6. Chord Context
Every chord can serve several potential harmonic functions, and is context dependent. Identifying the correct function of a chord allows us to understand the harmonic move or pattern it serves.
Every chord has 4 types of context:
1. Diatonic context (= the major / dominant scale it is on).
2. The scale of chords it goes with. To find it, identify its 6-chord variation (see six-chords chapter) + the diminished chord that goes with it (a half-step below the six-chord).
3. The family it belongs to (i.e. the diminished chord it comes from. See Family chapter).
4. Its function within the harmonic pattern (e.g: is it a ii in a ii-V-I? the I? the V? leading to the I, ii, or V? etc.).
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▪ Dominant chords are on 2 scales: their own dominant scale and the major scale of their relative I (the dominant being a V, the major being the I).
▪ Major chords are on 2 scales: their own major scale and the major scale on its V.
▪ Minor 7th chords are on 3 scales: a major scale a whole step below, a major scale 2 whole steps below, and a major scale 3 half steps above. To know which of the 3 major scales it is on, identify the tonal center in which it appears. That is the one.
The notes of a minor 6 chord are technically on a major scale, but we refrain from relating to this major scale as its context. The minor 6 chord should be seen in the context of the dominant it substitutes (as we saw earlier, a m6 can substitute a dominant chord, E.g: the context of a Cm6 chord is on the 5th scale degree of an F dominant scale).
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A minor triad chord can be viewed as either a simplified m6 chord or simplified m7 chord (context dependent).
A major triad chord can be viewed as a simplified M6 or M7 chord, not a simplified dominant chord.
m7♭5 chords are either inversions of a m6 chord or a m7 chord with a flatted 5.