A distinctive feature of the Linguistics Program at MIT has been its insistence on explicit theories of language formalized as grammatical rules and constraints. The concern for explicitness facilitates the comparison and evaluation of alternative models. Only after extensive parts of the grammars of different languages have been formulated is it sensible to ask questions concerning the ways in which languages differ—or the ways in which all languages are the same. Consequently, a large part of our effort is devoted to the study of linguistic detail (for example, the interpretation of English verb phrase ellipsis, the morpho-semantics of the Greek perfect, the syntax of multiple questions, prosodic phrasing in Korean, or the articulation of reduced vowels in English).

We focus on phenomena that we believe will provide rich insights into the nature of language. Their discovery requires effort and persistence, and a certain measure of good luck. Our program has been noted for its psychological interpretation of linguistic theory. This view holds that humans have an innate language faculty in which the universal principles of human language are grounded.

In learning their native language, children acquire specific rules that interact in complex ways; the entire system is learned rapidly and with little effort. The success of human language learners suggests that they rely on a highly restrictive set of principles that does not require (or permit) them to consider many alternatives in the analysis of a particular construction.

Since there is no evidence that the underlying principles that define the class of possible rules and grammatical systems are learned, it is thought that these principles serve as the preconditions for language learning, forming part of the innate capacity of every normal child. Viewed in this light, the principles we are attempting to discover constitute part of the genetic endowment of all humans.