This approach suffers from certain drawbacks which were first highlighted in the 1960s by Noam Chomsky, who has also been responsible for a further fundamental shift in linguistic research in the latter half of this century. Chomsky pointed out that no matter how large a language corpus is, it will never contain examples of every conceivable kind of linguistic construction. Rather than pursue this futile aim, attention has shifted towards unearthing the principles of the linguistic system which underlie the actual sentences being analysed. In this way, due consideration is given to the fact that a finite system of grammatical rules can generate an infinite number of novel sentences. This shift of emphasis allowed large bodies of data to be supplemented by the spontaneous grammatical intuitions of native speakers about what is, and is not, grammatically permissible in a language.
Linguists often rely on their own intuitions, or alternatively, make use of an informant.
In either case, it is important that intuitions provide a reliable source of information, and fortunately, this is indeed the case in the majority of cases. Intuitions are not infallible, though, since there are many occasions when linguists disagree. Nevertheless, the restoration of linguistic intuitions as an acceptable form of data reveals the importance of tapping the underlying mental system which gives rise to language behaviour. As a result, the last four decades have witnessed a radical reassessment of the goals of linguistic theory. The analysis of language as an abstract object, in and of itself, has given way to the task of characterizing the knowledge of language as it exists in the minds of native speakers.