>> Chomsky would retort that "advancing the field" is meaningless unless it
allows us to "understand the field". But if natural language is a largely
arbitrary collection of rules in constant flux, there would be very little of
this "understanding" to be had.
Imagine a historian of the future reading reams of code written for all the
software we have in the modern era, in all the programming languages of the
modern era, from Java to Brainfuck and back. Would the historian of the future
be justified to conclude that there is nothing that connects these languages
with one another, that there is no common structure, nothing that can unify
them, "very little understanding to be hand"? If so the historian of the
future would be wrong, because all modern programming languages are designed
to run on the same substrate, modern digital computers. The existence of the
digital computer is the unifying characteristic that explains the existence of
any modern programming language.
In the same way, the variability of human language, internal or external, is
without any shadow of a doubt explained by some processes in the human mind.
These processes may be too complex to understand, perhaps, but understanding
them is a worthy scientific goal. And there is, indeed, much "understanding"
to be hand in that direction.