Why is it difficult to explain language acquisition solely in terms of imitation and reinforcement?

In terms of child language acquisition ...

Chomskyan linguists argue that:

- Children learn language too easily. It should take them longer for the whole behaviourist learning process

- Children have innate knowledge of language

- Children produce incorrect utterances that they haven't heard anywhere before and so can't have imitated.

In terms of second language acquisition ...

- Learners make mistakes that are not grammatical in their first language either. Again, they can't have imitated this.

- Learners learn some things easily but some things, no amount of imitation and reinforcement will help them learn

Among other things...

No-one really believes in behaviourist learning theory anymore.