Chapter 8:

Major key harmony

What is a major key?

The vast majority of songs in Western music are written in a major key.

Songs in a major key use notes and chords derived from the major scale, with a special emphasis on the first scale degree: the “tonic” or “keycenter”, the note the key is named for.

Major key compositions treat the tonic as home, a point of reference and a point of rest, and typically use the tonic note more frequently than any other note in the scale.

Music that revolves around a tonic in this way is called “tonical”. (Or, unfortunately, “tonal”. See “tonal” in the glossary for argument against that usage.)

Chords in a major key

The chords in a major key are determined by harmonizing the major scale. See Chapter 6. Introduction to Western harmony for details.

Notice that in a major key:

• the I, IV, and V chords are always major,
• the ii, iii, and vi chords are always minor, and
• the vii chord is always a diminished triad.

The chords derived from the scale in this way are called “diatonic” chords, meaning the chords that are “in” the key.

Playing in position

It’s useful to be able to play all the chords in a key in one “position” on the fretboard. This means that all chords are found within the same span of four or five frets, so all chords can be played without moving the fretting hand up or down the guitar neck.

This makes chord progressions easier to play, and helps us develop an intuitive understanding of how the chord tones relate to each other.

It also makes for smooth “voice leading”, meaning the chord tones change only by small intervals from one chord to the next, as they would if composed for singing by a choir of human voices.

A useful, movable way to identify fretboard positions is by specifying the CAGED shape used for the I chord, resulting in five different positions.

C shape I chord position

Practicing these chords

Ascending and descending

When first getting familiar with the chords in a position, it’s helpful to start by focusing on the underlying major scale, and playing the chord having a root on each scale degree in ascending or descending order. For example:
I-ii-iii-IV-V-vi-vii°-I
(C-Dm-Em-F-G-Am-B°-C)
I-vii°-vi-V-IV-iii-ii-I
(C-B°-Am-G-F-Em-Dm-C)

By knowing the major, minor, and diminished chord shapes, and knowing which type of chord has its root on each degree of the major scale, it’s easy to assemble each chord on each scale degree, without having the whole position memorized.

Primary and secondary chords

In a major key, the major chords (I, IV and V) are called “primary chords”.

These three chords, called the “tonic”, “subdominant”, and “dominant” in euroclassical terminology, are enough to create a full and rich chord progression by themselves. A surprising number of popular songs are composed of only these three primary chords.

It’s therefore helpful to practice various chord changes with the primary chords. For example:
I-IV-V-I (C-F-G-C)

The minor chords (vi, ii, and iii) are called “secondary chords”.

The secondary chords have the same relationships to each other as the primary chords do. The vi can act as the tonic, the ii as the subdominant (a perfect fifth below the vi), and the iii as the dominant (a perfect fifth above the vi).

Example secondary chord progression:
vi-ii-iii-vi (Am-Dm-Em-Am)

Circle of fourths/fifths

It can be helpful to practice chord changes in order of ascending fourths (aka descending fifths). It’s a pleasant sounding chord progression that can cycle around endlessly. For those intending to play jazz, it also contains the most common chord changes in most jazz music.

The circle of fourths/fifths:
I-IV-vii°-iii-vi-ii-V-I
(C-F-B°-Em-Am-Dm-G-C)

Playing songs in one position

Possibly the most useful way to practice these chords is to practice chord changes for major key songs we already know, without moving out of one position.

This helps make the chords more real and less abstract, and begins to integrate them into our actual playing.

More about major key harmony

The dominant V7

In major key harmony, the V chord is often played as a “dominant seventh chord” (sometimes referred to as simply a “seventh chord”). A dominant seventh chord is a major triad with an added minor seventh interval. It’s notated by simply adding a “7” to the chord symbol, like “G7” or “V7”. See Chapter 11. Seventh chords and drop voicings for more information.

The V7 chord is constructed by stacking another third onto the V triad, like this:

Dominant seventh chords are tense, because they contain the highly dissonant tritone interval between their third and seventh factors (scale degrees 7̂ and 4̂ in the V7 chord). The V chord also contains the leading tone (scale degree 7̂), which “wants” to resolve to the 1̂ (the tonic, the I chord) according to theories of harmonic function.

In other words, the V7 chord tends to pull urgently toward the I chord in Western harmony.

The V is the only dominant seventh chord that occurs when harmonizing a major key. That’s where the name “dominant seventh” comes from. In euroclassical harmony, the V chord is called the “dominant” because it’s based on scale degree 5̂, a perfect fifth, which is the dominant harmonic in the overtone series.

In short, the “dominant seventh” is the chord type of the “dominant” chord (V) when it includes its “seventh” factor (V7).

The diminished vii°

The diminished triad vii chord doesn’t get much love, with most people dismissing it as “rarely used” or “not practical”.

But notice that it contains almost exactly the same notes as the harmonically vital dominant V7 chord.

The vii° is essentially a “rootless” V7 chord.

It contains the same tritone (between 7̂ and 4̂) and leading tone (7̂) as the V7.

As such it has nearly the same harmonic effect as the V7, and it is often exactly the right sound to drive a chord progression home. It’s easy to play, and easy to add a bass note of either the 5̂ (for a true V7 chord) or the 7̂ (for a richer diminished triad) as desired.

The diminished vii is rather practical after all.

A shape I chord position

G shape I chord position

E shape I chord position

D shape I chord position

Shapes on the whole fretboard