4 for IV, Part II: IV Chords & Tonal Ambiguity/Modulation

In Part I of this series, I examined the secondary plagal progression, which is a unique way in which rock/pop composers have extended the established sound of a IV-I plagal progression. Another common technique that demonstrates the evolution of the IV chord is the incorporation of tonal instability through its presence in a harmonic progression. Generally, rock/pop music is not lacking for a tonal/modal center. However, some songs use the comforting and predictable sound of a plagal progression to introduce either tonal ambiguity or a full-fledged modulation.


Green Day, “Warning”


Despite its lack of overdriven electric guitars, “Warning” is very much a prototypical Green Day song because it only uses three different chords the whole way through. Yet these three chords (one of which is a secondary plagal chord) present an unexpected analytical challenge that lends a subtle sense of ambiguity to the song’s tonality.


Except for the song’s bridge and start of its third verse (which both simply vamp an A chord), the entire song uses the following progression. For those not familiar with my notation, vertical lines indicate barlines, diagonal slashes between chords indicate multiple chords in the same measure, and lead-sheet symbols and Roman numeral analysis are provided. I have analyzed it in A Major, but as I will discuss momentarily, that isn’t quite as clear-cut as it might seem:


A (I) / D (IV) | G (IV/IV) / D (IV) |


That’s it. Four chords (two of which are the same), two measures. It seems like a pretty simple pop song, which is largely because it is. But what happens if we think of D as tonic instead of A? Such an analysis would look like this:


A (V) / D (I) | G (IV) / D (I) |


On paper, this makes a lot of sense. Now every chord is diatonic, with dominant and plagal chords alternating between tonic. Adding complication to the matter is that if you listen to the song through the perspective of either A or D being tonic, both kind of make sense.


So why do I consider the song to be in A Major? The main reason is because even though the D chord appears twice as much in the vamped progression, A Major receives a bit more emphasis throughout the song. While D is the final chord of the progression, the progression always starts anew by returning to A, which makes this chord sound like the destination of the progression rather than D. Also fueling this perspective is that the song ultimately ends on A Major. The exclusive use of this chord in the bridge and beginning of the third verse gives considerable weight to this chord, as well. Furthermore, the contour of Billy Joe Armstrong’s melody makes the pitch A seem much more like “do” than the pitch D. Specifically, every phrase of the melody (which is usually the same two-measure length as the vamped progression) ends on the note A, making this pitch sound like the melody’s home.


When understood in A Major, this progression is very similar to the ones I looked at in Part I for The Kinks’ “Celluloid Heroes” and The Go-Go’s’ “Our Lips are Sealed.” All three feature a secondary plagal chord moving to the diatonic plagal harmony, which then moves to tonic. The difference here is that a IV chord also comes between tonic and IV/IV, making the progression more purely cyclic and giving less overall weight to tonic. Because of this, the progression tends to have dual function and invites and understanding of its function in D Major.


Although the argument for A Major is more compelling than that for D Major, at the very least Green Day have concocted a simple, repetitive pop song that is tonally ambiguous, and they achieved this through their incorporation of plagal progressions.


Counting Crows, “Scarecrow”


Appearing on 2014’s Somewhere Under Wonderland, Counting Crows’ “Scarecrow” (named for their arch nemesis?) also presents an analytical challenge through its used of tonal (or, in this case, modal) ambiguity. In addition to primary and secondary plagal progressions, they also use modal borrowing chords to obscure the song’s modality.


I hear this song as being primarily in D Major, largely for the same reasons I gave with “Warning.” Especially important here is the gravitation towards D as “do” in the melody. However, the ambiguity is stronger in this example for reasons I will expound upon momentarily. Here are the specs for the song, as analyzed in D Major:



D (I) / Am (v) |



D (I) / Am (v) | D (I) / Am (v) | C (IV/IV) | G (IV) | (2x’s)

F (bIII) / Am (v)



D (I) / Am (v) | Em (ii) / Am (v) | C (IV/IV) | G (IV) | (2x’s)



