Distinguishing the semantics of modes and scales. When to say scale vs. when to say mode?

Question

Correct me if I am wrong: While scales are different from modes, they can share the same notes (C major and D dorian). However, they can completely shift its tonality. Say I play a melody in C Ionian, and then I play a melody in A Aeolian. Both have the key signature (same notes), yet one scale sounds more major and "bright" while the other sounds more minor and "dark." This is exactly the same difference between C major and A minor. So my take is that in a modern context of modes, you could be more specific about tonality by referring to a mode than you would with a scale. With a mode, you have 7 parameters based upon the 7 scale degrees, and you have the tonal center of that set of notes. So, one could say that A Aeolian is the C major scale with an emphasis on its 6th scale degree- Aeolian- known for being dark.

Is this a correct way of thinking about this?

Answer 1

All modes are scales, but not all scales are modes, just like all poodles are dogs, but not all dogs are poodles.

Scales are sets of notes portrayed in ordered fashion. The common, simple major scale of C is played from C to a higher C, and back - as far as exam boards (and many teachers) are concerned. The scale called chromatic uses every semitone. The pentatonic scale only uses five notes before they repeat. The whole/half diminished scale uses notes with alternate tone and semitone spaces. There are several minor scales, which differ subtly.

The point here is that any scale is an ordered set of notes, usually named from standpoints of home note, and what successive intervals they contain. TTSTTTS would be the pattern for a major scale, and if the first/home note is F#, we call it the scale of F# major.

All scales will have the propensity to have modes made from them. Taking that F# major, but starting on the second degree, G#, it gets called G# Dorian, or the Dorian mode of F#. Note the difference in name, but using the same notes. Modes, then, are the same set of notes, but centred somewhere that doesn't make them a simple major or minor scale. Dorian, for example, uses the major scale set of notes, but centres on the second degree, making it sound minor (the 3rd degree is a minor third from the root), but it doesn't follow the pattern of tone/semitone spaces that the other minors use. Phrygian follows suite, with another minor third.

Minor scales have modes too, so using the notes from, say, A melodic minor, but making root/home the second degree, (B), that becomes a mode of that A minor. It will use the same harmony, or triads, as are available from the A minor scale notes, but they will come across in a different way, keeping the home as B, rather than A.

Slight anomalies occur with Ionian mode and Aeolian mode, as they respectively, are major and natural minor scales too, but often when 'rules' are made, there are certain factions that get mixed up.

Answer 2

Is this a correct way of thinking about this?

IMO that is certainly a correct way of thinking about it, but let's get a little more detailed and specific:

If we want to take a stab at defining scale vs mode, we could say that those ordered collections of notes that have proven to be most useful as building blocks for our "modern" [call that post Renaissance, for argument's sake] music we call scales - for example "The Major Scale" "The Minor Scale", "The Melodic Minor Scale". ( @AlphonsoBalvenie in his answer refers to those as "Established Scales", a good working term IMO. ) Their alternate configurations, as will be explained - for example "Lydian Mode", "Dorian Mode", "Phrygian Mode" - those we call modes. However, that is clearly a subjective definition. An objective definition of scale vs mode differs significantly, as follows:

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There is no objective difference between a mode and a scale: Take any key signature, play any ordered collection of notes using that key signature - start on any note in the chromatic octave (which has no accidentals) and play a sequence of notes abiding by that key signature - you now have what's called a scale/mode.

Mode is a relative term: when you decide, for whatever reason, to make one particular note of your ordered collection of notes the root - the first note of your scale according to the key signature - that configuration is called the scale, and becomes a 'parent scale', as it were, to its other modes: Building a scale with the same key signature but using a different root than the 'parent' root becomes a mode: A different fashion/manner of playing the parent scale.

So using the example of C Ionian - which we call the C Major Scale, the 6th mode of that scale - a scale that starts on the 6th degree of the parent scale, (whose key signature has no sharps and no flats) in this case A - becomes the Aeolian mode, commonly known as the A Minor Scale. But note that C major also has a modal name: Ionian. In fact, if we decide that A Aeolian is the parent scale, C Ionian would then be considered the third mode of A Minor. And so it goes with all modes and scales.

Because today we tend to think of the C Major and A Minor Scales as the basis for our tonal system, everything else we refer to as "modes", but it's by no means so clear-cut, and in truth it's simpler than one might think.

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However, they can completely shift its tonality...

Correct. As you work through the different modes of a parent scale, the tonality constantly shifts - some modes have what we call major tonality, some minor tonality, and some tend to be a bit ambiguous as well - most notably dominant tonality, as will be explained. Generally how we classify tonality is determined by the 3rd and 7th scale degrees. Those distinctions are somewhat subjective, fuzzy and arbitrary, but are useful for discussion and analysis and can be helpful when developing harmonies or improvising over a mode or scale.

