A Study Of Grammatical Metaphor In Science And Technology Discourses Of TED Speech

In 1985 of his book An Introduction to Functional Grammar,Halliday put forward the concept of “Grammatical Metaphor” for the first time,which states that metaphor is not only confined to the lexical level,but exists on the grammatical level,and the metaphor on the grammatical level is grammatical metaphor.The concept of“grammatical metaphor” caused a big hit in the linguistics field.With the development of grammatical metaphor,Halliday further reclassifies this theory in 1996.He divides grammatical metaphor into 13 types,which is the refinement of the type of GM.Since grammatical metaphor came into being,many researchers have applied this theory into all kinds of discourses,such as advertisements,literature,translation,public speech,etc.Among public speech,there is a lot of research on grammatical metaphor in political speech,presidential addresses,and university commencement speech.However,research about TED speech which becomes more and more popular nowadays is rare,especially about the science and technology discourses of TED speech.Based on Halliday's 13 types of ideational metaphor and interpersonal metaphor in Systemic Functional Grammar,this research aims to find out the distribution features,main realization forms and functions of ideational metaphor and interpersonal metaphor in 30 science and technology discourses of TED speech respectively,through which the textual characteristics of such kind of discourses are revealed and how speakers make use of ideational metaphor and interpersonal metaphor to successfully construct science and technology discourses is illustrated.Hopefully this research can help English learners better understand science and technology discourses of TED speech and master the writing skills of science and technology speeches.This research downloaded 30 science and technology discourses of TED speech(from 2003 to 2016)randomly from its official website www.TED.com.,which covers five fields: physics,energy,environment,computer and biology,each of which contains 6discourses.With the quantitative and qualitative research method,this paper aims toanswer the following three questions:(1)What are the distribution features of ideational metaphor in science and technology discourses of TED speech? What are its dominant realization forms?(2)What are the distribution features of interpersonal metaphor in science and technology discourses of TED speech? What are its dominant realization forms?(3)What are the common functions of ideational metaphor and interpersonal metaphor in science and technology discourses of TED speech respectively?The research result reveals that a huge amount of grammatical metaphor exists in science and technology discourses of TED speech.As for ideational metaphor,nominalization and adjectivation take larger proportion.Verbalization and prepositionalization are the least used type.Type 1(quality? entity),Type 2(process?entity),Type 5(process? quality)and Type 6(circumstance? quality)are the most frequently used type of ideational metaphor.There are three main functions of ideational metaphor: to enrich sentence meaning(achieved by packaging information);to simplify sentence form(achieved by degradation in rank-shifting);to achieve textual coherence.As far as interpersonal metaphor is concerned,it is far less frequently used than ideational metaphor.The number of metaphor of mood is a bit larger than that of metaphor of modality.In metaphor of mood,the speakers are more likely to use declarative mood to express interrogative mood and use interrogative mood to express declarative mood,while imperative metaphor seldom occurs.The function of metaphor of mood is to form atmosphere of intercommunication and highlight important information.As for metaphor of modality,explicit subjective form of modality is more frequently used than explicit objective form of modality and nominalization of modality.One of the functions of the former is to express the speaker's subjective ideas.Another function is to show the speaker's uncertainty to what he/she states.The function of the latter is mainly to make what the speaker claims more objective so as to increase its persuasiveness.