What is the actual claim being made here? It’s pretty obvious that if you take the union of all languages’ grammar, you get some kind of giant grammar. That’s not interesting. And it’s clear that related languages are likely to have related grammar, so that’s not interesting. And it’s clear that subject and predicate have to be listed in some order, maybe with a verb. It’s not interesting.

So what is this universal grammar supposed to be? The language of God? Is this a religious quest thing?