This is from a previous post I did on theory. It has some infomation & ideas that might be helpful to this discussion.

The first people that really understood music in the conceptual sense were the ancient Greeks. Back when they were the first humans to build conceptual knowledge in an organized, systematic manner (back when they were discovering the basic principles of math, biology, science, philosophy - all that good stuff!).

We, of course, don't know exactly how their music sounded (no existing records - written ... or recorded!). But that is no matter. We do know the important parts. They started with the science of physics (the acoustic nature of sound) pitch-specific tones ("pure tones") and then they organized them in a way that is consistent with human hearing and thought. The basics of their diatonic scales and modes have changed a bit since 3000 years ago. But the fundamental ideas and approach are still the foundation of what we use to the present day. Not bad for a bunch of ancient old timers.

Unfortunately, even some of those old timers tried to incorporate some ridiculous, irrational ideas into the newly emerging science of sound and music. Pythagoras, in particular created a bizarre combination of loony mysticism and reality orientated math that resulted in an early form of numerology. Later this was picked up by Johannes Kepler who tried to incorporate geometry, astrology and music in his Musica Universalis (Music of the Spheres).

Then, there are the church modes of the Catholic Gregorian chants, in which the church tries to conceptualize music to fit it's "sacred needs". To be fair, they did organize the modes according to some scientific methods and principles. But also introduced the idea of "wrong notes" and "wrong orders" and in general "wrong ways to do things in music".

Even in the more enlighted Enlightment, we find theorists that are tainting their reality oriented observations with unnecessary, counter-productive addendums.

So, we wind up with a history of music theory that contains some crucial, invaluable information and systems of thought based on reality and proper conceptualiztion. But it is also intertwined with some irrational notions and contradictory ideas.

It is a self-appointed task of mine to rid music theory of the nonsense! :)

The purpose of any theory is to conceptually identify and organize perceptual data. If the theory is not based on any perceptual data it is mere speculation. Theory is not something "disconnected" from reality. I realize there are some people that claim this is true. They are wrong. If a theory (or some part of it) is contradicted by perceptual data (i.e. reality), then the theory is wrong to that degree and needs to be modified.

When you hear, "It works in theory, but not in practice", what that means is, "I have a flawed theory, but I am unwilling to alter it so that it properly matches the facts of reality."

So, music theory is how we mentally identify and organize the perceptual data (the sound) of music. Music is, in a sense, the science of sounds organized in a very specific manner.

We are only interested in what is possible in physics (via the science of acoustics - the nature of sound) and what is valuable to humans (via the nature of hearing and thinking - conceptualization).

It is also important to distinguish between science and convention.

Ever since the classical theorist started calling certain things "wrong" or "improper", there was sure to be a reaction the opposite direction. This eventually resulted in some other group (and eventually "rock and rollers") talking about "breaking the rules".

So, you get the classical theorists suggesting that it is wrong to play certain notes in certain order. And then you get the reactionaries who claim to be "rebellous" because they are "rebelling" against the classical theorists. Which would be funny if not for the tragic fact that the reactionaries also wanted to throw out the science along with the stupid rules the classical theorists superimposed upon the science.

Again, music theory can tell you what the notes, scales, chords are. It can even help you organize and understand huge systems of notes, scales and chords. It can tell you that you are wrong if you want to call a major scale something other than what it actually is. It can tell you that you are wrong if you want to call a iii-I chord progression a resolution instead of a V-I.

But it can't tell you that you have to play a major scale. It can't tell you that you have to play a certain chord progression. It can't tell you that you must use a proper resolution. That is not its function.

In this way music theory is like the principle of mathematical addition. There are rules about numbers and how to add them. Once you pick two numbers to add together, then you get a certain, specific sum. This is like music theory. But the rules do not and cannot tell you which numbers to add together. That is up to you decide.