Functionality
Functionality is the idea that every every chord in a chord progression servers a particular function.
A typical chord progression (that sounds interesting) will create and then resolve tension. This is where functionality comes in. Some chords create tension and some chords do not. Another way of saying this is that some chords are dissonant and some are not. So we created three categories of chords: Pre-dominant (AKA Subdominant), Dominant and Tonic. All the diatonic chords in a particular key can be assigned to one of these three specific functions. Chords in each of these categories produce differing amounts of ‘tension’ and each have a different ‘feel’. They are summarised below (in the key of C Major):
| Function | Tension | Chord |
|---|---|---|
| Tonic | None | CMaj7, Em7, Am7 |
| Dominant | Lots | G7, Bø7 |
| Pre-Dominant | Some | Dm7, FMaj7 |
Each chord in each category is just a substitution of the other chords in that category (Em7 and Am7 are both Median Note Substitutions of CMaj7).
- Tonic: Em7 = rootless CMaj9; Am7 = C6
- Dominant: Bø7 = rootless G9
- Pre-Dominant: FMaj7 = rootless Dm9
Below I have written out all the chords in the key of C Major with their scale degree names and associated chords & functions.
| Degree | I | II | III | IV | V | VI | VII |
|---|---|---|---|---|---|---|---|
| Name | Tonic | Super-tonic | Mediant | Sub-dominant | Dominant | Sub-mediant | Leading tone |
| Note | C | D | E | F | G | A | B |
| Chord | CMaj7 | Dm7 | Em7 | FMaj7 | G7 | Am7 | Bø7 |
| Function | Tonic | Pre-Dom | Tonic | Pre-Dom | Dom | Tonic | Dom |
As stated earlier, an interesting sounding chord progression would start with a little bit of tension (pre-dominant), adds more tension (dominant), and then resolves that tension (tonic). This creates a sense of harmonic movement and a story-like narrative (see below). Consequently, a typical chord progression follows the following standard template progression:
Pre-Dominant → Dominant → Tonic
II-V-I
Playing chord progressions is just like improvising a melody or writing a story. You want to start with a little bit of tension (Pre-Dominant), build on that tension (Dominant), and then finally resolve that tension towards the end of the story. Following the above template progression you can use any chord from each category and still create a strong sounding progression for the aforementioned reason. Many of our most common chord progression follow this template – for example a IV-V-I or a II-V-I. The latter is particularly important in Jazz.
| Pre-Dom | Dom | Tonic |
|---|---|---|
| Dm7 | G7 | CMaj7 |
| FMaj7 | G7 | Am7 |
| FMaj7 | Bø7 | Em7 |
Further to these basic diatonic 7th Chords, you can then extend, alter, borrow or substitute the chords and still stay true to this template progression structure. Put another way, if you replace a diatonic chord with a substitution or borrowed chord the new chord still retains the original chord’s function. All the below chords are often seen in chord progressions which still follow this basic functional logic and structure.
| Pre-dominant | ||
| Base Chord | Substitutes | Reason |
| Dm7 | D7 | Dominant Substitute |
| Dø5 | Minor II Substitute | |
| Do7 | Diminished Substitute | |
| A♭7 | Tritone Substitution | |
| D♭Maj (Fm#5) | Neapolitan sixth | |
| FMaj7 | Fm7 | Minor Substitute |
| F#o7 | Diminished Substitute | |
| F#ø7 | Leading Tone Substitute | |
| Dominant | ||
| Base Chord | Substitutes | Reason |
| G7 | G9/♭9/13 | Extension/Alteration |
| D♭7 | Tritone Substitute | |
| E7 or B♭7 | Minor 3rd Substitute | |
| G7sus or G7sus♭9 | Sus/Phrygian Chord | |
| Bø7 | Bo7 | Diminished Substitution |
| Tonic | ||
| Base Chord | Substitutes | Reason |
| CMaj7 | CMaj9#11 | Extension/Alteration |
| C69 or C69#11 | ||
| Cm7 | CmMaj7 | Extension/Alteration |
| Cm6 or Cm69 | ||
| C7 (Blues) | C13 | Extension/Alteration |
| C7#9 or C7♭9 | ||
| Deceptive | Am7 | Tonic Substitute |
| Em7 | Tonic Substitute | |
| FMaj7 | Back to Predominant | |
| Other | NA | |
When analysing a chord progression, your goal is to try break it down into smaller components. A II-V-I is one such component. You will find them everywhere. They are the building blocks of Jazz harmony.
This is an important concept to understand, because it will lead us to a discussion about ‘non-functional harmonies’ in future lessons.
Instability
There is some logic to why these chords have been allocated into these specific functions. Not all notes in a Major scale are equal, some are more unstable than others. The 4th note of the Major scale is considered particularly unstable (if you’re interested in why this is the case see my Lydian Chromatic Concept and Acoustics videos.
- Pre-dominant functioning chords have some tensions because they contain the 4th of the Major key.
- Dominant functioning chords have a lot of tension because they contain both the 4th and the 7th of the Major key – these two notes create a tritone interval, which is considered a very dissonant interval.
- Tonic functioning chords do NOT contain the 4th of the Major key.
Minor Keys
So functionality makes sense and has some logic to it in a Major key. Unfortunately, when we change over to a minor key, this logic breaks down. But because this structure works so well in Major keys and has been so widely used we got used to hearing chord progressions that follow this template progression. We are used to hearing the II chord as a pre-dominant, and the V chord as a dominant. So we just took the same structure and shoved it into the minor tonality, even though it doesn’t fit. So the degrees in a minor key all serve the same function they would in a Major key.
| Function | Chords |
|---|---|
| Tonic | Am7, CMaj7, FMaj7 |
| Dominant | Em7, G7 |
| Pre-dominant | Bm7b5, Dm7 |
But this doesn’t make sense anymore. The II chord is now a m7b5, which has a tritone interval in it and thus should be a dominant. The V chord is a m7 chord – not dissonant at all! To partly fix this issue, we invented the harmonic minor scale (which has a #7 compared to the natural minor) so that the V chord now becomes a dominant.
| Function | Chords |
|---|---|
| Tonic | AmMaj7, CMaj7#5, FMaj7 |
| Dominant | E7, G#o7 |
| Pre-dominant | Bm7b5, Dm7 |
This awkward tacked-on solution made minor functionality work…ok. It’s not perfect and it’s no longer logically consistent, but it sounds good enough so we use it. This ‘solution’, however, came at the cost of added complexity. We now have two minor scales (and two sets of chords) to account for when creating/analysing minor key chord progressions. A minor chord progression can ‘borrow’ chords from either minor scale. And then someone just had to come along and create the melodic minor scale!…Check out the below videos for a further discussion on this topic.
So functionality is really a Major scale concept that has been uncomfortably shoved into minor tonality. It no longer makes sense in a minor key, but sounds good enough so we just ignore the inconsistencies and pretend everything is ok. Just smile and nod and keep on keeping on.
Have a Listen to
- Autumn Leaves ~ Joseph Kosma
- Afternoon in Paris ~ John Lewis
- Satin Doll ~ Duke Ellington
- Solar ~ Miles Davis
- Tune up ~ Miles Davis
- Every Pin Pan Alley Song Ever Written
Major Functionality
Minor Functionality