Am (v) / G (IV) |



Dm (i) | Am (v) | Bb (bVI, or IV/IV/IV/IV) | F (bIII, or IV/IV/IV) |

C (bVII, or IV/IV) | G (IV) | Bb (bVI, or IV/IV/IV/IV) | F (bIII, or IV/IV/IV) |



Intro (8x’s): 0:00

V1: 0:26

Ch: 0:54

V2: 1:20

Ch: 1:49 (+ Tag)

Bridge: 2:18

V3: 2:43

Ch (2x’s): 3:12

Coda (Verse pattern): 4:03, + Tag (3x’s)


Notice that all of the V chords in this song are minor (v/A minor, not V/A Major). This chord, which uses the lowered seventh scale degree, is an example of modal borrowing, but its consistent presence also means that the song is modal rather than tonal. Specifically, the song is in the mixolydian mode, which substitutes raised scaled degree seven (ti) for lowered (te).


This chord also plays a significant role in blurring the song’s modal center. When A minor is substituted for A Major, C Major (IV/IV) is swapped for C# diminished (viio), and all the other diatonic harmonies of D Major remain, these chords all have diatonic function in G Major. The A minor would be a “ii” chord in G Major, and the secondary plagal C Major would be IV. For this reason, much of the song can be heard as being in either D Major or G Major.


Look at the chorus, for example. Were this progression to be analyzed in G Major, it would look like this:


D (V) / Am (ii) | Em (vi) / Am (ii) | C (IV) | G (I) |


Once again, all of these chords are diatonic, and with the final chord of the progression being tonic, its function in this key makes a lot of sense. In addition to the minor “v” chord’s use here, the appearance of the plagal progression that comes at its conclusion lends credence towards understanding this song in either key. The C-G progression works both ways, and the implementation of this comfortable sound at this crucial point affords them the freedom to be ambiguous.


The song’s bridge adds even further intrigue to this dilemma by maintaining function in both keys while introducing D Major’s parallel minor key as a possibility, as well. Regardless of the key, the progression here incorporates a combination of modal borrowing and sequenced secondary plagal chords (similar to the progression from “Hey Joe”). I chose to analyze this section in D Major to keep it consistent with the other sections, but the first D minor chord’s potential function in the key of G Major is notable. This chord would be the minor “v” in G Major, which creates an interesting parallel with the song’s consistent use of the minor “v” in D Major. Not surprisingly, this unusual progression – which mixes modes freely and could potentially function in three keys – is largely dependent on plagal motion. Of its eight chords, half of them have roots separated by a descending perfect fourth.


The final piece of the puzzle occurs with the final two chords. The song concludes with a short tag that oddly features chords that do not appear consecutively at any other point. This tag is perhaps the strongest argument for the song being in G Major, as this is the final chord of the entire song. In G Major, this would be a ii-I progression, which is an unusual sequence in classical music but not out of place in rock/pop music. Still, it would be a bit odd for a final cadence.


Perhaps the best interpretation of “Scarecrow’s” modal dilemma is that is simultaneously in both D and G Major. I still tend to hear the song as D being tonic, but it is difficult to dismiss G entirely. Especially in the chorus, both D and G carry a workable tonic function. Once again, the use of the IV chord and plagal progression help facilitate this flexibility and allow for an arguably bitonal song to sound organic and even catchy.


Elton John, “Saturday Night’s Alright for Fighting”


Another song that presents an intriguing tonal dilemma is Elton John’s “Saturday Night’s Alright for Fighting”. The song has three main sections plus a short introduction, including what I consider to be two separate choruses. The song is ultimately in C Major, but I have analyzed the verses here to be in G Major (more on that in a moment).


Intro: alternates between G (add A) and G, then F (add G) and F, then C (2x’s)


Verse (in G):

G (I) |   | F (IV/IV) |   | C (IV) |   | G (I) |   |

G (I) |   | F (IV/IV) |   | C (IV) |   | G (I) |   | Dm (v, or ii in C) |   |


Chorus (in C):

C (I) |   | Bb (IV/IV) |   | F (IV) |   | C (I) |   |

C (I) |   | Bb (IV/IV) |   | F (IV) |   | C (I) |   |

G (V) | Eb / D (modal borrowing walk down) | C (I) |   |

G (V) | F (IV) / Am (vi) | G (V) | F (IV) / Am (vi, or ii in G) |


Chorus 2 (in C):

F (IV) / C (I) |   | Eb (IV/IV/IV) / Bb (IV/IV) |   |

Bb (IV/IV) / F (IV) |   | F (IV) / C (I) |   |

F (IV) / C (I) |   | Eb (IV/IV/IV) / Bb (IV/IV) |   |

Bb (IV/IV) / F (IV) |   | F (IV) / C (I) |   | Dm (ii) |   |


(blank measures repeat the chord/chords from the previous measure.)



