What Is a Mode? Scales That Differ by Where the Home Note Sits

A mode is defined by the pattern of intervals between successive notes rather than by which notes are used. Taking the same collection of seven pitches and treating a different one as home changes where the semitone steps fall relative to that home, which changes the character entirely, since the relationship between the home note and each other note is what the ear responds to. The familiar major scale is one such arrangement and the natural minor is another, so the modern system is a subset of the modal one rather than a replacement for it. Playing a scale and then playing the same notes starting from a different point demonstrates the effect immediately, and hearing the difference is entirely a matter of which note the ear takes as the reference, which is established by emphasis and by where phrases come to rest.

Each has a name inherited from medieval theory and a recognisable character:

• •Ionian, identical to the major scale, bright and settled
• •Dorian, a minor arrangement with a raised sixth, which gives a distinctive quality used constantly in folk music and in jazz
• •Phrygian, with a lowered second, which produces a Spanish and Middle Eastern association
• •Lydian, a major arrangement with a raised fourth, which sounds floating and is a staple of film scoring
• •Mixolydian, major with a lowered seventh, which is the sound of a great deal of rock and blues
• •Aeolian, identical to the natural minor, and Locrian, which is unstable and rarely used because its home chord is dissonant

The names are Greek and the arrangements they label are not the ones the Greeks meant, which is a confusion introduced in the medieval period and never corrected. Greek theory used the terms for different structures, and a misreading of a late classical source attached them to the church modes of European chant, which had their own system involving a final note, a reciting tone and a range. That medieval system is what the modern names descend from, and it worked differently again, since a mode there was a framework for melody rather than a scale to improvise over. The major and minor system consolidated in the seventeenth century and displaced the rest for roughly three centuries, after which composers and performers deliberately revived modal writing, which is the immediate source of most current use.

The seven arrangements from a single seven-note collection are one family and modal thinking extends well past them. Harmonic and melodic minor scales generate their own sets of modes, several of which have acquired names and regular use in jazz. Pentatonic scales, using five notes, produce their own rotations and are the basis of an enormous amount of music worldwide. Indian classical music uses a far larger and more structured system in which a raga specifies not only a set of pitches but characteristic phrases, ornaments, ascending and descending forms and associations with times of day, which is considerably more than a scale. Arabic and Turkish traditions use systems including intervals smaller than a semitone. Treating those systems as exotic versions of European modes misdescribes them, since each carries rules about melodic behaviour that a scale does not.

Modal thinking is standard in several current practices and each uses it differently. Jazz improvisation was reorganised around modes in the mid twentieth century, with pieces built on a small number of scales held for many bars rather than on rapid chord changes, which changed what improvisers were doing. Folk traditions across Europe and beyond never abandoned modal melody and supply most of the living examples. Rock and blues use particular modes so consistently that the sound is identified with the genre rather than with the theory. Film scoring uses specific modes for specific associations, which has made a few of them cues rather than colours. The practical point for a player is that a mode is established by treating a note as home, which requires the accompaniment to support it, and playing the notes without that context produces the original scale rather than the mode.

The same seven notes with a different home note put the semitones in different places relative to that home, which changes the character entirely. Major and minor are two of the arrangements rather than a separate system. The Greek names were attached to the wrong structures by a medieval misreading. A mode only exists if the accompaniment establishes the home note, otherwise the notes are just the original scale.