An Introduction to Modal Theory

As we observed when using formulas to build major scales, the pitches in a major key have a mathematical relationship to each other.  Each scale degree is a certain number of half steps away from another scale degree and we call this distance an interval.  This relationship remains constant regardless of what pitch we base the major scale off.  The distance between the major third and perfect fifth in a given key is always three half steps (also known as a minor third) in all twelve major 


Formula     W           W         H   W W   W       H

C major    C          D           E          F          G         A         B         C

Interval     R         M2        M3       P4         P5      M6       M7      P8

We also learned that by beginning on the sixth degree of the major scale and proceeding through the same formula, we can construct the natural minor scale.  This is called the major key’s relative minor.  By using the major scale formula but beginning from a different point we have created a key that has the same pitches but a contrasting character, otherwise known as its tonality.  C major, a bright key, becomes a A minor, a somber one.  Simply taking the same key and centering the melody and harmony around a different pitch transforms the tonal quality of a scale structure.

Formula     W           H         W   W       H   W       W

A minor   A          B           C          D          E         F         G          A

Interval    R         M2        m3        P4        P5      m6       m7       P8  

This concept is the foundation of modal theory.  However, in modal theory, key centers are constructed from every degree of the major scale.  Each possesses its own  unique tonal character resulting from its intervallic relationships and its own “characterisitic pitch” (except Lydian), an interval that provides this character and requires special handling.  Each also has it own name so that this character can be identified regardless of its parent scale (the relative major key from which it is constructed) as well as a characteristic chord progression.  This allows a drastic expansion of improvisational and compositional vocabulary.

The names and major scale root of the modes are as follows:

I   Ionian   (Major)

II  Dorian

III Phrygian

IV Lydian

V  Mixolydian

VI Aeolian

VII Locrian

How a student learns to concieve of modes is very, very important and is one the most mishandled concepts in all of guitar pedagogy.  Done the wrong way (rooted on the E and A strings with only two fretboard pattern for each mode), it can be one of the most hampering mis-steps a guitarist can make, frustrating later attempts at chord-scale improvisation and fretboard understanding.  I’ll admit that fear of this pitfall has led me to avoid teaching modes for a long time.  In this unit, we will use a CAGED approach to each mode so that each can be paired with corresponding arpeggios, chords and other structures.  We will spend ample time on each mode to ensure it is well mastered and understood before proceeding to the next mode.

Exercise One.  Name the parent scale (major scale) of each mode.

1. D Dorian ____________________

2. B Phrygian __________________

3. G Lydian ____________________

4. F Mixolydian _________________

5. D Aeolian ____________________

6. D Locrian ____________________

7. F# Phyrgian __________________

8. Bb Mixolydian ________________

9. Eb Dorian ____________________

10. D Lydian ____________________

11. A Locrian ___________________

12. C# Ionian ___________________

13. F Aeolian ___________________

14. G Ionian ____________________

Exercise 2. For each parent scale and scale degree (shown as a roman numeral), name the corresponding mode and its root.

  1. C major  II ______________
  1. A major IV ______________

3.   G major III _______________

4.   F major V ________________

5.  Eb major VII _______________

6.  D major I __________________

7.  B major V _________________

8.  E major II _________________

9.  Db major III _______________

10. F# major IV _______________

11. E major VI ________________

12. Ab major V _______________

13. Gb major I ________________

14. F major VII ________________

Exercise 3. Use the major scale formula to derive the formula for each mode.

Ionian ________________________