Jackendoff's Tripartite Theory

Ray Jackendoff has a book, Foundations of Language: Brain, Meaning, Grammar (2002). Read it.
Jackendoff is a linguist.
In it he proposes a tripartite theory of language with lexical, syntax and semantic systems.
These interact via interfaces.
He's got a lot of evidence that supports these different systems and it's nice to have a nice coherent theory.
He complains that the neural modellers (which I guess includes me) haven't solved the binding problem.
His tripartite theory considers neural processing, language learning, performance and competence.
I use this in my parser too.