I saw someone make the vague claim that in Debussy you can often identify passages with predominant function, even if they don't represent chords that are typically considered predominant chords. I realized that, as far as I can tell, there's no single scale degree, pitch class, or interval movement which identifies a chord has having predominant function (unlike dominant function, which is arguably defined by leading tone to tonic or a tritone resolving inwards). Some predominant chords look exactly like standard dominant functions applied to chords which actually have dominant function in the tonal context, like V/V, but other predominant chords do not. In addition, it's even more complicated in instances like Debussy where there are totally nonfunctional passages, in which case obviously not being tonic or dominant does not necessarily imply predominant function. What criteria can I use to identify a chord as having predominant function?

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    Use the only criterion that matters for anything in music theory: It's a predominant if it sounds like a predominant. Otherwise, it's not.
    – user19146
    Aug 12, 2018 at 19:46
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    alephzero - please don't take offense at this, I'm genuinely curious: What are you trying to contribute in your comment? Are you working with the assumption that many people have a strong enough idea of what predominant function is that they would recognize it, but doubt themselves because of their lack of understanding of the point of music theory? Maybe this is the case for some people, but, speaking for myself, I don't already have a clear idea of what predominant function sounds like, so I can't "just see if it feels predominant"
    – lightning
    Aug 14, 2018 at 15:19
  • you seem to use subdominant and predominant in your question. are they the same thing? Aug 17, 2018 at 18:06
  • Agnes - whoops, edited! My understanding is that predominant is a general term for a harmonic function while subdominant refers to chords based on the fourth scale degree
    – lightning
    Aug 17, 2018 at 22:04
  • Tonic function: - I i - iii III+ - vi VI Subdominant <sup>(or Predominant)</sup> function: - ii ii° - IV iv Dominant function: - V V - vii° vii°
    – user53472
    Jan 17, 2019 at 13:47

3 Answers 3


First, I think any attempt to understand functional harmony will be frustrated by using examples from Debussy! I don't mean there isn't functional harmony in Debussy, but a key element of his style was non-functional harmony. Composers like Bach, Handle, Mozart, or Haydn will provide much clearer examples of functional harmony.

Various textbook offer up various harmony progression 'rules' or conventions. But, I think this sums up the basic functional idea...

tonic > (pre-dominant) > dominant > tonic

  I   >       (x)      >     V    >   I

A pre-dominant chord must be optional or else the definition wouldn't fit any actual music.

I used and 'x' as a symbol for the pre-dominant to show many chords can be used, it isn't realistic to say any chord can be used. For starters it categorically should not be a I or a V, because those are the chord for the other two functions.

Now we get to an interesting point. The three function are different in the number of chords that fulfill the function:

  • tonic : really just I. I suppose someone will say vi for a deceptive cadence, but I would disagree as the whole point is the deception is because of the non-tonic identity of the cadence chord.
  • dominant : the V or viio chords with leading tones. (Regarding other scale degrees: despite the function name, the ^5 scale degree, the dominant, may not appear, like in the case of viio, except for the dominant, no other tones from the tonic chord should appear, therefore iii is not a dominant despite the leading tone being in the chord.)
  • pre-dominant : lots of chords...

If saying 'any chord not a tonic or dominant is a pre-dominant' is a problem, then typical textbook harmony would give something like...

  • categorically exclude I, V, and viio, what remains will be...
 ii    iio   bII   Fr+6
 iii* bIII**
 IV    iv     It+6 Gr+6
 vi   bVI

Those would be the typical pre-dominant chords. Inversion and seventh chords aren't enumerated.

(*) iii contains the leading tone, but doesn't function as a dominant meaning it doesn't lead to a cadence on I, normally it would go to vi

(**) bIII might not lead to V normally and could be part of a modulation from minor to relative major, or might just lead to bVI

(***) minor dominant doesn't have a leading tone, doesn't form a cadence to i or I.

Some don't like prescriptive lists of harmony in which case I suppose the '...any chord...' definition will work.


'Pre-dominant' isn't a precise term. You'll find it applied to just about any chord that isn't a tonic and which precedes a dominant.

Obviously such terms have no relevance in "totally nonfunctional passages".

  • According to en.wikipedia.org/wiki/Predominant_chord, especially its third source, a predominant chord resolves directly to a dominant chord. It's possible that "predominant" has more than one accepted definition.
    – Dekkadeci
    Aug 18, 2018 at 0:03
  • A definition is only as good as its usage!
    – Laurence
    Aug 18, 2018 at 10:51
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    @Dekkadeci. That Wiki definition has the same meaning as Laurence's answer, except that Laurence's is better, because it includes the obvious necessary exclusion of the tonic chord. Jan 17, 2019 at 14:21
  • @MichaelCurtis - I got the impression from the Wikipedia article that predominant chords do not resolve to anything other than dominant chords and secondary dominant chords. (Chords that can be predominant chords (e.g. IV, ii7) are able to resolve to other non-tonic, non-dominant chords, but at that point, are they called predominant chords?)
    – Dekkadeci
    Jan 17, 2019 at 16:28
  • @Dekkadeci, I think that is a different question. Might be worth posting a new question, because it needs elaboration. I-IV-I a tonic prolongation. Is that IV a pre-dominant? I would say no. But if someone wants to yes, because eventually I goes to a V. Well, OK call it pre-dominant if you want. Jan 17, 2019 at 17:22

Pre-dominants make much more sense in a diatonic context. It's tricky with Debussy where sometimes he doesn't have a clear tonic to begin with (i.e. the whole-tone stuff). But roughly speaking, my understanding is that a pre-dominant is a chord that typically precedes the dominant. If someone plays a piece up to that chord and asks folks to sing (arpeggiate) the next chord, they'll sing a dominant. This can be V/V for sure, but also typically ii or vii. Even vi (or VI) is sometimes considered pre-dominant but usually I think of a pre-dominant as being free of the tonic note, unless it's a ii7.

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    "usually I think of a pre-dominant as being free of the tonic note, unless it's a ii7" - I thought IV was the prototypical predominant?
    – lightning
    Aug 18, 2018 at 19:30
  • One would think, but because it's a "subdominant," it's in its own category. Aug 20, 2018 at 3:37
  • "pre-dominant as being free of the tonic note..." that would mean the IV chord can't be a pre-dominant, but that doesn't make sense. A much better rule of thumb regarding scale tones would be pre-dominants will not contain the leading tone. Jan 17, 2019 at 14:27

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