I'm going through this video: "How to write a MODAL chord PROGRESSION (that sounds modal)", which is very interesting, but at a certain point it refers to:

a. Modal Tonic Chords - chords that are built on the tonic note (I III VI), and

b. Modal Cadence Chords - chords that stray away from the modal tonic (II IV V VII)

Now, if (a) means tetrads that contain the mode root, that would really be I, II, IV and VI, wouldn't it? For instance, D dorian would be Dm7, Em7, G7, Bdim - they have the note D in them.

Or, modal tonic chords are another thing? Searching online didn't clear that up for me.

  • 2
    What leads you to believe they're tetrads? Typically, without explicitly designating seventh chords, the assumption would be triads.
    – Aaron
    Commented Aug 22, 2022 at 20:42
  • Yeah, it was just an assumption. If we were to consider triads, it would be the I, IV, VI, still not the I III VI proposed in the video
    – helil
    Commented Aug 22, 2022 at 23:03
  • 1
    Now that I look at the video, he is talking about 7th chords. They're displayed a few seconds into the segment you timed to.
    – Aaron
    Commented Aug 22, 2022 at 23:46
  • 1
    And I agree with you — I'm not sure where he's getting I, III, VI rather than I, IV, VI. Regarding the exclusion of the II7 chord, my suspicion is that since chordal sevenths are generally expected to resolve, he's not counting the tonic note when it appears as the 7th in II7, since it would be heard as a dissonant note rather than part of a stable triad.
    – Aaron
    Commented Aug 23, 2022 at 0:00

2 Answers 2


My understanding of what he says is:

  1. III and VI chords are closely related to I, as a triad built on III is three top notes of I⁷, and a triad built on VI contains 2 notes of triad built on I.

  2. chords built on II, IV, V and VII have much less in common with I.

Note that in classical harmony the interpretation is very similar. Chords built on III and VI are often interpreted as forms of tonic. Chords built on II and IV are typically subdominant, and V and VII are dominant.

Especially the perfect fourth is typically considered a note causing a strong tension with respect to tonic. This is why II⁷ and IV or IV⁷ chords are not tonic, even if they have some notes in common with I triad.


Music analysis is more often than not a socio-cultural study than a scientific one. We are conditioned to hear certain things the way we hear them, the leading tone screaming to land on the root note of a key after a certain sequence of notes through a major scale for example. Modal music as it (theoretically) first appeared and was well documented, was sung around a root note. Centuries later some people (Jazzists) used random chords, play spicy modes on top of them and call that modal music. Where's the science on that? Hard to establish any logical explanation other than "it worked like that at that time". Although other predominantly "tonal" composers did the same, just not as much and as freely as the Jazzists. See Chopin's Mazurkas for plenty of examples of scales having certain notes altered (raised or lowered) for the sake of introducing a different color to that moment, but not really losing the whole sense of a tonal center driven/given by functional harmony foundations. Context and how melodic and harmony materials are utilized have a stronger say than any attempt to bring mathematical precision into explaining why certain things are the way they are. However, maths can explain even that... but that is another story.

  • 4
    This both fails to answer (or even address) the question and demonstrates a significant lack of understanding of modal jazz. It also demonstrates a limited knowledge of modal chant, which did not revolve around a root — it revolved around a "reciting tone", which would eventually evolve into what is now the "dominant". The modern "root" corresponds to the modal "final".
    – Aaron
    Commented Oct 13, 2022 at 6:04

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