I posed the same question to Chomsky and he was generous enough to answer my question.
My question was:
Dear Sir,
I'm Ramachandra Reddy, from the southern state of Andhrapradesh; India. I'm a research scholar at Dravidian University. I'm researching on Universal Grammar proposed and propagated by you. I'm very much fascinated by the name "Noam Chomsky" as it is associated with unparalleled intellectual abilities and the courage to question the authority. These qualities inspired me to carryout research on Universal Grammar.
Research in Universal Grammar is really challenging and moreover it is an evolving topic. There is lot of room for more research in the area. Unfortunately I don’t have the guidance of a capable teacher on this complex topic. So I’m doing it on my own and I seek a little bit of help from none other than the pioneer. I might be a bit overambitious in my desire but I firmly believe that you are generous enough to help this student. Moreover there is something common in between both of us. That is, the legacy of Panini. You are a great admirer of Panini, the ancient Sanskrit scholar who wrote the book Asthadhyayi in which he proposed the recursive theory, which I think, formed the basis of your generative Grammar. So I’m a student from the country of Panini.
As part of UG you proposed that there is something called LAD (Language Acquisition Device) to make up for poverty of stimulus. There is another theory called critical period theory which contends that LAD is not available beyond 6 or 7 years and as a result, grown up students and adults find it difficult to learn a second language. Now I would like to know from you whether the critical period theory is right, and if it is not true, obviously the LAD should be available to even the adults and if it is available to them in what way do they derive benefit out of it in learning a second language?
Looking forward to your reply
With regards
V. Ramachandra Reddy
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To the above question Chomsky answered by saying:
Glad to hear of your interests and concerns. There are, incidentally, many outstanding linguists in India with whom you can discuss these matters. In Hyderabad for example, not too far away.
It is generally assumed that there are several "critical periods," one about 6-7 and another, more significant one, around puberty. There is evidence that ability to acquire language weakens for most people after these critical periods of maturation are past, though there is individual variation. It is an open research question whether past these periods language learners are still using some weaker version of UG, or are relying on the languages they have learned already. Probably both. But there are no simple answers. These are hard questions that require more investigation.
There are lots of reasons why one should want to learn a second (or third, or fourth,....) language, which opens up new worlds for the learner.
Noam Chomsky