While much has been written in musical publications in the past about Modes, by far the most common question asked by guitarists seems to be along the lines of "OK, I've learnt the modes, but how do I use them?" The trouble with the modal analysis of improvisation is that descriptions usually relate to analysis of what happened (hindsight), rather than on how to make it happen (foresight). To put it another way, the inference made by modal analysts is that the process of deconstruction of an improvisation is the same as that of construction. A better way of looking at improvisation is to incorporate the rarely discussed study of Chord Function.
What is Chord Function? Chord Function is the study of the function of chords in a chord progression. Every chord has a function. If a musician can identify the function of a chord, then the application of scales, modes, arpeggios, or any technique becomes simple, effective, and excitingly surprising.
To study chord function, we need to know a little about Harmony.
Let’s have a look.
Take a C major scale - 1C 2D 3E 4F 5G 6A 7B
A chord consists of three or more notes taken from a scale. These notes are most often the 1st, 3rd, and fifth notes from any scale point. It is possible to go further into this idea, taking also the 7th, 9th, 11th, and 13th notes as well, but for the time being, we will look at three note (triads) and four note chords.
If we take CEG (135) of C major, we get a C major triad, DFA (246) spells D minor, EGB (357) spells E minor, FAC (461) spells F major, GBDF spells G dominant 7, ACE (613) spells A minor, and BDF (724) spells B minor 7b5.
If a player is confronted by a chord progression which is, for example, C ma / A mi / D mi / G7, then the Chord Function player's thought process goes like this:
These chords are all in the key of C major - they have been made from notes in the C major scale. The C ma is functioning as a I chord in the key of C major, the A mi is functioning as a VI chord in C major, the D mi is functioning as a II chord in C major, and the G7 is functioning as a V7 chord in C major.
For improvisation over these chords, the scale of C major is therefore appropriate.
How does this relate to modal thinking? The C major scale as played from the 8th fret (root note C on the 6th string) is called the I major scale. Modal theorists call this the Ionian mode. The C major scale played from the 10th fret root 6 is the D II minor scale (D Dorian), C major from E at the 0 or 12 frets root 6 is the E III minor scale (E Phrygian), C major from F at the 1st or 13th frets root 6 is the F IV major scale (F Lydian), C major from G at the 3rd or 15th frets is the G V7 dominant scale (G Mixolydian), C major from A at the 5th or 17th frets is the A VI minor scale (A Aeolian), and C major from B at the 7th or 19th frets is the B VII mi b5 scale (B Locrian).
All these modes contain the notes of C major, so any one, or all of them will work for improvisation in that key. So for guitarists, it's better for them to think that the modes give them positions in which to play a key, rather than scales to play over a chord. Really, we have a philosophical shift in approach here. A modal improviser is reactive - their improvisation is a reaction to the chords. A chord function improviser is pro-active - the improvisation is supported by the chords. It is also better for guitarists to eventually forget the modal names for these positions (Ionian, Dorian, etc) and replace them with names that carry more information - I major, II minor, etc.
As an experiment, try recording the progression mentioned above. If you are a struggling modal player, as the recording is playing back, improvise using the C Ionian mode, then the D Dorian, then the E Phrygian, then F Lydian, then G Mixolydian, then A Aeolian, the B Locrian - each one for the entire progression. The important concept here is to improvise. Don't just play the scales. You will find that all of them work. It is not necessary to restrict yourself to the C Ionian over the C major chord, then change to the A Aeolian for the A minor, etc. In fact this why many modal players complain that the modes sound dull or unimaginative.
Each of the scale positions has its' own sound because of the different intervals that lie under the fingers. As a guitarist becomes more skilled with position playing, these sounds can be used for different concepts for improvisation. For a blues sound, try A VI minor at the 5th fret over these chords. For the adventurous, try A blues licks! (This is what Clapton, Slash, Gilmore and others do). For a dark minor sound, try E III minor at the 12th fret. The point is that all of them work, and to experiment and make up your own mind.
It is important to analyse chord progressions to eventually be able to see what key the chords are functioning in, and to then see those positions on the fretboard. This takes practice, and its not always a single solution. For example, a single D minor chord can have three functions; i.e. in three (or more) keys - II in C major, III in Bb major, and VI in F major. Other chords around it are needed to make a decision.
Of course, the chord progression we used as our workshop is a bit dull. One popular progression to workshop with, is the progression from the solo of "Cocaine". Make a recording of the triads going DDCD / C / a few times. So many players try to improvise using some sort of D Blues scale. But a chord function player will see that these chords are IV ma and V7 in the key of G major. Try playing any or all the G major scale positions over these chords. It's amazing how good the simple G I major scale at the 3rd fret sounds! The other choices are A II mi at the 5th fret, B III mi at the 7th, C IV ma at the 8th, D V7 at the 10th, E VI mi at the 12th , and F# mi b5 at the 2nd or 14 frets.
So the point is that it is very restrictive in a real improvising situation to apply individual 'modes' to individual chords. The modal system can be used as a means of explaining why the notes chosen work, but over a moving chord progression, they become fairly meaningless. Far better to be able to see what key the chords are functioning in, and play in any or all of the appropriate