I'm a guy who likes abstract stuff, and that definition seems extraordinarily abstract to me, to the point of obfuscating the actual meaning of what we're talking about. Am I right that seems that the definition of grammar there is an almost-meta abstraction of structure?
I still can't help but believe that, in practice the 'less radical' points I mentioned, like tense, mood and case (which I think would be switches, right?) arise differently in different contexts, if at all, owing to differences in cognition in various groups, and thus reinforces that mode of cognition in someone who learns the language.
The difference in morphology between, say, Ancient Greek and Modern English is pretty drastic, so what gives? In fact, I don't think English has ever been as morphologically-complex as Ancient Greek, and yet some hypothesize that they even descended from the same Indo-European language...if both languages start out from the same point, but evolve with a completely-different grammatical structure that makes different concepts explicit or notable, why would that happen in light of a true universal grammar that is inherent to everyone?
It's one thing to say that everyone at a certain intellectual level have a capacity to understand and use certain grammatical constructs, but to claim them as inherent to all people seems sketchy...
>The theory is that the principles of universal grammar arise directly from the structure of the brain, while the parameters are set during language acquisition.
Wouldn't that prove that language inherently affects cognition, and thus proves linguistic relativism? I don't think you actually made a point in favor of linguistic relativism, but that was the theme of this whole discussion thread.