I have read three Chomsky books–although none specifically on his linguistic topics-- and I had a feeling that I was right that his thoughts are that we do hold innate knowledge…
" Noam Chomsky has taken this problem as a philosophical framework for the scientific enquiry into innatism. His linguistic theory, which derives from 18th century classical-liberal thinkers such as Wilhelm von Humboldt and René Descartes, attempts to explain in cognitive terms how we can develop knowledge of systems which are too rich and complex to be derived from our environment. One such example is our linguistic faculty. Our linguistic systems contain a systemic complexity which could not be empirically derived. The environment is too variable and indeterminate, according to Chomsky, to explain the extraordinary ability to learn complex concepts possessed by very young children. It follows that humans must be born with a universal innate grammar, which is determinate and has a highly organized directive component, and enables the language learner to ascertain and categorize language heard into a system. Noam Chomsky cites as evidence for this theory the apparent invariability of human languages at a fundamental level. In this way, linguistics has provided a window into the human mind, and has established scientifically theories of innateness which were previously merely speculative.
One implication of Noam Chomsky’s innatism is that at least a part of human knowledge consists in cognitive predispositions, which are triggered and developed by the environment, but not determined by it. Parallels can then be drawn, on a purely speculative level, between our moral faculties and language, as has been done by sociobiologists such as E. O. Wilson and evolutionary psychologists such as Steven Pinker. The relative consistency of fundamental notions of morality across cultures seems to produce convincing evidence for the these theories. In psychology, notions of archetypes such as those developed by Carl Jung, suggest determinate identity perceptions."
en.wikipedia.org/wiki/Innatism
So, my understanding is that he is saying we hold the basic knowledge of grammar, but still need the external environment to trigger it; but we none the less hold the knowledge…