The way I understand the melodic minor scale — with its raised 6 and 7 ascending and lowered 6 and 7 descending — is that it's representative of how composers operated when composing in minor.

However, at the level of casual speculation, it also seems plausible that the raised sixth in minor was a holdover from modal composition — dorian specifically.

Did the tendency to raise the sixth evolve out of dorian, or did it evolve as an artifact of major/minor tonality?

Put another way: did dorian evolve towards minor by keeping its raised sixth when ascending and then adding a raised seventh?

  • 1
    I thought it was to lose the three semitone gap that is present in the harmonic scale notes - between 6 and 7 - making melodies flow better, whether from melodic (hence the name) or Dorian. Glad I mentioned it anyway...
    – Tim
    Mar 28, 2022 at 7:31
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    @Tim there was never a theoretical mode with a three-semitone gap; remember that the three forms of minor scale were invented in the 19th century (when people started practicing scales). In counterpoint, you'd use a raised sixth degree if there was a second degree sounding and a lowered one if there was a third degree (e.g., in D minor/Dorian, B natural against E and B flat against F). The need to avoid the augmented second just means that the voice with the lowered sixth must go down, not that it must instead sing a raised sixth.
    – phoog
    Mar 28, 2022 at 10:23

2 Answers 2


First, it may help to consider how a composer like Monteverdi understood mode. Many modern theory textbooks treat modes as an ossified collection of pitches; a mode has its seven pitches, and that's that. But ca. 1600, composers understood mode not as a rigid collection of pitches but rather as a combined matrix of both the final tonal area and the possible subsidiary tonal regions of a composition.

With this in mind, let's consider Dorian and Aeolian and what they mean for these subsidiary tonal regions. Aeolian, with its lowered sixth scale degree, really inhibits the ability to move to the dominant (if you'll allow me to use some more modern terminology). In C Aeolian, for instance, the typical presence of that A♭ inhibits a dominant-to-tonic resolution to G. But Dorian—with its raised sixth scale degree—easily allows this motion to the dominant. To put it into more modern terms, this A♮ in the key of C Dorian fits into the V/V, allowing a cadence into the dominant; the A♭ of C Aeolian does not.

As such, it seems that modern minor tonality did not evolve from Aeolian, despite their similarities in scale structure. Rather, modern minor evolved from Dorian on account of that malleable sixth scale degree and the subsidiary harmonic regions that it could effect.

And we see further evidence of this evolution in notation up until the middle Baroque: in minor works, we often find a key signature with one flat too few (or one sharp too many), in effect removing this lowered sixth scale degree, creating what many today refer to as "Dorian key signatures."

All of this to say: the tendency to raise this sixth scale degree is a holdover from prior modal tradition, and is specifically a remnant of Dorian as an evolutionary predecessor to modern minor tonality. Inclusion of the raised seventh scale degree was common practice, even in the modal tradition, when cadencing, so this too would be a modal remnant.

If you're curious to read more about this, I strongly recommend Susan McClary's Modal Subjectivities. It's the go-to book for this repertoire and this thought process, it's eminently readable, and frankly it's just a lot of fun with a lot of great music.

  • To clarify: in the key of C, Ab facilitates movement to G-as-new-tonic; whereas, A facilitates movement to G as dominant?
    – Aaron
    Mar 27, 2022 at 21:43
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    A bit of the reverse: the A-flat keeps the G sounding as dominant, but the A-natural of Dorian helps create a modulation to G as a new tonic.
    – Richard
    Mar 27, 2022 at 23:19
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    I haven't found an example, but I did see some time ago comments that, in minor keys, both sharps and flats had one less. This seems backward for "sharp" minors (E minor, B minor, etc.). I did count a the number of accidentals in some minor key Baroque pieces and found that the traditional and "one flat less" key signatures too about the same number of written accidentals.
    – ttw
    Mar 28, 2022 at 13:14
  • @ttw Oh, interesting! So E minor written with this key signature would require both C-sharps and F-sharps?
    – Richard
    Mar 28, 2022 at 13:18
  • Strange. An extra sharp would probably be equivalent to modern practice. The parallel minor adds three flats (or equivalent) so minor key notation probably doesn't concentrate on sharp usage. For Baroque music, I'd guess that B minor is as "high" (sharpy?) as most pieces go. Modern practice is easy to read in that the relative minor needs no signature change. Bartok's non-systematic stuff isn't that easy to read but that may be lack of practice on my part.
    – ttw
    Mar 28, 2022 at 16:05

