33. Two-Five (II-V) and Strong Progressions

"Two-Five," Something to Learn Along with Avoid Notes

This time, before learning the rest of avoid notes, let's learn a famous, frequently used chord progression: "two-five (II-V)" .

It's a step forward in terms of expanding your range of chord progressions, but it is also unavoidable for understanding the avoid note of IIm (IIm7).

IIm (IIm7) as a Substitute for IV (IVmaj7)

So far we have introduced cadences formed only with the three primary chords of the major diatonic chords, but of course songs don't use only those three chords.

In Lesson 28, we said that "other chords can also have functions similar to these."

28. The Three Primary Chords and Their Functions 1
Understanding chord functions to create development. This time, we look at how to use the major diatonic chords we have learned so far to create "development" and songs with a "sense of story"

In other words, the primary chords can be replaced by other chords.
Chords that can replace them in this way are called "substitute chords".

We'll introduce substitute chords in general, along with practical ways to use them, in future lessons, but this time we cover using "IIm (IIm7)" as a substitute for the subdominant (SD) "IV (IVmaj7)."

Let's use the T → SD → D → T from Lesson 31 as a sample.

It was the typical cadence that moves from stability to the next development, then returns after tension to give a sense of relief.
Now, let's change F, the SD, to Dm7 and listen.

The overall mood doesn't seem to change much, but because the chord has changed, it has a slightly different flavor from when it was F.
That's also why it's called a "substitute."
Be sure to try it with other cadences too.

The flow using this substitute chord is written in Roman numerals as follows.

Some of you may have noticed from this diagram already: the part connected in blue is the progression in a major key called "two-five (II-V)."

"Strong Progressions" Underpin the Importance of Two-Five

So why is this flow specially called "two-five"?
Let's compare another sample.

Key = C major: IVmaj7 → V7 → I (Fmaj7 → G7 → C)

Key = C major: IIm7 → V7 → I (Dm7 → G7 → C)

Both give the impression of heading toward a climax, but if you listen while focusing on the root notes, some of you may have felt that the latter has a more powerful chord progression.

Now let's focus on how the root notes move.

This sequence of root intervals looks familiar.
That's right: it's the counterclockwise movement that appeared with the circle of fifths in Lesson 6.

This counterclockwise interval was a P4th up (5 half steps up) or a P5th down (7 half steps down).

6. The Circle of Fifths
The circle of fifths is a handy chart that shows each key and the notes basically usable in each key. Look at the outside. The letters on the outside are the M (major

In this way, the root of a chord moving a P4th up (5 half steps up) or a P5th down (7 half steps down) is called a "strong progression".

It is a classic chord progression, and among the many possible chord progressions, it tends to move naturally and, as the name suggests, makes it easy to achieve strong connections and a sense of story.

The following example is made entirely of strong progressions.

Em7 → Am7 → Dm7 → G7 → C

It feels like it's progressing in a very clear way.

Looking at it this way, the flow from G7 to C is actually a strong progression too.
That's why the Dm7 → G7 → C (IIm7 → V7 → I) flow shown above is also called "II-V-I (two-five-one)".

Two-five, which introduces a strong progression using "IIm (IIm7)" as a substitute for the subdominant, is used frequently in all kinds of songs.
Of course, the IV → V flow is also used often, so get a feel for the difference in mood as you analyze songs.

Next time, building on this lesson, we'll continue explaining avoid notes, so make sure you understand this well.

Frequently Asked Questions

Q1. Specifically, what kind of chord progression is two-five (II-V)?

In a major key, it is a progression that starts on IIm7, passes through V7 and finally resolves on I major. In C major, for example, it is Dm7 → G7 → C. It gets its special name because IIm7, which has a subdominant function, works as a substitute chord and forms a strong progression.

Q2. What is a strong progression?

It refers to the root of a chord moving a P4th up (5 half steps up) or a P5th down (7 half steps down). This way of progressing creates a classic, natural flow and gives songs strong connections and a sense of story, so it is used extensively in all kinds of genres.

Q3. What is the difference between the IV → V progression and the IIm7 → V7 progression?

Both have a subdominant function, but the IIm7 → V7 progression forms a strong progression, so the roots sound more powerful. Using IIm7 gives a subtly different mood and a more modern sound, so choose between them according to the needs of your song.