# The ambiguity of certain chord qualities in Roman numeral Analysis

Roman numeral analysis uses capitalization to disambiguate Major from minor, so the paradigm is not entirely based on inference. There seems to be a double standard as to what is explicit and what isn't. The most prominent example is the lack of distinction between a Major 7th chord and a dominant 7th chord.

Notice how the two Roman numerals circled in red look like they might represent the same quality:

• Both Roman numerals are capitalized
• The figured bass suggests the same inversion

However, they are both representing different qualities. There is no quality symbol suffix (Δ, Maj, or Dom) to disambiguate them. This is especially confusing, because this syntax clashes with the syntax of jazz/pop chord analysis. "X" (the alphabetic root of the chord) immediately followed by 7 signifies a dominant chord quality in jazz/pop chord analysis (see the chord symbol underlined in yellow).

Additionally, using the syntax above, you'd have to contextually think about the scale degree of the chord in order to inference the quality of 7th chord you are dealing with, which presents added hurdles for both beginners and modern learners versed in jazz/pop syntax.

Why not explicitly include quality symbol suffixes for seventh chords (such as -, Δ, Maj, Dom, etc.) like in the manner below?

Common practice composers didn't consider dominant seventh chords to be stable entities, which is a large reason for the lack of disambiguation. In music of that era, V7/IV is a more functionally appropriate way to describe a dominant 7th chord built on the first scale degree. But in the modern age, in the music of Gershwin, Ravel, or jazz and blues in general, the I7 can function as an entirely stable entity, devoid of any secondary function at all. Hence, I think Roman Numeral analysis should take some cues from jazz chord analysis and become a bit more explicit.

The two systems are intended to describe different things: Roman numerals are interpretive (and designed to describe common-practice period major/minor tonality); Chord notation is intended to be practice, and doesn't necessary reflect the harmonic role of the chord.

The Roman numeral system is intended to give the contextual roll of the chord. So it's a given, when one is sufficiently familiar with the system, that I7 is a major seventh chord, V7 is a dominant seventh chord, and ii7 is a minor seventh chord (in a major key). A I chord with a minor seventh would not be labeled as a I chord; most likely it would be V7 relative to the fourth degree of the scale (that is, in the key of C, a Ib7 chord would actually be V7 of F).

The jazz/pop chord notation is intended to be practical, thus the qualities of seventh chords are made explicit in the notation. "Even worse" jazz and pop don't necessarily follow the roles assigned to various Roman numerals. For example, the I chord is a blues is typically a dominant seventh chord. This runs counter to the system of major/minor tonality that Roman numeral analysis is intended to describe.

Conclusion

The ambiguity described is relative. Chord notation is highly ambiguous if one wants to look at harmonic interpretation; Roman numerals are "ambiguous" in the way described if the goal is practical realization of the harmony.

• Thanks for the explanation. On account of the fact that the I7 in the common practice functions as a secondary dominant, it makes sense that there is no symbol reserved for it. But obviously, a I7 chord in the music of Gershwin is a perfectly stable entity. I guess the symbols detail the usages found in the common practice era, which are slightly outdated. Another thing to ponder is why anyone would go so to far to capitalize anything if everything is contextual? Is there a strong need to symbolically disambiguate the capital I from the lowercase ii if the context is known to be major? – Nakul Tiruviluamala Feb 27 at 22:51
• I think more explicitness might be a good thing to adopt into the system going forward. Just as we want to disambiguate the IV from the iv in modal mixture scenarios in the music of Bach, we'd probably want to disambiguate the I7 from the IMaj7 in the music of Gershwin. – Nakul Tiruviluamala Feb 27 at 22:54
• @NakulTiruviluamala It depends on one's intention. IMaj7 is considered consonant in the music of Gershwin, but dissonant in the music of Bach, Mozart, or Beethoven, for whose music the Roman numeral system was devised. It's the same core issue as I7 being a tonic chord in blues but not in classical music. – Aaron Feb 27 at 22:58

Extensions are based on figured bass, and therefore relate to the diatonic scale. V7 isn't a major minor-seventh just because that's the most common seventh chord, it's a major minor-seventh because if you climb the major scale in thirds from the fifth degree, that's the chord you get; in contrast to I7, which, containing the seventh scale degree, is a major seventh. We don't tend to adopt jazz-like notation (e.g., I♭7), even though modified intervals exist in figured bass, for much the same reason we tend to refer to III as V/vi -- we're not just talking about chords when we use roman numerals, we're talking about chords in relation to other chords.

We use upper/lowercase (alongside modifiers for diminished and augmented) because altering specific scale degrees/borrowing chords from the parallel key is extremely common and needs to be accounted for. I guess you could view minor-key V as being shorthand for V/I if you really wanted, though it puts you in the weird position of recursively viewing minor-key I (as in, a Picardy third) as I/I, and doesn't accurately convey the fact that V is just an ordinary part of minor tonality with a distinct function from v.

This system is a little limited (though less limited than you seem to think), but it exists primarily to describe music which broadly conforms to these limitations.

Consider that RN basically has any note in a chord - especially four-note chords - as a diatonic note. So 'stacking thirds' will automatically result in I7 being a major 7th, and V7 a dominant.

To differentiate, 'I dominant seventh' will be labelled V7/IV - the dominant seventh of the four chord - or a C7 dominant chord of F. That way, there's no confusion.

• Why does roman numeral analysis use capitalization to disambiguate Major from minor if everything is purely based on inference? I'm pointing out that there seems to be a double standard as to what is explicit and what isn't. In the common practice, it is indeed correct that the I7 functions as the V7/IV. But in the modern age, in the music of Gershwin, Ravel, or jazz&blues in general, the I7 can also be an entirely stable entity on its own accord, and not serve a secondary function at all. Hence, I think RNA should take some cues from jazz chord analysis and become a bit more explicit. – Nakul Tiruviluamala Mar 1 at 6:26