By far the most popular current conception of Universal Grammar (UG) is the one due to the generative linguist Noam Chomsky, whose theory of UG is supposed to be a theory of the human language faculty, i.e. a module of the mind/brain involved in the basic design of language. More specifically, he employs the term UG to refer to a system of principles and parameters that underlie all human languages (see Chomsky 1988 for a simple exposition). A major claim is that there are some highly abstract universal linguistic principles, such as the binding principles (named A, B, and C, respectively) determining what can or cannot be the antecedent of an anaphoric, pronominal, or fully referential nominal element. Other currently well-known principles include: subjacency, the Head Movement Constraint, the Empty Category Principle (see Cook 1988 and Chomsky and Lasnik 1993 for definitions and examples). These principles are good examples of formal universals, i.e. linguistic constraints of an abstract nature, as opposed to substantive universals, or linguistic primitives, which are best exemplified by grammatical categories like N(oun), V(erb), P(reposition), etc.