What is a chord progression?

Let’s look back at the G diatonic collection of triads we had in the last module. As you will see, I’ve applied numbers to each of the chords in the scale, starting with 1 on the tonic and moving up from there. We can assign each of these chords, or numbers, a harmonic function. A harmonic function is the collective tendency of all of the notes of a chord and where they want to ‘move to.’ These harmonic functions are completely subjective and specific functions are often tied to specific styles. For example, a 1700 composition by Bach will have completely different harmonic functions than pop music made in the 2000s. This extends to geography and culture as well - a modern Latin pop artist may use different functions of harmony than an artist from the United States. That being said, we can still boil down harmonic tendencies into three main functions regardless of how they’re used: tonic, dominant, and predominant.

Tonic chords are defined by their ability to ground the music and establish its tonality. As you could guess, the 1 chord which is built on the tonic of the scale fits this definition perfectly. However, the 3 and 6 also often serve tonic functions when modulating to different tonal areas. Remember in the last module we talked about temporarily moving to the major mode in Keep an Eye on Dan’s chorus? That’s all that modulation is - however using these as a tonic function would imply that the mode would switch to either B minor or E minor if we are starting in G major. In addition to functioning as tonic chords, 3 and 6 can sometimes be substituted as predominant chords as well.

Dominant chords are defined by their relationship to the tonic, having a strong tendency to want to move to the 1 chord of the scale. The 5 and 7 chords are considered to be dominant in function due to several technical and historical reasons. An easy observation to make that supports the dominant function in the G major collection is the note F#, contained in both the 5th and 7th chords each. This note serves as a leading note that is very close to the tonic note G. This adds to the ‘collective tendency’ of these chords leading to the tonic.

Predominant chords are defined by their relationship to - you guessed it - the dominant function. The last two chords to be described, the 2nd and 4th, are considered predominant in function. They historically each have a collective tendency to lead to either of the dominant function chords. However, the 4th chord alone often ignores this function in modern pop music and is substituted as a dominant chord. This weak, pseudo-dominant function allows for cyclical chord progressions that seem like they could go on forever. When the 4th chord is used in this way, an even weaker chord is substituted into the predominant function, such as the 6 or 3 chord.

By using numbers, we can identify these harmonic functions in other diatonic collections that aren’t G. For example, the fifth chord in the A diatonic collection, E major, will still have a dominant function despite it not being the same as the fifth chord in the G diatonic collection, which is D major. This is important to keep in mind, as several songs can be in several different keys, yet still have the same chord progression.

Furthermore, these same functions are mostly consistent with minor pitch collections as well, specifically harmonic minor pitch collections where the altered pitch reinforces the same functions found in major scales.

1 - 5 - 6 - 4

We won’t stay long here, as the Axis of Awesome video gives you plenty of examples to hear. What we can do, however, is look at the progression and see how it functions in a specific song. Below is a simplified piano part found in the first part of the verse of Let it Be by The Beatles. Listen and follow along - remember that each sound you hear on the piano is the notated chord. We are in the key of C major, so the C major chord is our 1 chord.

Note that you will find a new chord symbol in the last measure. It can be read as “F over A” and it is an F major chord but with the ‘A’ pitch as the lowest note instead of the usual ‘F.’ This is called an inversion when compared to the triads we’re used to seeing, and using them can help us create really smooth chord progressions - as you will soon identify.

In the song, the 1 chord is used to establish the tonality of the piece. Most chord progressions will start here because, well, that’s just how we have been doing music forever. However, starting with the tonic allows us a great deal of freedom in where to go next since its functional relationship is only defined by tonality and not other chords. By moving to the 5 chord first, we set up a really nice transition to the following 6 chord, which rises all of the notes by one step. Finally, you can hear why the movement from the 6 chord to the 4 chord is so smooth - they share two out of the three notes (minding the repeated A’s) between them. Since the 4 chord is being used as the dominant function to return us to 1, we can technically define the 6 chord’s function as predominant.

And that’s it! While there is no objective reason to explain why this chord progression works so well, you should now be able to understand how these chords have tendencies that make them want to lead to other chords. When these tendencies are followed, they tend to create some pleasing results. Additionally, by distilling these chords down to core tendencies, we can explore different progressions using the same justifications used above.

Substituting chords

To reiterate, the function of a chord is what we’re really analyzing in these pieces, not the actual chord itself. It doesn’t matter where the 4 or 5 chord is in the chord progression, but rather how they function. As mentioned earlier, the 4 chord in this progression is used as a weak dominant function that brings us back to 1. Just like the 4 chord can be substituted for a dominant function, so can the other chords and their functions.

In the “1 - 5 - 6 - 4” progression, the 6 chord serves as a nice predominant function to the 4 chord. One of the reasons this works so well is because the 4th and 6th chords of the pitch collection actually share 2 of the 3 notes. Meanwhile, the 5 chord doesn’t really serve a function other than moving us to the predominant 6th chord. This works well since the two chords are only a step away from each other. By knowing these tendencies, we can create new chord progressions that have virtually identical tendencies.

Let’s listen and analyze the chorus of Easy On Me by Adele. When analyzed in the key of C major, the chord progression created is “1 - 5 - 2 - 4,” with the 4 chord again being used as a dominant function to cycle us back to the 1 chord. When compared to the last progression we clearly see one different chord, but the progression seems to still function in the same way - meaning that it is nearly indistinguishable from it.

