Why does this chord progression sound good even though it's using notes not in the correct key?

[Richard Lindsey]

@MixBass I think part of your confusion stems from not using major(ionian) scale as standard rule against which all intervals and scales must be compared. The answer to "raised/lowered with respect to what" should almost always be the major scale.

If you learned Dorian as a modified minor scale, it may seem logical to say the "6th is raised"
If you view Dorian as a modified major scale, you see the see a minor 7th and a minor 3rd.

In fact, I always compare scales (and intervals and chord tones) to the major scale, as I am sure many others do.
It gives a nice shorthand for memorizing:

Major 1 2 3 4 5 6 7
Mixolydian 1 2 3 4 5 6 b7
Dorian 1 2 b3 4 5 6 b7
etc...

I do the same thing; it's just how many of us were taught. In the major scale, all the intervals *from the root* are either major or perfect; in all the other scales, one or more intervals from the root must be minor, augmented, or diminished.

 

[MixBass]

Apologies to the OP for the derailment.
Too many things to respond to but again, I understand the
nomenclature. A half step below an octave is a Maj7 and a whole a minor. My observation is: for students who haven’t been to music school as many students are, I can achieve the desired result sooner with terminology lowered or raised. Dorian: minor scale raised 6 instead of minor scale Major 6. Until one ventures into exotic scales, bebop scales etc...a fixed interval, a whole step above a perfect 5th for example, a Maj6th, I continue to feel is less confusing for an average student ( not college SATB studies for ex) as a raised 6th.
The always controversial mode discussion haha, I love them but am intrigued by how many different ways people think of them.
My favorite use is simply to recognize the sound as quick as possible. So what, Uptown funk, Good times for example sound Dorian. Minor with a “raised”, ok Maj6.
Pretty woman, Birthday (Beatles) sound Mixolydian. Major with a “lowered”, ok minor 7.
I don’t think of D Dorian as a parallel mode to anything. I think of it as D Dorian. Dorian architecture starting on D. On the other hand, notating A Dorian for example I would say is easier to think of quickly as key sig of G for sure.
And as stated by someone earlier, notation is the surest way to achieve an exact result. (I love polychords and clusters but a bit dodgy if named rather than notated IME).

 

[Wasnex]

Apologies to the OP for the derailment.
Too many things to respond to but again, I understand the
nomenclature. A half step below an octave is a Maj7 and a whole a minor. My observation is: for students who haven’t been to music school as many students are, I can achieve the desired result sooner with terminology lowered or raised. Dorian: minor scale raised 6 instead of minor scale Major 6. Until one ventures into exotic scales, bebop scales etc...a fixed interval, a whole step above a perfect 5th for example, a Maj6th, I continue to feel is less confusing for an average student ( not college SATB studies for ex) as a raised 6th.
The always controversial mode discussion haha, I love them but am intrigued by how many different ways people think of them.
My favorite use is simply to recognize the sound as quick as possible. So what, Uptown funk, Good times for example sound Dorian. Minor with a “raised”, ok Maj6.
Pretty woman, Birthday (Beatles) sound Mixolydian. Major with a “lowered”, ok minor 7.
I don’t think of D Dorian as a parallel mode to anything. I think of it as D Dorian. Dorian architecture starting on D. On the other hand, notating A Dorian for example I would say is easier to think of quickly as key sig of G for sure.
And as stated by someone earlier, notation is the surest way to achieve an exact result. (I love polychords and clusters but a bit dodgy if named rather than notated IME).

I guess your approach is okay if the student will never progress beyond a rudimentary understanding.

However if they will continue to study theory, you should teach them to correct way from the beginning. IMHO it's not really that much harder and it avoids a lot of confusion down the road. The problem is how do you know if someone will progress or not?

 

[BassChuck]

The sound is in your ear.
'Key' is just a mental organization to help understand the sound.
If the key doesn't match up with the sound, perhaps your understanding of 'key' should be examined.