Did the tendency to raise the sixth evolve out of dorian, or did it evolve as an artifact of major/minor tonality?

Historically, neither. Rather, the historical starting point is Dorian, which was, along with its plagal counterpart hypodorian, one quarter of the 8-mode system that arose in the medieval period. The other three parts of this system were the plagal and authentic modes that correspond to the modern Phrygian, Lydian, and Mixolydian modes.

The tendency to lower the sixth was one of the major factors leading to the evolution of the twofold major/minor tonal system. Others were the tendencies to raise the leading tone of both Dorian and Mixolydian and to lower the fourth degree of Lydian.

The Aeolian and Ionian modes were only "invented" (as theoretical artifacts) in the middle of the 16th century with the publication of Glarean's Dodecachordon in 1547. But centuries earlier, even without considerations of harmony or counterpoint, untransposed monophonic chant in the Dorian mode could use B♭ as the upper neighbor of the dominant (for example in the Kyrie orbis factor, which appears in a 13th-century manuscript, so it is at least that old).

Contrapuntal considerations increased the pressure to lower the sixth degree of the Dorian mode, as well as to raise the leading tone (of both the Dorian and Mixolydian modes). But these pressures were contextual, so the alterations did not necessarily apply everywhere in any given piece. This contextual element survives today in the existence of the various forms of the minor scale.

These modifications were treated as conventions applied to the older system without being part of it, strictly speaking ("musica ficta"). There was no place in Guido's system for sharps, yet they were in common use by the sixteenth century (although not yet in key signatures). By the 16th century, people were writing music that can for the most part be described using modern tonal harmonic theory. Glarean's theoretical innovation was an important step toward formal recognition of these conventional extensions of the modal system that would lead to the two modes, major and minor, of tonal harmony.

After Glarean, we started to think of the underlying mode of minor keys as being Aeolian. But this happened slowly. Even two centuries later, it was very common for minor-key pieces to have Dorian key signatures; a famous example is Bach's "Dorian" toccata and fugue in D minor with no flats or sharps in its key signature. It has been given this name even though the other famous toccata and fugue in D minor also has the same key signature. (Modern editions of such pieces typically add a flat to the key signature.)

Put another way: did dorian evolve towards minor by keeping its raised sixth when ascending and then adding a raised seventh?

You could say this, but putting it in terms of lowering its sixth when descending might be more precise. More generally, one should probably say that there has always been some instability around the identity of the sixth degree of the Dorian scale. This started as a tendency to lower it, first as an upper neighbor and later more generally when descending. With the advent of counterpoint and harmony, the identity of the seventh degree also became ambiguous. Then Glarean came along and gave us a new, distinct mode that we could use to describe cases where the sixth degree is lowered, so it was no longer necessary to think of that B♭ as an alteration to the Dorian mode; instead, we could think of the piece as being in transposed Aeolian mode.

This wasn't as neat and tidy as it might seem, however, because of the common use of both the lowered and raised sixth degree in most pieces. Real music uses both, so it isn't necessarily clear whether a piece is in Dorian or Aeolian, but but whichever one we choose, we have to allow for the fact that it will be altered frequently. Glarean simply formalized a long, slow shift in which people came to see the base set of unaltered pitch classes as Aeolian rather than Dorian.

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