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Many of I-V-vi-IV chord progression examples are C major. My question is Minor. For example of Am key signature, the 1564 is Am , Em, F, Dm; however, I-V-vi-IV should mean major-major-minor-major. May I have your help on this?

3 Answers 3

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I think you need some explanation of what the Roman numerals actually represent.

First, the Roman numerals represent the tones of a key signature which are used for the roots of chords. No chord qualities like major, minor, diminished are represented at that level.

Secondly, in some Roman numeral analysis (RNA), upper/lower case, along with symbols o and ø is used to show major/minor/diminished quality.

Not all RNA systems use upper/lower case and are only concerned with identifying the scale degrees of chord roots. So, in that kind of system you get...

Roman numeral - Scale degree
I             - Tonic
II            - Supertonic
III           - Mediant
IV            - Subdominant
V             - Dominant
VI            - Submediant
VII           - Leading Tone (or Subtonic of minor key signatures)

At this point the important thing is those seven Roman numerals will apply to both major and minor key signatures, because that simple system does not use upper/lower case to distinguish chord qualities. (A well know text that uses this system is Walter Piston's Harmony - at least the first edition, not sure about later editions.)

If we use that system to write out the progression, it would simply be...

I V VI IV

...which in plain English would mean...

tonic triad, dominant triad, submediant triad, subdominant triad

...in either a major or minor key.

With that understanding, let's use upper/lower case to indicate chord quality. We will start with major keys, because that is simplest...

I V vi IV

...which would read something like...

tonic major triad, dominant major triad, submediant minor triad, subdominant major triad

When you get to minor keys things become a little complicated, because the sixth scale degree (the submediant) and the seventh scale degree (the leading tone) are often raised a half step from the key signature. (Read up on minor key harmony, it's too complicated to go into here.)

Theoretically, the various forms of the sixth and seventh scale degree in minor result in a large number of possible Roman numeral chord symbols in minor keys, but if we keep things simple and realize that I V VI IV forgoes a cadential progression, we can say the VI and IV chords will simply be diatonic chords of the key signature, and using letter case, they will be VI and iv. Of course the tonic triad will be minor in a minor key, so that will be i. That leaves only the dominant triad to be considered. If you want to sound of the proper major/minor harmonic system, the dominant triad will be a major chord, and so that would be V. But, if you want a more "modal" sound, the plain diatonic sound of aeolian mode, you could use the minor dominant triad of the unaltered key signature, which would be lower case v. So, by this reconning, you have to basic possibilities for the progression in minor...

Am: i V VI iv Am: i v VI iv

Keep in mind there are other ways this kind of chromatic inflection can happen beside minor key music. The most common is borrowed chord harmony. A really common example is using a minor subdominant in a major key...

C: I V I iv | I...

The take-aways are then...

Roman numerals first represent the scale degrees of the key signature The sixth and seventh scale degrees vary in minor key harmony Borrowed chord introduce alterations from the key signature You need to decide how to chromatically "inflect" chords in a progression Select letter case and other symbols in RNA to represent chord qualities after deciding how various tones are chromatically inflected.

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  • Personally, I've never used only or seen only RN capitals, ever. Caps for major, lower case (i, ii) for minor, etc). Perhaps I've lead a sheltered life, so I'm off to search!
    – Tim
    Jan 10 at 8:26
  • @Tim, I've seen it in older theory book. A seminal example is Piston's Harmony. My point is to first associate the RN with a scale degree and secondly with a chord quality. Jan 10 at 16:07
  • FWIW, I checked my 1987 Harmony, 5th Edition by Piston (& Mark DeVoto since Piston died in 1976) and it still uses all caps RN. (Maybe you're supposed to SHOUT THE CHORDS?)
    – Theodore
    Jan 10 at 21:05
  • @Theodore, interesting, I wasn't sure about later editions. My copy is a first edition. Jan 10 at 21:07
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True that in major I V vi IV is maj. maj., min., maj. But why on Earth should that pattern be carried across to minor? i doesn't equal I, iv doesn't equal IV, etc.

i v VI iv is what it is, there's no direct musical correlation, just the numbers are the same (in Arabic, not RN!)

The sound isn't the same, the intervals between the chords are the same, but that doesn't mean their sound will be the same - after all, major and minor chords will always be different. What did you expect?

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  • Thanks for your reply. Does it mean I-V-iv-VI is only for major key signatures?
    – SBMVNO
    Jan 3 at 11:29
  • Since I is the root, and represents the key involved, then, yes!
    – Tim
    Jan 3 at 11:51
  • It could also be i V VI iv (or even i V VI IV given the right melody) and still be a minor version of "1-5-6-4".
    – Theodore
    Jan 3 at 16:25
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I'm not sure I understand your question but each mode technically has only certain notes at its disposal. At least when you follow rules such as those in partimenti.

So a I chord in Ionian mode (major scale) key of C would be CEG and a IV chord would be FAC. Both are major.

In C aeolian mode (natural minor) the notes are 12 b3 45 b6 b7 8 which means your i and iv chords are now minor. C Eb G and F Ab C.

Each mode changes some note degree and if you obey the regole or rules, it will yield a different harmonic landscape. So if you played C dorian the notes are 12 b3 456 b7 8. The most important note in Dorian is the natural sixth. That means your i is obviously minor but your IV is now major giving the Dorian mode a happier sad than the two minor chords in aeolian. To hear the difference play these chords I IV I, then i iv i, then i IV i. But the sixth is not the only important note. Each mode changes where the half step notes are and that has huge harmonic differences, too.

All the modes are like this. It is also why the early church used modes for different emotions.

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