What actually constitutes a diatonic scale?

Trying to do my own homework here! I've read that only the standard major scale is diatonic. Also, I've read that the harmonic and melodic minor scales are also diatonic. Also I've read that the notes from any scale can be called diatonic to that scale. I've always gone with the first two definitions, but I've been wrong before! With such conflicting views, is there a definitive definition?

• Don't the answers to this question answer your question? Dec 26, 2017 at 18:08
• @MattL. - they would have done, but I have read several conflicting definitions, so now, I'm asking the question to further enlighten myself and others. It is certainly an answer to the question.
– Tim
Dec 26, 2017 at 18:34
• With such conflicting views, is there a definitive definition? Perhaps your question provides its own answer: No, there is no definitive definition. Who would you expect to define it and make it "the law of the land"? Beethoven? Stravinsky? Thelonious Monk? Phillip Glass? It's clearly one of those fuzzy terms - everyone uses it and no one knows exactly what it means, but from the context its meaning is (hopefully) understood. the notes from any scale can be called diatonic to that scale - that's how I use it lately. Sometimes I am corrected, but now I stopped worrying about that... Dec 26, 2017 at 19:31

https://www.britannica.com/art/diatonic

Diatonic, in music, any stepwise arrangement of the seven “natural” pitches (scale degrees) forming an octave without altering the established pattern of a key or mode—in particular, the major and natural minor scales.

I emphasized the in particular to show that it doesn't necessarily apply to just the major and natural minor scales.

The way I understood it, diatonic described a note's relationship to a scale/chord. In other words, C# is not a diatonic note in the G major scale, but D is; F# is diatonic in the C Lydian mode, but G# is not.

• I emphasized the in particular... - +1 for that. The way I understood it, diatonic described... - that doesn't seem to be what it says in the definition you cited but no matter - we certainly use it that way. I also often wonder how authoritative a generic resource like Britannica can be when it comes to something so specialized and idiosyncratic as musical terminology. Dec 27, 2017 at 7:42

A common definition for the Diatonic Scale is that of the Major Scale or the Natural Minor Scale. However, the word diatonic is often used generically and is not as strictly defined as, say, the Major Scale.

So, for instance, many will refer to any mode of the Major Scale as being diatonic. You will also see many theorists referring to the various triads (and other chords) built from the Major Scale as being diatonic.

So, in short, the term Major Scale is more specific and strictly defined than the more generic word Diatonic (although the term Diatonic Scale almost always means, or implies, the Major Scale).

• The most common definition of the Diatonic Scale is that of the Major Scale - is that the most common usage? I hardly think so. How did you arrive at this conclusion - you checked a lot of dictionaries? Any other sources besides wikipedia - perhaps some authoritative scholars? The OP, who is quite knowledgeable, has already mentioned reading differently in various sources - what is it about this answer makes it more correct than the other definitions the OP has mentioned? Dec 26, 2017 at 19:26
• Fair enough, I can't say that I counted every possible resource. However, doing simple search of "Diatonic Scale" in google and reading through the first 5 entries (1 of which was the Encyclopædia Britannica) showed that they all defined a diatonic scale as consisting of the notes of the Major scale (or Natural Minor scale). And that was the point I was attempting to make. I'll edit the opening sentence of my answer to reflect that. Dec 26, 2017 at 21:54

The definitive definition would probably be based on the scale the name implies, and its historical origin, from the Ancient Greek and probably pythagorean diatonic scale.

The confusion may come from the colloquial use of the term, which includes using Major scale as a base, or includes scale modifications such as Harmonic Minor.

From what I remember, my college theory class defined the diatonic scale as specifically comprised of a pattern of whole tones and semitones, with the semitones fully separated.

The Harmonic Minor scale used in a melodic context (playing the augmented second jump from the minor 6th to the major 7th in the melodic line) would not be considered true diatonic, but a modified scale. Used Harmonically where the raised 7th degree of the scale is used in context and as part of a Dominant chord and not used as a leading tone to the tonic, then the Harmonic scale could be described as diatonic.

To quote Grove's Dictionary of Music: "Diatonic (from Gk. dia tonos : ‘proceeding by whole tones’ ) Based on or derivable from an octave of seven notes in a particular configuration, as opposed to Chromatic and other forms of Scale . A seven-note scale is said to be diatonic when its octave span is filled by five tones and two semitones, with the semitones maximally separated, for example the major scale (T–T–S–T–T–T–S). The natural minor scale and the church modes ( see Mode ) are also diatonic."

So, specifically five tones and two semitones. At least, that's how I learned it.

• Which then makes the Lydian mode a perfect candidate, with the same premise being fulfilled - T-T-T-S-T-T-S.
– Tim
Apr 16, 2019 at 6:43