Jack.

If you read further back you will note a request from Geoff the duck for an explanation of modes.

This I gave, but first gave an explanation of basic chord theory so that they could be put in some sort of context and have some kind of meaning.

A also clarified that the modes that he was referring to were the modes of the major scale.

When I first encountered modes I was put off by the fact that there were so many of them and I didn't have any idea how to use them or why I might want to.

In hindsight, I am able to say that I used to enjoy the sound of the Major scale, the Mixolydian, the harmonic minor, the Dorian and the Aeolian.

However, when i composed music, it tended to remain in one key as i didn't know how to modulate smoothly.

Before you comment further, yes I know that in most folk this isn't an issue.

However, when I heard a song with the chords D, Am, C, G, although I could hear that I needed to use a major chord with a flat 7 to improvise over it, I did not know that this was because the piece was modal, much less that it was in D Mixolydian.

It wasn't until I learned a bit of chord theory that the concept of the modes began to make sense.

As for this comment ...

"when the jazz theorist insists that their range of harmonic options is ineluctably dictated by the laws of acoustics and works equally well for any tune whatever, they're talking bollocks."

If I ever encounter anyone who is doing something of this nature I'll be sure and tell him your point of view.

In case you hadn't noticed, my reason for explaining what are the most rudimentary basics of western music theory was that Geoff reminded us that not everyone knows what it is. since then, at least two people on this thread have found it interesting enough to go away and experiment with.

In the meantime, your analysis of folk forms etc in which you mention ...
"isolated bass notes; octaves; fifths; major and minor triads; and dom7 chords (only at final cadences). No diminished, maj7th, 9th, 11th or 13th chords."
... is an analyisis made using terms and concepts taken straight out of western chord theory.

The whole idea of intervals of any sort, let alone Major and minor 3rds etc is at the heart of the evolution of western music. It is from the study of intervals during medieval and rennaissance times that western chord theory was developed.

Western chord theory was first defined during the Baroque era and is not just some Jazzers wet dream as you appear to be implying.

The first person to define chord theory as we know it today was Rameau in his "Traite d'Harmonie" in 1722.

It is not a series of rules, but a series of observations as a result of which our understanding of harmony was able to evolve further and faster.

Why you should have a problem with me taking the time and effort to explain it in brief when asked to do so is beyond me.