A few years ago, the comedy-rock band Axis of Awesome pointed out a great truth — that every pop song ever written uses the same four chords in the same order.
The fact that it’s not really true makes it no less impressive. I mean, every single song!
Enjoy a couple minutes of this, then we’ll talk.
So why are songwriters addicted to I-V-vi-IV? Because for a basic progression, it’s actually pretty effective. Not a thing of genius, just a really solid workhorse. It’s been robbed of its sparkle by overuse, but it’s worth taking apart to see why it has become such a go-to.
As I said in The Hidden Grammar of Music, the most common place for any chord to go is up or down a fifth, and the tonic chord is no exception. In this progression, the I chord goes to the chord it is most closely related to, the dominant, the neon arrow: V.
Only one chord to go. But which one? We could repeat I, V, or vi, but that’d be boring. We want something new to round out the phrase. There are four other chords in the key. Which would be the most satisfying?
As a bonus, when you repeat the progression, IV goes back home to I in a very satisfying and common progression called the plagal or “Amen” cadence.
None of this makes the I-V-vi-IV progression inevitable, but it does make it sensible as a recurring thing, like subject-verb-adjective-object in written language.
Nutshell: If you start in the most common starting place, make the most common harmonic move, follow it with something just a little different, then fill in the one remaining gap in the scale, you get the most common pop progression on Earth.