On Coherence Of English Political Speech Discourses From The Perspective Of Thematic Structure

Themes are the starting point of information and the topic concerned,while rhemes are the interpretation and development of the themes.The theme and rheme constitute the thematic structure.The basic unit of thematic structure is clause.Each clause in a text can be divided into theme and rheme parts.The themes and rhemes of the preceding sentences connect with those of the latter sentences in various ways,forming thematic progression patterns.There are linear and hierarchical relations among thematic structures of sentences in a discourse,which connects the topics discussed by the sentences in the discourse.By studying the thematic structure of the sentences in the discourse and the thematic progression patterns formed among them,the cohesive mechanism of discourse coherence can be analyzed.At present,quite a few scholars have studied the thematic structure of various discourse types,including medical texts,newspaper editorials,English and Chinese radio news,English novels,English abstracts,English for science and technology,and advertising English,etc.However,it is rare to find similar studies in English political speech discourses.Therefore,based on previous research results,this thesis attempts to explore the discourse coherence of English political speech discourses from the perspective of thematic structure by taking President Trump‘s weekly address texts as the corpus.This thesis analyzes the thematic and thematic progression characteristics in the selected texts and discusses how the themes and the thematic progression patterns promote the coherence of English political speech discourses.In this study,56 texts of President Trump‘s weekly addresses are downloaded from the official website of the White House.Combined with the random sampling function of Excel,20 texts are randomly selected as a corpus for analysis by using the formula for calculating the sample size in limited population.Each sentence in the selected texts is divided by the theme and rheme,the types of themes and thematic progression patterns are marked and after finishing marking,the amount of each type is counted and their percentages are calculated.The research results show that the proportion of simple theme,multiple theme and clausal theme is 70%,25% and 5% respectively.The simple themes are mainly reflected by noun phrases.Cohesive types such as,reference,substitution,and lexical cohesion are used in simple themes to promote discourse coherence.Among multiple themes,conjunctive,structural and continuative components of textual themes can promote the cohesion and coherence of a text.Besides,interpersonal theme can also play a cohesive role.Each thematic progression pattern promotes coherence in its own way.A total of five progression patterns are adopted in the corpus,and the more frequently adopted patterns are Parallel Progression Pattern and Continuous Progression Pattern,accounting for 39% and 37% respectively.The other three progression patterns,Focused Progression Pattern,Alternative Progression Pattern and Derived Rheme Progression Pattern take up 15%,7% and 2% respectively.Parallel and Continuous Progression Patterns have been much more adopted to make the discourse more concise and the cohesion and coherence more natural,which is consistent with the characteristics of political discourse.