A Study On Presupposition Triggers In Barack Obama's Weekly Radio Addresses

Weekly Radio Address is the weekly discussion of current events in the United States by the President(Wikipedia).As a kind of public political speech,it is usually employed by the US president to expatiate viewpoints and attitude,and emphasize the position on national affairs and national relationships.Due to its important role in conveying information,great attention has been paid to it by scholars.Many researches have been conducted on the Weekly Address,mostly from three perspectives-critical discourse analysis,systemic functional grammar,and pragmatics.However,as far as I know,few researches have been undertaken with the guidance of presupposition theory.Presupposition was first proposed by Frege,a German philosopher,in 1892 and later it was studied by many linguists.With more studies on presupposition,researchers have found that presuppositions are closely related to some particular words or aspects of surface structures,which are called presupposition triggers(PTs)(Levinson,2001:179).In the present study,100 transcripts of Obama's weekly radio addresses ranging from January 2009 to January 2016 were selected as the research subject.Based on He Zhaoxiong's classification of PTs,this study,employing quantitative and qualitative methods,investigated the presupposition triggers at semantic and syntactic levels and their functions in Obama's weekly radio addresses.The results are as follows:With regard to PTs at semantic level,it is found that five types are used in Obama's weekly radio addresses,which are definite descriptions,factive verbs,interactives,implicative verbs,change of state verbs.Besides,definite descriptions are used most frequently with the percentage of 89.08% in comparison with other types of PTs at semantic level,while implicative verbs are used least frequently with the percentage of 0.18%.In terms of PTs at syntactic level,six types are used in Obama's weekly radio addresses,which are cleft sentences,temporal clauses,counterfactual conditionals,comparison and contrasts,non-restrictive relative clauses,and questions.Besides,comparison and contrasts are used most frequently with the percentage of 40.15% in comparison with other types of PTs at syntactic level,while counterfactual conditionals are used least frequently with the percentage of 1.23 %.Regarding the function of PTs,it is found that these PTs can make sentences more concise and economical(such as,interactives),make the context more coherent and cohesive(such as,definite descriptions),provide more information(such as,non-restrictive relative clauses),express speaker's attitude(such as,comparison and contrasts),emphasize information(such as,cleft sentences),etc.It is hoped that this study can deepen the understanding of presupposition theory and extend the study scope of presupposition triggers.Meanwhile,this study can enlighten language learners and help them to make appropriate use of different types of presupposition triggers to improve their oratorical language and speech skills.