• Using the C Major scale (Objectively speaking, it's called the Ionian mode), the 3rd degree is E, a Major 3rd, and the 7th degree is B, a Major 7th - decidedly a Major tonality.
• Moving to the 2nd mode of C Major, built on D and referred to as the Dorian mode, the 3rd degree is F, a Minor 3rd, and the 7th degree is C, a Minor 7th - decidedly a Minor tonality.
• Moving to the 5th mode of C Major, built on G and referred to as the Mixolydian mode, the 3rd degree is B, a Major 3rd, and the 7th degree is F, a Minor 7th. This "split" or "ambigious" tonality, which creates a tritone - 3 'whole steps' or 6 chromatic tones and considered the most dissonant of intervals - between the 3rd and 7th degrees of the scale/mode - is called Dominant tonality. [Manipulating dominants in contrast to overtly major or minor scales and chords is idiomatic for creating a sense of tension and movement in the European/Western traditional musical system. Almost all rock, blues and jazz emphasizes dominants, which makes those genres both very flexible and often quite difficult to analyze according to the traditional rules of harmony.]

Aside from the tonality of the scale/mode with reference to itself, the diatonic chords, and therefore diatonic harmonies, also shift as modes change. For example:

• The diatonic 7th chord for the root note of C Major (C) is comprised of C-E-G-B - a Major 7th chord: Both the 3rd and the 7th are major.
• The diatonic 7th chord for the root note of D Dorian (D) is comprised of D-F-A-C - a Minor 7th chord. Both the 3rd and the 7th are minor.
• The diatonic 7th chord for the root note of G Mixolydian (G) is comprised of G-B-D-F - a chord that includes a major 3rd and a minor 7th - creating a Dominant 7th chord (the default 7th chord when unqualified)

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So, one could say that A Aeolian is the C major scale with an emphasis on its 6th scale degree- Aeolian- known for being dark.

That's fair enough, but be cognizant of the fact that using C Major/Ionian mode as your reference point is based on the conventional western tonal system (as reflected in the piano keyboard - all white keys== C Major). Objectively speaking "all modes are created equal".

(As an aside, in modern jazz/pop parlance, the "default" minor scale is Dorian, not Aeolian. The m6 [F using A Aeolian] creates difficulties when building 'tasteful' chords and harmonies that are solved when using Dorian, which contains a M/Dorian 6th [B using D Dorian] - one might say Aeolian is a bit too dark.)

Answer 3

My comment got too long, so I'm posting as an answer. This is additional information to the excellent answers posted so far, and will likely not directly answer your question.

From what I've seen with the difficulty in understanding what the Modes are doing comes from some variance in terms, and different conceptualizations of tonic/scale/harmony relationships.

Some considerations:

Modes will sometimes be described in the sense of "pure" or "diatonic" modes, where you don't consider chromatic alteration when describing the mode. This uses the diatonic pattern established by the notes A through G, with half steps at B/C and E/F. In this description, setting one of the seven notes as a "Focus" note, or Tonic, creates in the listener the sense of a scale, with the whole-step/half-step pattern relative to that tonic. Thus, if C is the focus we hear Ionian or Major scale. With D as the focus we hear Dorian scale. The modes or scales may be chromatically modified when in use for a melody, especially with the modes that contain a minor 7th interval in the pattern, which may be raised to create a leading tone to the tonic.

Another way of using/describing the modes occurs when the mode is a description of changing the focus note or Tonic in an established scale. An example of this would be using Jazz Melodic Minor scale and re-focusing on one of the other scale degrees, changing the tonic but keeping the modified pattern of Melodic Minor. This creates a different scale than would be available using the "pure" mode patterns, and alters the corresponding harmonies available.

To add to the confusion, there is also a practice of teaching the modes as they relate to the Major scale only. This is an easy way to remember where the scale degrees in a mode are. The method is to learn the position of the Major Scale degrees (WWHWWWH) and then learn the mode by what changes from that pattern, usually using flat and sharp to describe the degree motion. For example, Dorian Mode may be described as Major Scale with a flat3 and flat7. This implies that modes are merely modifications of the Major scale, which isn't true, but is an easy way to remember them.

There is also some modal terms used in Jazz theory which can cause some confusion. For example the term "Lydian Dominant" is using Lydian to describe a Major Scale that has the 4th degree raised, as the Lydian mode would, and the term Dominant to indicate that the 7th degree is lowered as if you were using a Dominant chord. This terminology is used to describe the notes available or scale to use when improvising under a specific chord. That is to say, changing the scale to match the chord.

Answer 4

I think focusing on the collection of notes misses the essential fact:

Chords drive the expectations for a melody.

C-F-G-C has no relationship to Am-Dm-Em-Am but both point to the same collection of melody notes available (i.e. scales).

What is the resting target of the chord progression? A mode is just the collection of options the chords support as sounding correct. In a lot of jazz tunes the modes actually shift for 4-8 bar segments as the tune changes targeted "root" notes with temporary modulations to adajent keys or modes.