Intro: 0:00

V1: 0:13

Ch: 0:42

V2: 1:20

Ch: 1:48

Ch2: 2:20

Ch: 2:48

Ch2: 3:19 (w/ vocals added, vamps first 8 measures)


This song can be heard in one of two ways: either the verse and two choruses are all in C Major, or the verse is in G Major while the choruses are in C. I tend to hear it as the latter because the progression ends up being identical relative to tonic this way, and the melody implies that G is tonic for the verse sections. Also, both sections use “ii” chords as their pivot harmonies, which is unique yet used consistently at the end of each section. Each chord in the verse has function in C Major, though, which presents a complication similar to the previous examples.


Nearly every chord is either tonic or some sort of plagal extension. The only exceptions to this are the pivot “ii” chords and the chords in the back half of the first chorus. These chords include a few dominant chords, a couple “vi” chords (though the latter of these serves as this section’s pivot “ii”), and a quasi-modal walkdown into tonic from dominant. All three sections feature progressions constructed around the basic secondary plagal progression (as seen in “Our Lips are Sealed”), but each section’s approach towards embellishing these chords creates a multi-faceted approach to this harmony. The chords in the verse are played without embellishment. During the first chorus, suspension figures are occasionally added, while the suspension figure becomes so prevalent in the second chorus that it implies another layer of secondary plagal chords that is similar to the progression seen in Springsteen’s “Glory Days” (these plagal progressions repeat three times every two measures, but this detail was omitted here for simplicity’s sake). Because of the global similarities centered around these plagal progressions across each section, the use of two key areas comes off seamlessly.


The Talking Heads, “And She Was”


Every example of modulation and/or tonal ambiguity thus far has involved key areas that are a fourth or a fifth apart. This makes sense, as these key areas will have virtually identical sets of pitches with only a single disparity between them. An example of a song using plagal progressions to achieve a modulation to a more foreign key can be seen with The Talking Heads’ “And She Was”, which begins in E Major and then shifts up a half step to F. The fact that these keys are only separated by a half step might make them seem like an organic fit for a modulation pairing, but because the pitches in both scales share little in common (only the notes E and A are used in both), the opposite is actually true.


Verse (E Major):

E (I) / A (IV) | E (I)   | (6x’s – voice enters 3rd time)


Prechorus (F Major):

Bb (IV) / F (I) | C (V) / F (I) | Bb (IV) / C (V) | F (I)   |

Bb (IV) / F (I) | C (V) / F (I) | Bb (IV) / G (V/V) | C (V)   |


Chorus (E Major):

E (I) / A (IV) | D (IV/IV) / A (IV) | (4x’s)


Bridge (b minor):

Bm (i) | Bm (i) | G (VI) | G (VI) | (2x’s)



V1: 0:00

Pre: 0:24

Ch: 0:39

V2: 0:54

Pre: 1:17

Ch: 1:32

Bridge: 1:47

V3: 2:02

Pre: 2:25

Ch: 2:40 (4x’s through)


The modulations from the verse’s E to the prechorus’ F and then back to E for the chorus are both direct in that neither has a pivot chord to facilitate a seamless transition. As a point of comparison, the minor chords that concluded each section of “Saturday” served mutual function in the keys that came before and after them. Here, the tonic E Major that ends the verse jumps right to a plagal Bb, and then a dominant C Major at the end of the prechorus shifts directly back to a tonic E Major.


