Here's Soma by The Strokes. If I'm not mistaken, the verse progression moves simply from a G chord to an F chord repeating. If the key is C, then this is just V-IV-V-IV etc. Since the chords are only moving by step, there is no interesting root movement, (descending fifth or ascending forth, for example) yet there is still something nice about the sound. Additionally, there aren't any common tones between the IV and V chords, so the voice leading isn't crazy smooth or anything. Why does this work?

  • Well, it's been working for at least 400 years already. There were popular songs in Shakespeare's day that used exactly the same chord progression!
    – user19146
    Commented Aug 11, 2018 at 8:15

3 Answers 3


As Laurence correctly says, the song is really in G Mixolydian. It uses the same notes as C major (including an F♮), but with G as tonic, it's definitely G Mixolydian. As such, this G to F to G switch is best understood as I–(♭)VII–I.

Explaining why it works is a bit trickier.

Let's think about "classical" music first. In this repertoire, chord progressions of an ascending step are pretty common. I often moves to ii, iii often moves to IV, IV moves to V, and V moves to vi. But chord progressions by descending step are pretty uncommon. Indeed, the only common descending-step progression is vi moving down to V, but even that is relatively rare and only present under particular circumstances.

But then comes popular music, and descending-step progressions are all over the place. I loves to move to ♭VII, then that ♭VII can move to ♭VI, then that ♭VI can move to V, and then that V can move to IV (!). (Let's not even talk about ♭III–♭II–I...)

The point is that it works because it happens all the time in popular music. Perhaps it's ease of playing, since we can often just shimmy our hands two frets down the guitar neck. But ears are so accustomed to this progression that we don't question it; it's as basic to popular music as IV–V is in the Classical style.

  • With the descending steps, it's possibly more common using i instead of I before moving down to bVII.
    – Tim
    Commented Aug 12, 2018 at 14:42

Yes, it's the notes of the C major scale. But it's pretty obviously centered on the G major chord. Listen to the ending. That's definitely a tonic chord, isn't it! So we need a 'theory' that allows a G chord and an F chord without being 'in the key of C'. We could label it as 'G Mixolydian'. Quite common in pop music, as well as historically.

But that just labels it. It doesn't tell us WHY it works. And that can be a hard question. Sticking to one scale 'works'. But mixing scales 'works' as well. Moving by step 'works'. But so does moving by fourths, fifths, minor thirds...

Welcome to 'theory' as a descriptive art, not a prescriptive one. 'Theory Describes, It Does Not Command'. Add this to your list of 'things that sound good'. Discard any 'theory' that tells you it shouldn't.


Two Consecutive Major Chord can be only IV and V. Thus the tonic here must be C.

A bold guess but if you would transcribe the melody it would be in C major.

  • 1
    No. You're trying to force the chords into being diatonic in a major key. They aren't.
    – Laurence
    Commented Aug 12, 2018 at 9:31
  • Honestly, I haven't even listened to the song. That's a mistake. I've got somewhere a long printed list of popular chord progressions and the corresponding songs, and many of them don't contain the tonic. Also, a whole band keyboard, bass etc. almost never plays pure triads. If I really want to do something with a song I get down the melody to a paper. Now I've listened to the "Soma" following the melody with a guitar. It is definitely in G major as you said. ( I've learned the lesson, I should have started with this.)
    – TwoFiveOne
    Commented Aug 12, 2018 at 10:57
  • Well, it's in G something! Some would say it's in G major, and not get hung up on the use of bVII. Some would describe it as G Mixolydian. But it certainly isn't in C. It's possible that your list of 'songs sans tonic' are in the same category.
    – Laurence
    Commented Aug 12, 2018 at 14:28

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