Additionally, there are a couple of new things to keep in mind as you look and listen. Note that at the end of each measure there is an additional chord colored red. These are used to aid in the transition of the chords but are not directly functional in the grand scheme of things. You can think of it as adding some flavor and color to the song. Also, you will see a new chord symbol in the 3rd measure, Gm7. This is called a seventh chord, and just know that for know it means we add a new note to the triads we have been working with - some more flavor, color, and additional functionality. Lastly, I’ve added another staff to the examples. These pairs of staves (this is the plural word for music staff) are what piano players typically see with each staff corresponding to each hand. The new, lower staff is for the left hand and adds some of those nice bass notes/lines that you have certainly heard in music before. Go all of that? Okay, let’s get into it.

Functionally, the 1 chord moves to the 5 chord through both a shared note and stepwise motion. At the end of this measure, the bassline moves and recontextualizes the chord, while also moving stepwise to the 5 chord. We then get to the 2 chord by its shared note and stepwise motion of the other three notes. This transition is also assisted by the passing chord that happens on the fourth beat of the measure which creates additional stepwise motion in the other direction. Then, the 2 chord moves up to the 4 chord by another transitionary chord and the three notes they share with each other. If you look at the pitches of the Gm7 chord, you will see that the B♭ triad is actually present in the chord. The movement in the baseline completely recontextualized the chord as we enter the 4th measure. While not pictured, the 4 chord will eventually loop back to the 1 chord using its shared pitch, ‘F.’

Despite having two unique chord progressions, we could make an argument that they function very similarly - both in sound and technique! This freedom to add and substitute chords is important to understand as we continue to listen and analyze music. As you are about to see, these substitutions and variations on chords and functions are what allow so much freedom in writing music.

1 - 4 - 5

This chord progression is the simplest version of the most common functions in chord progressions. It consists of a tonic, predominant, and dominant in that order. While most chord progressions are longer than just these three chords, you can simplify the overarching progression to these three key functions - no matter how many chords you add or substitute in. Let’s check it out with Silk Sonic’s Leave the Door Open.

Now, this may seem like a lot to take in - but don’t freak out and just focus on the chords I’ve highlighted in red. The first two chords are iterations of the tonic chord, establishing our tonality of F major…or a mode that is close to it. We have a couple more chords in the last two measures, but eventually, we get this really fast hook at the end that completes the predominant-dominant function we’re looking for. It took some time, but we eventually got there!

We could try to explain the entire function of the other two chords, but this chord progression in its entirety is by no means common and features many chords that are borrowed from other pitch collections. Seems like a fine job for some incredibly enthusiastic Bruno Mars theorist, but far beyond our scope. It’s far more pertinent that we are able to identify the simplified function of “1 - 4 - 5.” Though, if I were to give you an idea of what the 7 and 3 chords are doing here, I’d guess they’re being used to cycle through chords from different pitch collections, creating a miniature dominant to tonic function within itself. If you were to pretend that the piece is in A minor, E minor going to A minor is 5 to 1. If you decide to continue listening to this piece, you will find a whole lot of slick key changes and other neat harmonic moments. For now, however, let’s check out one last chord progression before wrapping up.

1 - 2 - 3 - 2 - 1

Another unique progression that is hard to miss made it into one of 2021’s top songs. This progression is heavily reminiscent of the pitch collections and progressions found in Spanish flamenco music. Each chord is created from the notes of the phrygian (pronounced FRIJ - ee - uhn) mode which creates a series of three major chords in a row. Just like major and minor are pitch collections based on specific patterns of whole steps and half steps, so too is the phrygian mode! You can see the collection to the right here, but don’t get too caught up in the theory. We’ll just be taking a look at its function, or lack thereof, with our next song by Lil Nas X.

I alluded to a lack of traditional function when I first introduced this progression, and for good reason. Taking what you have learned in this module so far, what chords could serve as the tonic, predominant, and dominant? You may be inclined to just label them consecutively, after all, there are only three chords in the entire section. Though, I would argue that there is not a strong case for hearing or analyzing the functions we’ve since learned about.

What we have here is a completely new set of functional rules, derived from a tradition of music that is not based out of Northern Europe. This is the exact same case with the previous functions, mind you, just from a different tradition. Within this realization is the understanding that the arbitrary rules derived from western chord functions will not necessarily work when applied here and vice versa.

What we can recognize, though, are individual pitch tendencies. This is a great example to do so since the progression is essentially defined by the closeness of each chord to one another. That is to say, as we’re changing chords, we only move one step at a time. The instrumentation of the guitar is another clue as well. With a slightly altered tuning, each of these chords are easy to produce and play on the guitar. Finally, we can consider the tradition of Spanish flamenco music contributes considerably to how this progression works. If we were to study more works in that genre, the more patterns we would be able to collect and analyze that support the common use of this progression.

At the end of the day, there are millions of unique chord progressions we could analyze to death. It’s not so important that we can precisely analyze each unique progression, but instead be able to recognize common patterns and anticipate functions in the music we listen to. And now that you’re finished with this module, you are well on your way to being able to identify these commonalities in your everyday listening.