Because of the disjunctive nature of the harmonic transitions and the relationship of the keys themselves, these would seem to be incredibly dissonant modulations. Yet while the lift from E to F stands out, it still works in the context of a catchy song thanks to each section’s reliance on plagal progressions. In a vacuum, there is nothing too unique about the progressions for each section (although the prechorus uses a secondary dominant, and the chorus uses a secondary plagal – and a progression identical to that of “Warning”), but the use of the sudden modulation brings rejuvenation to these otherwise very basic progressions.


The other notable aspect of this song is its bridge, which features a modulation to the key of B minor. This is another unusual destination given the song’s tonic of E Major, but it is the parallel minor of the song’s dominant. Although the song does not feature any modal borrowing, this transition can be understood as embellishing the minor “v” of E major, which is a relatively common technique for the genre (as was seen with “Scarecrow” and “Saturday”). The bridge only comprises 15 seconds of the song’s duration, so it is fascinating that such a starkly contrasting idea stands in such isolation.


The Kinks, “Days”


Music during the Romantic era began to explore modulations beyond closely related keys (those either a fourth or fifth away from tonic, plus their relative minor keys), and one of the more common ways in which composers achieved this was through the use of chromatic mediants. A chromatic mediant from any given tonic can be found either a major or minor third above or below it, and the tonic triads should share one common tone. This type of modulation is rare in rock/pop music, but two good examples can be found with The Kinks’ “Days” and They Might Be Giants’ “Birdhouse in Your Soul”. Here are the progressions and formal diagram for the former:


Chorus 1 (D Major):

D (I)   | A7 (V7) | D (I) / G (IV) / D (I) / A7 (V7) | D (I)   |

D (I)   | A7 (V7) | D (I) / G (IV) / D (I) / A7 (V7) |

D (I) / G (IV) | D (I) / G (IV) | D (I) / G (IV) / D (I) / A7 (V7) |

D (I) / G (IV) | D (I) / G (IV) | D (I) / G (IV) / D (I) / A7 (V7) | D (I)   |


Verse 1 (F Major):

Bb (IV) / F (I) | C (V)   | Bb (IV) / F (I) | C (V) / Bb (IV) |

F (I) / Bb (IV) | F (I) / Bb (IV) / F (I) / C (V) | F (I) / Bb (IV) |

F (I) / Bb (IV) | F (I) / Bb (IV) / F (I) / C (V) | F (I)   |

A (V/vi)   | Dm (vi)   | A (V/vi)   | (2/4): Dm (vi) / C (V) |

(4/4) Bb (IV)   | A (V/vi, V back to D Major) |


Chorus 2 (D Major):

D (I)   | A7 (V7) | D (I) / G (IV) / D (I) / A7 (V7) | D (I)   |

D (I)   | A7 (V7) | D (I) / G (IV) / D (I) / A7 (V7) | D (I)   |


Verse 2 (F Major):

Bb (IV) / F (I) | C (V)   | Bb (IV) / F (I) | C (V) / Bb (IV) |

F (I) / Bb (IV) | F (I) / Bb (IV) / F (I) / C (V) | F (I) / Bb (IV) |

F (I) / Bb (IV) | F (I) / Bb (IV) / F (I) / C (V) | F (I)   |

A (V/vi, V back to D Major) | A   |



D / Eb | E / F | F# / G | G# / A | D   |



Intro: 0:00 (D only)

Ch1: 0:07

V: 0:40

Ch2: 1:17

V: 1:36

Ch1: 2:05

Coda: 2:38


The two keys used here are D and F major, which are chromatic mediants of one another. F is a minor third from D, and the two tonic triads share exactly one common tone (A). The sounds of these modulations have been established by classical music, but they also work here because of the transitions between the two keys.


The verse moves smoothly back to the chorus through the use of a pivot chord. The A Major that concludes this section is both a secondary dominant in the verse as well as the diatonic dominant in the chorus. Its function as a secondary dominant is firmly established at this point because this is the third time this chord appears, at least in the first verse. This section ends by briefly tonicizing D minor (D Major’s parallel minor), so the impetus for the return back to D Major has a strong foundation.


The shift from chorus to verse is not as theoretically sound because it lacks a pivot chord, but it works just as well in practice because of the use of the plagal progression. I, IV, and V chords are all used liberally in both sections, but the verse beginning with a plagal progression helps to manufacture a sense of seamlessness that might not be there otherwise. This progression is repeated numerous times to end the chorus, so it also forms a concrete connection across the two sections.


