Question regarding "Dark Necessities" by Red Hot Chili Peppers

Question

The song is written in C-minor. This, to me, means that most of the music will be playable on a E-flat major scale. I understand that not all chords will necesarily be found in this scale (borrowed chords and all), and I understand that with a key change, the scale also changes.

But why would an entire scale change over a simple chord progression without a key change?

At the 2:57 time mark, there is a musical bridge. During the bridge, the bass-line is simple descending scales (BEAUTIFUL). There are 4 descending scale runs before they repeat all in the key of C-minor:

The first descending scale is over an E flat major chord, and it is a E flat major scale (in Ionian mode - as would be expected from the Key of C minor) But here things get weird The second chord is D flat major (a borrowed chord). The descending scale played is a A flat Major scale in Lydian mode (as if the key is now A flat major?). The third chord is F minor, and the scale played is, again a A flat Major scale (played in Aeolian mode - also as if the key is A flat major) The last chord is A flat major, and the descending scale played is a A flat Major scale in Ionian mode - also fitting in with a key of A flat major.

Wait... Please don't tell me I wrote all that just to figure out they modulated from Cminor to Aflat Major using E flat major as a pivot chord?

Nice first question, Antonie...

Answer 1

They didn’t modulate. It’s a different kind of music theory that some call “modal improvisation”. It’s very common in jazz solos.

For each chord in a progression, the soloist re-evaluates the scale they are using as the basis for their solo. The main reason to do this is because chord progressions in jazz, and sometimes in pop and rock, are not necessarily diatonic.

Choosing the scale for each chord can be a bit complicated. It depends on the chord, the preceding and following chords, and the melody (implied or explicit). Even though the scales change frequently it is not considered a modulation. One of my teachers said they think of it as “the key of the moment”.

Answer 2

Like so many, you seem to have fallen into believing that diatonics are the only ones that work in a specific key - other notes don't belong. That's just not the case. It may well be a good initation into music, just like kids are told you can't take 6 from 3, which they later find out just isn't the case, but it keeps things 'safe'.

It's probably true that a lot of music is diatonic, but some isn't, therefore there's no rule saying it should be. The modal mix, borrowing, etc., are jusst ideas humans have come up with to explain what could be happening in certain circumstances - which happen quite a lot !

There's nothing to stop a composer writing whatever he wants. Some of it won't sound good, but it won't necessarily sound bad when it goes off-key diatonically, particularly in minor keys, where there's a bigger choice of notes than major. When there's a 'foreign' chord, the melody will usually follow the notes from that chord (which usually happens in most pieces anyhow), so it's not surprising you find this in 'Dark Necessities', and thousands of other songs.