Functional harmony
Why the same four chords come round in hundreds of songs, how to give every chord a number, and why that is what lets you learn a song by ear.
Did you think every hit is a fresh invention? Most of the pop, rock and blues songs you love use exactly the same progressions. That is not laziness — it is what happens when something works.
In this lesson we will understand why it works, and how it turns you into somebody who can guess the next chord in a song they are hearing for the first time.
Two things from the two lessons before it, and both of them are short.
From the lesson on the scale: that a scale is seven notes at uneven distances, and that you can number them from one to seven.
From the lesson on building chords: that a chord is built by skipping — take a note, skip its neighbor, take the next one, and do that three times.
That is all of it. Now we join the two together, and the rest of theory falls out of the join.
In the previous lesson we built a triad on C. Now we do it on every one of the seven notes of the scale — the same rule exactly, skip a neighbor — and here is what comes out in C major. The third column is the shorthand English-speaking musicians use for the result: a Roman numeral, written in capitals when the chord is major and in lower case when it is minor, so that the degree and its quality arrive in a single symbol.
| Degree | The chord | Roman numeral |
|---|---|---|
| 1 | C major | I |
| 2 | D minor | ii |
| 3 | E minor | iii |
| 4 | F major | IV |
| 5 | G major | V |
| 6 | A minor | vi |
| 7 | B diminished | vii dim |
We chose nothing here. We used only the seven notes of the scale, and even so some of the chords came out major and some came out minor. The order of the steps inside the scale is what settled that — and it is the entire reason the same three major chords always land in the same places, in every key in the world.
The seven chords do not carry equal weight. They divide into three jobs:
Home is the chord on the first degree. It is the resting point, and songs usually start and finish on it. When you arrive there, the ear feels that you have arrived.
The road is mostly the chord on the fourth degree. It carries you away from home without making any drama out of it — opening, widening, pleasant.
Tension is the chord on the fifth degree. It is the one that creates the pull back home, and that pull is not a matter of taste: sitting inside it is the leading tone we met in the scale lesson, the one a mere half step below home. A half step is a small distance, and the ear wants to close it.
The moment you can hear those three jobs, you stop hearing a list of chords and start hearing a story: we set out, we went further away, tension gathered, we came home.
This is the oldest and most common progression there is, and it is precisely the three jobs one after another. In G major it sounds like this:
Play four beats on each chord: G, C, D, and back to G. Do that four times through and you will hear that you are already inside a song — nearly all of the blues is built from these three, and so is half of rock and roll.
One piece of attention here is worth gold: listen to the moment D turns back into G. That feeling, of a door swinging shut, is exactly what we call the resolution. It is the thing your ear has been waiting for all song long without your knowing it.
Now we swap a single chord and get the most common progression in pop of the last forty years: one, five, six minor, four.
Play it as a loop, a bar to each chord. You already know this one — not from this lesson, from your life. Dozens of hits use exactly that sequence, and not for want of imagination: it holds both the tension and the way out of it, and the minor chord in the middle adds just enough shade to stop the whole thing turning sugary.
Practise it against a real pulse, or it stays an exercise:
Metronome at 70 — one bar per chord, four beats
And when it sits comfortably, change the order without changing the chords. Start from the minor instead. Suddenly those same four sound like an outright sad song. Nothing changed but which one was put first.
With the seven chords of the scale and the three jobs, you can assemble endless sequences. In practice, a handful of them come round again and again:
| The progression | In G major | How it feels |
|---|---|---|
| I, IV, V | G, C, D | Direct and strong. Blues, rock and roll, folk |
| I, V, vi, IV | G, D, E minor, C | Classic pop. Lifting, and it closes nicely |
| vi, IV, I, V | E minor, C, G, D | The same chords, a minor opening. Instantly more dramatic |
| I, vi, IV, V | G, E minor, C, D | Nostalgic. A great many older ballads |
Notice that the third row and the second one hold exactly the same four chords. The only difference is where you begin, and that is enough to change the whole character. There are not many places in theory where you see so much in return for so little.
So far we have been talking in major. In minor the same idea works, except that home is a minor chord — and the two degrees around it come out major, which is what gives you the dramatic sound people associate with rock and metal.
The most common progression over there is home, and then the two degrees below it. In A minor that comes out as A minor, F, G — and if you have ever played something that sounded epic, that is most likely exactly what you played.
And it is worth knowing that songs cross between these two worlds all the time: a minor verse opening out into a major chorus is one of the oldest tricks in the book, and it works almost every time.
The practical rule: if a song refuses to settle around a major chord, try counting from the minor. Very often you will find that you were in the right key and started from the wrong place.
Now the part that turns all of this into a working tool.
When you think in numbers rather than names, you can move a song into any key at all. “One, five, six, four” in G is G, D, E minor, C, and in C it is C, G, A minor, F. The same song, the same feeling, the same numbers.
Three very practical abilities come out of that:
And yes, it looks like a conjuring trick the first time somebody does it in front of you — but it is not an inborn gift, it is recognizing a handful of patterns that keep coming back.
It really is worth a try: take a simple song you love, find the first chord, and work out the rest by job rather than by name.
This is the exercise that turns the whole lesson from information into a skill, and it takes five minutes a song.
That last step is the real test, and it is also what turns one song you have learned into a song you can play anywhere.
| What happens | Why | What to do |
|---|---|---|
| Every chord sounds the same | You are playing them with no context around them | Always play a sequence, and come back to the first chord at the end |
| “I cannot hear the tension” | There is nothing to compare it against | Play the five and then stop. You will feel something missing |
| The song will not fit any progression | It may well be in a minor key | Try counting with the minor chord as home |
| Hard to find the first chord | You are hunting for it one sound at a time | The last chord of the song is almost always home |
| You know the theory and do not play | You studied it and never practiced it | Always with a metronome, always as a sequence |
That is the set — you have a scale, chords and families. From here the natural next step is getting to know the whole neck, so that you can play these progressions anywhere and not only down in the open position.