On minute 18:00 in the “Harmony Part 1-5: Harmonic Functions and Progressions” video, regarding Substitute Chords, the progression in the middle is:
IV – (ii) – V. (The real chords are F – Dm – G)
Why is this considered a prolongation chord progression? Which chord is being prolonged? How can V be related to IV or ii?
It can really be considered both. Think of this as two ways to imagine a progression.
In way of thinking, the progression is just IV – V, and then later on, you realize you can add in ii as a passing chord because it is a valid substitution. You could also just completely replace the IV.
In the other way of thinking, you write a diatonic progression that proceeds from IV to ii to V.
With music, just like in math, there are different ways of thinking about the same problem.
Thanks for the question.
That would be correct.
So in fact, using the first way of thinking that you stated, the chord being prolonged is IV, isn’t it? We prolong the IV chord by adding the ii chord, and the V chord is in reality a new chord in the progression that has nothing to do with the previous prolongation.
Am I right, or did I miss something?
Thanks for your answer.