The Great I, IV, V Mystery

What’s the deal with numbers and music? For many of you, I’m sure the association is a mystery. You’ve probably heard another musician (maybe you’re that musician) sound off something about using a I, IV, V progression.

 

 

 

 

What’s the deal with numbers and music? For many of you, I’m sure the association is a mystery. You’ve probably heard another musician (maybe you’re that musician) sound off something about using a I, IV, V progression. Maybe you were playing with some folks and one of them corrected you saying, “No dunderhead, you’re supposed to change on the V chord, not the IV.” Whatever the context, if you were puzzled by the combination of numbers and music, allow me to enlighten your understanding just a bit.

What does it mean when a musician says, “Play the I, IV, V in E”? Basically, all music theory is based on the major scale. That scale can be played in any key. In our example, the key I happen to be using is E. Think of that key as a starting point for your scale. (In musicgeek speak it’s known as the tonic note.)

Next, the major scale is composed of eight notes formally, but for our purposes, we’re only going to list seven since the eighth note is just the octave or double of the first note. For the key of E, it goes like this:

E     F#   G#    A    B    C#    D#

 

Next, we assign each note a Roman numeral value, like this:

E    F#    G#    A    B    C#    D#

i      ii       iii     iv    v     vi      vii

 

We call these numeric values scale degrees. As you can see each note in the key of E major now as a scale degree associated with it. What you may not know is that each note also has a chordal counterpart. For example, the counterpart of E will be E major. The counterpart of F# will F sharp major and so on. So when your jammin’ buddy says “We’re doing a I, IV, V combination in E,” he’s telling you that you’ll be playing a chordal arrangement in the key of E, where E = the one; A = the four; and B = the five. This system works for any chordal combination based on this convention. You could just as easily relate a different set of chords by simply choosing the Roman numerals associated with them. For example, if I told you to play a I, II, III, combination, I would be communicating that the progression is to be played using E, F#, G# . This formula for relating chord combinations, though unconventional, is a kind of shorthand, which will allow you to relate music information in a much more efficient manner.

If you have questions or corrections, please post them on this thread or email me using the “Make Contact” page and I’ll make updates to the post where applicable. Viewer mail will be answered in separate posts.