Mid-to late-20th century: generative linguistics and the search for universals.

In 1957, linguistics took a new turning. Noam Chomsky published a book called Syntactic Structures, this little book started a revolution in linguistics.

Chomsky trasformed linguistics from a relative discipline for interest mainly to PhD students (Doctor of Philosophy) and future missionaries into a major social science or direct relevance to psychologists, sociologists, anthropologists, philosophers and others. Chomsky has shifted attention waya from detailed descriptions of actual utterances, and started asking questions about the nature of the system which produces the output.

Chomsky points out that anyone who knows a language must have internalized a set of rules which specify the sequences permitted in their language. A linguist's task is to discover these rules, which constitute  the grammar of the language in question.

A grammar which consists of a set of statements or rules which specify wich sequences of a language are possible, and which impossible, is a generative grammar. A grammar will be a 'device which generates all the grammatical sequences of a language and none of the ungrammatical ones'.

Humans beings may well be pre-programmed with a basic knowledge of what languages in general are like, and how they work. Chomsky has given the label Universal Grammar (UG) to this inherited core, and he regards it as a major task of linguistics to specify what it consists of.