The functional notation for chord progressions is an extension of the traditional notation which is fully compatible with it (you won’t have to learn any new symbols if all you want to do is to play a given chord progression on an instrument). It is a notation I have developed in order to speed up the process of learning to understand music and to improvise.
In order to understand the notation, it is first necessary to turn our attention to the structure of the diatonic scale (i.e. the major or the natural minor scale). Let me use the C major/A minor scale as an example. Most people think about A B C D E F G as about the order of the tones of the scale, and indeed, this is the order we usually use when thinking about melodies.
However, there is another, perhaps even more important order of the scale. All the tones of the scale can be ordered so that each step represents a perfect fifth. In the case of C major/A minor, this order is:
This gives us a certain insight into the structure of the scale. The scale can be decomposed into two important building blocks: the major block, F – C – G, and the minor block, D – A – E. As you can see, the tonic (the tonal centre) of the major scale is in the middle of the major block, the tonic of the minor scale is in the middle of the minor block.
Remember that the dashes represent the perfect fifth, therefore F – C – G is a diagram showing us the subdominant (F) and the dominant (G) of the C major scale. Similarly, from D – A – E, we see that the subdominant of A is D and the dominant is E.
The chord progression C → F → G7 → C feels about the same as Am → Dm → E7 → Am, only the overall mood is different. That’s not very surprising, even from the viewpoint of the traditional music theory: the first progression was I – IV – V7 – I in C major, the other one was i – iv – V7 – i in A minor.
The unified notation
What the traditional theory fails to see is that these two blocks feel about the same even if they build a larger scale together. There is no need to write “III” instead of “I” for C when we are in A minor and “vi” instead of “i” for Am if we are in C major. Instead, we shall write (using C major/A minor as an example):
This has a very important consequence: if you remember all the triples X – Y – Z whose members are the perfect fifth apart (and there are basically only 7 of these), you will need to remember only the maj and the min degree of each scale to reconstruct it. For example, if you remember sub and dom of the A minor scale (i.e. D and E), you get sub and dom in A major for free, since they are the same. The dim (diminished) scale is also easy to remember, because it is just the next letter after min in the alphabetical order (perhaps with an accidental).
This allows us to write chord progressions in a “major/minor”-independent way. For example, I – vi – ii – V – I would be written as
And, in the minor scale, i – iiø7 – V7 – i would be written as
The last example demands explanation. What is Dom7? As you probably know, there are three different minor scales. By capitalizing the first letter, we make it clear that the scale we are in is the melodic minor scale. Why not harmonic? Because this way it is more natural for progressions like min – Sub – Dom – min.
Combined notation with chord symbols
I stated at the beginning that the functional notation would be compatible with the standard notation for chord progressions, which doesn’t seem to be the case so far. Chord progressions are traditionally denoted using chord symbols, e.g. C – Am – Dm – G7 – C. Since we already know the names of the degrees and we don’t have to care about the major/minor dichotomy anymore, we can simply write the scale degrees as additional information to a traditionally denoted chord progression:
I don’t use the dashes here because I find them distracting. I also don’t add the “7” to “dom”, because we can see it is a “7” from the chord symbol itself. Of course, this style of writing is impractical when we need to write a progression in a block of text. Then the function will be denoted using a superscript: majC minAm subDm domG7 majC.
Now, imagine that every chord progression in a songbook were written this way. Wouldn’t it be of immense help to people trying to understand music theory and to improvise? I’ve had good results with this approach myself; being able to see the function in a scale every time you see a chord in a progression does a great job in helping one to memorize the scale degrees of all commonly used scales, and that’s why I’ve already started compiling songs and compositions for a songbook—hopefully, it will be ready some time in 2015.
Also, this article doesn’t explain everything—how to go about modulations, augmented sixth chords aka tritone substitutions, etc.? This is a topic that will be treated in a separate article (which hasn’t been written yet).