Originally Posted by: ovaltineWhy do we call it a flattened 7th if a chord is built on the 7th degree of the minor scale. Why not just call it a 7th chord?
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Because the major scale is the standard we start with, and the minor scale is a derived form, secondary to the major. And in the major the 7th scale degree is major (i.e. a half-step below the 1st):

A - 1st
G# - major 7th

So if we call it a "seventh chord" (written as vii; in Roman Numerals because we are identifying a chord and not just a scale degree note by itself), we would be referring to the major scale's 7th note. It would be a G# diminished chord. The 7th is already taken! :)

In order to uniquely identify the 7th note of the minor, we need to specify that it is the minor 7th scale degree note we are building a chord on (i.e. a whole-step below the 1st).

A - 1st
G - minor 7th

Add to this scale degrees should be referred to as major or minor depending upon which scale they are part of (major or minor). Whereas the chord progression degree which they are built upon are referred to as flat or sharp; and labelled with Roman Numerals to uniquely identify them or distinguish them from scale degrees.

Make sense?
[QUOTE=ovaltine]Are all chord progressions built on minor scale degrees referred to as flattened?

Only the ones that are built on the notes of the scale that are altered from the major scale and therefore unique to the minor scale.

Look at this list of all 12 possible chromatic scale degrees starting on A:

A - 1st
A# - flat 2nd
B - 2nd
C - minor 3rd
C# - major 3rd
D - 4th
D# - sharp 4th
E - 5th
F - minor 6th
F# - major 6th
G - minor 6th
G# - major 7th

You see that the 3rd, 6th and 7th can be major or minor.

Ergo, chords built on the major 3rd, major 6th and major 7th are not flatted chords and written as iii, vi, vii diminished.

Alternately, chords built on the minor 3rd, minor 6th and minor 7th are flatted chords and written as bIII, bVI and bVII.

In the case of the one that do not change, 1st, 4th and 5th, we only have to change the Roman Numeral from upper case to lower case because that identifies a major chord versus a minor chord:

A major (I)
D major (IV)
E major (V)

A minor (i)
D minor (iv)
E minor (v)

You are quite welcome for the help. Keep asking questions and thinking until you are confident you understand!