‘X-bar syntax, as a theory of phrase structure grammar, makes a significant contribution to both the descriptive and the explanatory adequacy of Linguistic Theory.’ The aim of a theory of language is to describe a speaker’s linguistic competence. (Class notes) In order for a grammar to be satisfactory it must satisfy two main conditions: descriptive adequacy and explanatory adequacy. A grammar that satisfies descriptive adequacy “describes the grammatical sentences of a language in such a way as to uncover deeper principles and rules, which capture in a more satisfactory way the intuitions of the native speaker. A grammar which is formulated in accordance with the principles and conventions of a general i.e., universal linguistic theory with explanatory power is said to meet with explanatory adequacy.” (Class notes)During the first half of the term, we were introduced to a theory of phrase structure grammar (PSG) which includes two levels of categories: word-level (N, V, A, P, etc.) and phrase-level (NP, AP, VP, PP, etc.). However, this is not a satisfactory method of classification because it does not include a description for a string of words that is neither a full phrase nor a word; therefore failing to satisfy descriptive adequacy. Furthermore, it does not satisfy the condition of explanatory adequacy because it does not enable us to state general principles that are valid across different grammatical categories within a language, i.e. category neutral. Moreover, a grammar with two levels of categories is not powerful enough to state principles that hold true universally. In this essay, I will demonstrate how the X-bar theory of phrase structure grammar contributes significantly to both the descriptive adequacy and explanatory adequacy of Linguistic Theory using examples from English and other languages.Let us first examine why it is necessary to add a third intermediate grammatical category which is...