Another notable aspect is the song’s form. The two sections of this song (chorus and verse, but their labels could be flipped) appear in two different forms. When each section returns, it is abbreviated from its original statement. Both sections remove the latter parts of their original forms to create truncated versions of themselves. This is surprising not only because pop music usually repeats material the same each time, but also because when sections are modified, they are often expanded rather than contracted.


They Might Be Giants, “Birdhouse in Your Soul”


“Birdhouse” – which I hear also works well for jazz big band – also features this sort of tonal movement, and chromatic mediants can be found in two of its sections. The first (and main) example actually demonstrates modal borrowing and/or a tonicization rather than a complete modulation, but the second example commits entirely to the modulation.



C (I)   | Eb (bIII)   | Bb (bVII)   | Db (N) / G7 (V7)



C (I) / F (IV) | C (I) / F (IV / G (V) | C (I) / G (V) / F (IV) |

Eb (bIII) / Ab (IV/bIII) | Eb (bIII) / Ab (IV/bIII) |

Eb (bIII) / Cm (vi/bIII) / Ab (IV/bIII) / G (V)



C (I) / F (IV) | C (I) / F (IV) |



C (I) / F (IV) | C (I) / F (IV) | C (I) / G (V) / C7 (V/IV) | F (IV) / G (V) |

C (I) / F (IV) | C (I) / F (IV) | C (I) / G (V) / C7 (V/IV) | F (IV) / G (V) |

Am (vi) / F (IV) | D (V/V) / F (IV) | (2/4) G (V) |



Am (vi) / F (IV) | D (V/V) / F (IV) | Am (vi) / F (IV) | D (V/V) / F (IV) |

(A Maj): F#m (vi) / D (IV) | B (V/V) / D (IV) | E (V)   | E   |

A (I)   | C (bIII)   | G (bVII)   | Bb (N) / G (V back to C Major) |


(As discussed in Part I, “N” represents a Neapolitan chord, which is a major triad built on the lowered second scale degree.)



Intro: 0:00

Ch: 0:15

Tag: 0:29

V1: 0:34

Ch: 0:59

Tag: 1:13

Bridge: 1:18

V2: 1:47

Ch: 2:12 (4x’s)


The chorus briefly tonicizes Eb Major, but its brevity, containment within the chorus, and consistent use of modal borrowing leads me away from calling it a modulation. This tonicization is once again smoothed out by the reliance of plagal progressions in not only both key areas of the chorus but also the tag and verse sections. The Ab Major chords could also be labeled as bVI chords via modal borrowing, but I opted for the secondary plagal notation I have used throughout this series to highlight the parallel function here to the first three measures of the chorus.


The idea of harmonic sequence also appears in the bridge. It restates the last phrase from the song’s verse, but then it modulates the same progression to the key of A Major (also a chromatic mediant, but moving down a minor third instead of up). Although this progression is not much longer than what appears in the chorus and is also self-contained within the bridge, it makes more sense as a modulation largely because these chords cannot be explained through modal borrowing. The progression here also establishes its new tonic more firmly – when it finally arrives at A Major, the chord lasts a full measure, and it is preceded by two full measures of its dominant. The progression in the chorus uses its implied tonic of Eb Major more fleetingly, and it is never preceded by its dominant.


The transition back to C Major from the end of the bridge is pretty interesting, as well. It achieves this using another harmonic sequence by restating the intro progression (I-bIII-bVII-N-V) in the key of A, except is retains the intro’s final chord of G Major as a pivot back to C. The specific chords used in this new context are noteworthy because C, G, and Bb Major are all used in both the intro and bridge versions of this progression, but except for the final G, they all have different functions.


All of these songs feature some degree of tonal ambiguity. The other common thread seems to be that their collective sense of harmonic and tonal adventure is facilitated by the comforting use of plagal progressions. Because of the familiarity of this progression’s sound, songwriters have used it as a springboard for exploring unexpected areas and, as a result, achieving something that is deceptively unique.



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