diminished chord over the vii degree is usually used in the first inversion, and sometimes leads (is followed by) the V7. You rarely see it in its fundamental (root) position, especially in part-writing. And it certainly doesn't feel so strong as the V7 chord, when used in the root position. The jump of fifth in the bass is one of the strongest tonal movements we may have, IMO.

Regarding the vi, it is a modal degree (as is the iii), and although it is more used than the iii, it is used most of the time as a replacement chord for the I. If we are in minor mode, the III degree is more important, as it is the root (I) of the relative Major. When we seek for a twist in the harmony, we may use a chord progression from V to vi (VI in minor mode). The cadence V-vi or V-VI is called "deceptive cadence", or "interrupted cadence". I think it gives you a clue about what's the feeling of moving from the V to the vi or VI, instead of the I. Of course, being a neighbor key (closely related key), and in a different mode, it is a good candidate for tonal change/modulation (with the added advantage of also changing mode from Major to minor or vice-versa), but that's another subject.

First, I'd like to point out that in minor mode VI has a definite subdominant feel to me, but you seem to be primarily referring to the major mode. In major mode I agree, the subdominant feel of vi is strongly overridden by its function as the tonic of the relative minor (because the relative minor is so prominent). However IMHO this feel is still there, and becomes more prominent in the deceptive cadence you mentioned or in the downwards root movement by thirds: 1-6-4-2. Notably, to me minor mode progressions V-VI and V-iv sound very similar, and there is a similar, although weaker similarity ( ) between major mode progressions V-vi and V-IV. The things get different in harmonic major, though Similar argument applies to what you said about III (esp. if the 7th is raised ).

No arguments against the first part, but I have to confess I disagree regarding the similarity between V-vi and V-IV in Major mode. And you completely lost me in the next phrase (???) I did not understood what you were talking about (iii with the vii raised? That's an augmented fifth chord - it doesn't work very well in this, IMO)

In minor mode, the seventh built over the raised vii degree creates a diminished seventh chord. This chord is a symmetrical one (all intervals are minor thirds) which makes it the ideal pivot for quickly modulating to distant tonalities (any note of the chord can be considered as the leading tone of the new tonality). Therefore, it has more use and more importance then the seventh built over the vii degree in Major mode (leading tone seventh).

Maybe, but this is a bit disconnected from what I have been talking about (the dominant or subdominant feel). Personally to me the diminished seventh chord on the raised 7th is probably the one with the strongest dominant feel of all chords. Again, YMMV.

PS. Just noticed that, while in minor the dominant feel is made more prominent (or becomes present at all, depending on how you see it) by raising the 7th degree, in major the subdominant feel is made stronger by lowering the 6th degree.

Yes, raising the vii is absolutely necessary if you want to work with the minor mode harmonically (that's why it is called "harmonic minor". If you don't do this you will not have the attraction necessary for the dominant function to work, and the minor mode becomes kind of "modal".

The diminished seventh over the raised vii is a strong chord, no doubt, because it adds the minor third and two strongly attracting intervals - the diminished fifth and the diminished seventh. But, besides that, it works very well to twist the harmony, by resolving in another tonality, which, due to its symmetry, works also very well.

[Z1202]

I feel that the disagreement may come, at least partially, from two different aspects:
- the kind of music (and, as I mentioned, I'm mostly, although not necessarily, targetting something like pop music of the late XX century)
- more importantly (and this is why I changed my terminology from "function" to "feel") is that I'm more interested (for the purposes of this proposal) in the static sound of the chord (hence "feel") rather than where it wants to go ("function"). In that regard e.g. the raised 7th has, from my POV, more impact on the static feel of the chord, compared to the presence of the 5th degree in the bass.