I'm afraid that despite reading a fair chunk of Mathemusicality I've given up on Westergaard's "An Introduction to Tonal Theory" in favor of Steven Laitz's "The Complete Musician". Steven Laitz is a Schenkerian but his book is fairly standard and uses harmony, voice leading and counterpoint.
Actually I'm beginning to conclude that if you want to compose, then starting off by learning music theory of any sort is totally wrongheaded. It is like trying to learn French by memorizing vocabulary and reading books on grammar (which is disturbingly how people try to learn languages in high school). The real way that people learn French is by starting off with very simple phrases and ideas then gradually expanding their knowledge by communicating with people who speak French. Grammar books and vocabulary books are important but as a supplement only to the actual learning that takes place from trying to communicate. Language and music are subconscious processes
I don't know what a similar approach to music composition would look like, but I'm reasonably convinced that it would be much better than the current system.
I should admit though that I am monolingual and I can't compose music - so my thoughts are based only on theory and anecdotes.
If I may ask, what was your issue with Westergaard?
(As a polyglot composer, I agree that there is an analogy of language proficiency to musical composition, but would draw a different conclusion: harmonic theory is like a phrasebook, whereas Westergaardian theory is like a grammar text. The former may seem more convenient for certain ad hoc purposes, but is hopelessly inferior for actually learning to speak the language.)
We recently established a successful Useful Concepts Repository. It got me thinking about all the useless or actively harmful concepts I had carried around for in some cases most of my life before seeing them for what they were. Then it occurred to me that I probably still have some poisonous concepts lurking in my mind, and I thought creating this thread might be one way to discover what they are.
I'll start us off with one simple example: The Bohr model of the atom as it is taught in school is a dangerous thing to keep in your head for too long. I graduated from high school believing that it was basically a correct physical representation of atoms. (And I went to a *good* high school.) Some may say that the Bohr model serves a useful role as a lie-to-children to bridge understanding to the true physics, but if so, why do so many adults still think atoms look like concentric circular orbits of electrons around a nucleus?
There's one hallmark of truly bad concepts: they actively work against correct induction. Thinking in terms of the Bohr model actively prevents you from understanding molecular bonding and, really, everything about how an atom can serve as a functional piece of a real thing like a protein or a diamond.
Bad concepts don't have to be scientific. Religion is held to be a pretty harmful concept around here. There are certain political theories which might qualify, except I expect that one man's harmful political concept is another man's core value system, so as usual we should probably stay away from politics. But I welcome input as fuzzy as common folk advice you receive that turned out to be really costly.