On The Origin Of The English Clause Introducer That

That is one of the most frequently-used words in English. In traditional grammar, that has dual status:as a demonstrative pronoun or a clause introducer. In order to explain this kind of synchronic variation existing in the usages of that, this thesis explores the differences and relationship between the two instances of that from a diachronic angle. Therefore, the thesis discusses the diachronic evolvement of that from a demonstrative pronoun to a complementizer via grammaticalization within the framework of Generative Grammar, emphasizing on its course, motivation, mechanism and the pathway it follows, and thus to reveal the origin of the English clause introducer that.Grammaticalization is a process in which lexical items develop into functional items or the existing functional items transform into new ones which have more functions. As a pervasive diachronic change of language, grammaticalization has been the topic of functionalism and was even viewed as a challenge to formalism. Based on the previous studies on grammaticalization from a formal perspective, this thesis argues that grammaticalization results from the change of parameter setting, which is caused by the ambiguity of the triggering experience provided by input, and that the creation of the new functional category is owing to the change of the way in which the functional head gets realization in PF.According to the above analysis, this thesis explores the origin of the English clause introducer that within the framework of Generative Grammar. At the beginning, the thesis makes certain the syntactic status of the clause introducer that by adopting the complementizers theory in Generative Grammar. That is a complementizer which belongs to functional categories and hasn’t descriptive content but carries grammatical meaning, either introducing nominal clauses or introducing relative clauses. Then the thesis takes a comparative study between the complementizer that and the demonstrative that, and points out that the former is weaker than the later in phonological, morphological, semantic and syntactic aspects, and that the two instances that can be regarded as synchronically distinct lexical items belonging to different categories. Next, the thesis probes into how this categorical change took place, namely how the complementizer that developed out of the demonstrative that. In this thesis, according to the author’s analysis, there are two steps involved in the development of the complementizer that. The first is the innovation of a finite complement clause (CP), at the expense of an adjunction clause which is coreferent with a demonstrative that in the main clause. The latter is the consequence of the former in the sense that the new embedded finite CP triggers the reanalysis of the demonstrative that as a complementizer that. This diachronic process involves two structural simplifications correspondingly. The first one is the elimination of adjunction structure [IP IP CP] in favor of the head-complement structure [v’V CP]. The second one is the loss of C*Move in favor of C*Merge when the functional head C requires realization in PF, thus the demonstrative that is reanalyzed as a complementizer. These two structural simplifications are associated with the built-in conservative nature of language acquirers. When the triggering experience provided by input becomes obscure or ambiguous, the language acquirers will opt for the simpler representation. Lastly, the thesis points out that the grammaticalization of that is an instance of "upward" reanalysis along with the hierarchy of the functional heads (C>D)Through the diachronic study of that within the framework of Generative Grammar, the thesis reveals the origin of the complementizer that, namely, it derived from the demonstrative that via grammaticalization, which explains the synchronic variation between these two instances. And this study also proves that the formal approach to grammaticalization can give novel insights to the mechanism, motivation and pathway of grammaticalization, and thus accounts for the nature of grammaticalization more effectively.