According to Pinker, language is an instinct: "an ability that is uncontroversially present in every one of us". He justifies this by claiming that it is logically impossible for a child to acquire a linguistic competence of this complexity through the kind of exposure to language that children receives in their home environment. Yet what are the characteristics of an instinct? Can a second language be learnt in an instinctual manner?.
First of all an instinct is a biologically constrained process with a specific timetable ending at puberty and that is characterized by its uniformity in spite of considerable environment variation, as in the ways parents talk to children. Second, the instinct of language is a proficiency that exists inherently, innately inside of each one of us, as walking or breathing in spite of the existence sometimes of certain deficits like an handicap. Finally, Pinker stresses on the fact that language as other instincts is not taught to children "a preschooler tacit knowledge of grammar is more sophisticated than the thickest style manual" and this doesn't need any triggering events. As long as a child is exposed to a threshold amount of linguistic during the critical period, he will uniformly acquire language. Yet, all of that we have discussed above applies to first language acquisition; then, what about second language acquisition? To answer this question we will try to analyze as accurately as possible the case of two immigrants Arash and Mircea that have arrived to the states. .
Arash is 23 years old, Iranian refugee who was not exposed to the English language in a consistent way, he has learnt a little bit at school but has forgotten it and he's restarting from scratch at the age of 23. Therefore, English language in the case of Arash has neither developed in a uniform manner nor has developed during the critical period. Moreover, it seems from the context that he is hardworking and that he is investing arduous effort in learning and this contradicts instinct nature since instinct emerges unconsciously, automatically, without any effort.