What is the correct Roman numeral notation for use in modal pieces?

Question

Looking at a lead sheet (Scarborough Fair), it is noted that the key signature is D major. On closer inspection the song appears to be in Dorian mode. I am guessing that the better approach when e.g. referencing the chords in this case, by Roman numerals would be to refer to them as per the key signature, that is to say the V chord ‘A’ does not become a IV chord, or the I ‘D’ chord become the VII simply because it is in Dorian mode, as this would be too confusing.

I shall be glad for any clarification here.

Many thanks.

Since writing the above, and reading the helpful information I found this link, which may be of interest to anyone, who like me may be unclear about what a tonic is in terms of modal scales.

What is the tonic of a musical mode?

Answer 1

Roman-numeral notation is relatively standard, and to determine any given Roman numeral you need two things:

1. The scale degree of the root of the chord. (This demands knowing what tonic is.)
2. The quality of that chord.

Thus it doesn't matter what mode you're in, only what tonic is. If you're in E Dorian, E is tonic, and therefore an A chord is built on scale-degree 4. If that A chord is major, then this is a IV chord. But the B-minor chord, built on scale-degree 5, would just be v. A D-major chord, built on scale-degree 7, would be ♭VII, and so on.

Answer 2

The key signature here seems to be a red herring - and inaccurate. If the tonic is indeed D, then it may well be that the key sig. ought to be that of the parent key - C (No ♯/♭). And that doesn't dictate the tonic is C. The tonic is the note/chord where a piece appears to be at rest, at home. So, in this case, D.

Dorian is a minor key (with m3), so tonic is designated 'i'. Therefore here, Dm=i. The dominant chord in Dorian is alsominor, so will be 'v', not 'V'. Here - Am.

But we need to be careful whether you're saying the mode is D Dorian or it's the Dorian of D. Difference.

Answer 3

You can use them exactly how you would use them in a major or a minor key. Your starting point (degree 1) is going to be different and will be the tonic of your mode. Aside from that, the only things that change are the numerals' case and the application of diminished or augmentations marks where appropriate.

So, if you're doing 1, 2, 5, 1 in Lydian for example:

F Lydian: I, II, V, I Fmaj, Gmaj, Cmaj, Fmaj

All major chords because we are modifying the degrees to fit C Major (parent scale.)

So the progression in major would be your standard:

I, ii, V, I

And Lydian, using F as your starting point, as your degree 1:

I, II, V, I

Dorian, with D as the starting point:

i, ii, v, i

etc...

Answer 4

it is noted that the key signature is D major

If you mean the song by Simon and Garfunkel the signature of D major would be 2 sharps (F#,C#) and it must be in E-dorian, and the C# would be the major 6th of dorian. That means we have a major IV (A) like Richard says.

Most images (sheet music) I found are in minor (looking like aeolian) with an additional accidental (major 6th!) what indicates that this must be dorian.

You'll find searching by images two different versions in d, one has the signature of of C-major => d dorian, another 1 flat=> d-minor (aeolian)

The following version (s. image) must be identical with yours (additional accidental=C#)

This one is notated in E-aeolian - compared with yours - it has only 1 sharp in signature and an additional sharp (C#) as an accidental. So don't mind so much the mode as the final chord will be the tonic (and here obvious the 1st note too!)

So Em = i, D=VII, A=IV, G=III

The problem has been discussed already here in Dorian of G (G-dorian) but we miss the signature of 1 sharp so it looks like aeolian of C (a-aeolian) with additional F#:

Analysis of Scarborough Fair

Read what Scott Wallace has written in his answer:

A short answer: Scarborough Fair is not in the minor, but is modal: Dorian (that's where the major IV chord comes from) and Aeolian (the minor iv). The modal character is underscored by the progression VII-i, which is normal for Dorian and Aeolian, and the fact that there is no major V chord.