By divorcing linguistics from the inductive discovery procedures and directing it towards explanatory adequacy, Chomsky triggered a very intensive development of linguistic theory. Since the appearance of Syntactic Structures (Chomsky 1957) the major task of students of language has been the search for linguistic descriptions which satisfy conditions of explanatory adequacy. For some time, the scope of these descriptions was strictly limited—they accounted for the linguistic competence of an ideal speaker. Subsequently, the attitude changed. At present, the field of linguistic research is approached by a multitude of models which differ with regard to (a) the kinds of facts they account for, (b) the goals that these accounts are to achieve and (c) the range of means employed in the pursuit of these goals in relation to the relevant facts (Moravcsik 1980). While some models are models of linguistic competence, others are models of linguistic performance and take into consideration psycholinguistic and sociolinguistic evidence. Whereas certain models strive to cover representative bodies of data, others work within limited domains of language, on the assumption that one creates grammar through constructing fragments. Most models, following tradition, stick to phonology, morphology, syntax, and semantics; there are some, however—actually an increasing number of them—which deal with communicative sentence perspective and pragmatic issues. Problems which until not so long ago were falling strictly within the realm of applied linguistics are thus getting legitimately established as issues of (theoretical and descriptive) "pure" science of language.