The minor key universe
How do we bring Dorian and Phrygian into the fold?
In a previous post, I suggested that we think of an expanded major key universe that includes the major scale, Mixolydian mode, Lydian mode, and maybe also Mixolydian b6. In this post, I present a similar approach to minor keys, by extending the logic of Western European tonal theory to cover some additional minor scale variants.
Music theory learners may wonder why there so many minor scales in European classical tradition. There really aren't, it's just one minor scale, but it has flexible sixth and seventh degrees. Here's the C minor scale, whose sixth and seventh degrees are A-flat and B-flat by default.
You can raise the B-flat to B to make G7, the V7 chord in C minor. The version of the minor scale with a raised seventh is called harmonic minor.
Harmonic minor includes an augmented second between the flat sixth and natural seventh. Europeans did not historically like that big jump, so to smooth it out, they sometimes raised A-flat to A-natural. The version of the scale with both the raised sixth and seventh is called melodic minor.
You may have heard something about how there are different versions of melodic minor depending on whether you are ascending or descending. For the sake of your mental well-being, you should ignore that.
So here are the European classical minor scales side by side.
The crucial thing to remember here is that these are not really three different scales, they are one scale with flexible sixth and seventh degrees. Once you have internalized that, let's move on to how pop music approaches minor.
Sometimes minor key pop songs follow the conventions of the European canon, with "proper" harmonic and melodic minor. More often, however, they don't. It's very common for pop songs to stick entirely to natural minor, and to not raise the sixth or seventh scale degrees at all. The technical term for this all-natural-minor sound is Aeolian mode. Examples of tunes in Aeolian include "In the Air Tonight" by Phil Collins, "Careless Whisper" by Wham, “Family Affair” by Mary J Blige and “Espresso" by Sabrina Carpenter.
Pop also uses a version of the minor scale that just about never appears in the European canon. If you raise the sixth degree but keep the seventh flatted, you get Dorian mode.
Dorian was ubiquitous in medieval Europe, but it fell out of favor in the Baroque era. It persisted in European folk music, though, and it had a big revival in the twentieth century, maybe because it happens to overlap with the characteristic pitches of the blues. Examples include "Scarborough Fair" as recorded by Simon and Garfunkel, "Spiritual" by John Coltrane, "Oye Como Va" by Tito Puente, "I Wish" by Stevie Wonder, and many James Brown classics.
In addition to the flexible sixth and seventh degrees, you could also think of the second degree of the minor as flexible. If you lower the second degree of C natural minor from D to D-flat, you get C Phrygian mode.
Phrygian mode used to only appear in pop when people wanted to imitate Iberian music. However, metal musicians love Phrygian, and it has also become a go-to sound for rap producers. Examples include "Doo Wop (That Thing)" by Lauryn Hill, "Get Ur Freak On" by Missy Elliott, and "Versace" by Migos.
There is one more scale from the minor key world we could discuss, and that is the so-called blues scale.
There are two questions about this scale: is it actually minor, and is it actually a scale? It has that minor third above the root, and it certainly sounds good in minor keys. But in the blues, you more customarily use that minor third over dominant seventh chords. The major/minor distinction doesn't really apply to the blues, which is a tonality unto itself.
The real question about the blues scale is not its major-ness or minor-ness; it's the question of whether it is a scale at all in the European sense. It would be more accurate to think of it as a characteristic set of pitches used in blues melodies, and hardly a complete set. It would be even more accurate to think of the blues scale pitches as equal-tempered approximations of the flexible pitch zones that you actually use to play blues melodies. Playing the blues scale can sound believably "bluesy" if you do the phrasing right, but in no way should you think of the scale as the basis of actual blues music. I include it here just to let you know that using it can give a bluesy inflection to minor key music.
So here's how I think we should approach the expanded minor key universe of Anglo-American popular music: a minor scale with flexible second, sixth and seventh degrees, and that can also have a flexible fourth/fifth if you want to add blues into the mix.
Here's a flowchart representation of the information above.
Why talk about flexible pitches rather than just adding Dorian and Phrygian to the existing explanation of minor? I have a couple of reasons. First, while there are some purely modal minor-key pop songs, it's more common for them to mix modes together, or to combine modal minor with classical minor. I want to be able to distinguish a purely Dorian tune like "Soul Power" by James Brown with a blended minor tune like one of these:
"Eleanor Rigby" by the Beatles combines E natural minor and E Dorian.
"The Thrill is Gone" by BB King uses B Dorian for the Bm7 chord, B Aeolian for the Em7 and Gmaj7 chords, and B harmonic minor for the F#7 chord (though BB just plays blues in B on top of all of that.)
"Forget Me Nots" by Patrice Rushen combines F# natural minor and F# Dorian.
The main groove in "Let's Dance" by David Bowie combines Bb Dorian and Bb natural minor.
"Slippery People" by Talking Heads combines A natural minor and A Dorian.
“Kick Push” by Lupe Fiasco also combines A natural minor and A Dorian.
For all of these tunes, I would rather just say that they are minor, and that the sixth is sometimes flat and sometimes not (or whatever the case may be) rather than invoke the diatonic modes. That is closer to how I conceive of these tunes anyway. If I play "Slippery People", I am not thinking about Aeolian and Dorian, I'm thinking, "flat sixth here, natural sixth here."
So how should we teach minor keys? I think we should say something like this: "Minor keys always involve a minor third, by definition, and a perfect fourth and fifth. The seventh is usually flat, except in special situations like V7 chords. The second is usually natural, except in special situations when you want that Phrygian sound. The big question is the sixth. If it's flat, it's probably a natural minor situation. If it's natural, it's probably Dorian." This might seem complicated, but if it aligns with students' listening lives, then they should have no trouble assimilating the information.