In chord progressions like I - iii - IV - I64 - V - I, which occurs extremely frequently, the IV chord is sometimes replaced by a V6/V, V65/V, or viio/V chord. Regardless they are secondary dominant / leading-tone chords, they appear to have subdominant (predominant) function. Why?

  • 1
    To clarify: is your question asking why the harmonies IV, V6/V, V65/V, and viio/V can all have predominant function?
    – user48353
    Apr 18, 2019 at 4:18
  • @replete // Yes.
    – user53472
    Apr 18, 2019 at 4:19
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    Any harmony which is expected to resolve to the dominant has predominant function. All these harmonies are therefore predominant by definition. I'm not trying to play word games, I'm trying to get to the bottom of the question. Is the question, then, how these harmonies came to have this function, historically? If so, I would look at the voice leading.
    – user48353
    Apr 18, 2019 at 4:22

1 Answer 1


All the above chords emphasize scale step 4, perhaps sharpened. The path 1-4-7-1 seems to be common through many pieces; actually, the pattern of scales steps 4, 7, and 1 often marks a cadence of some sort. (These scale steps need not appear in the same voice.) While I tend to think that most music patterns are learned (cultural), it can be noted that scale playing scale steps 4 and 7 (in a major key) does mark that scale uniquely.

The I64 chord (in this case) is often analyzed as 5 in the root with passing 3 and 1 scale steps is part of a cadential cliche (I64 to V7).

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