Grammatical Metaphors In Scientific Discourse

Grammatical metaphor is a hot topic in recent linguistic studies.Based on manual marking and computer aiding,the author of this thesis adopts the theoretical framework of Halliday’s classification,aiming to explore grammatical metaphor in different types of scientific discourse.This thesis selects 20 articles on the topic of climate change from the official websites of Science and Scientific American as the data,trying to conduct a comparative study of different representations and their frequencies of ideational grammatical metaphor and interpersonal grammatical metaphor,as well as the functions of grammatical metaphors in the two journals.The ideational grammatical metaphor in scientific discourse is mainly realized by nominalizations.The present study finds different nominalization suffixes in different proportions.Among them,the leading suffixes are-ing,-lion,followed by-ity,-ence,-ness,-ment,-ance,-sion,-ency,-ancy.With more nominalizations and complicated clauses in the texts,Science has higher lexical density and grammatical intricacy than Scientific American has.The results also show that among the six process types of transitivity,material process and relational process are prevailing process types in the two types of scientific texts.The verbal process in Scientific American is higher than that in Science.Nominalization packs a clause in the text into a noun phrase,making the texts highly abstract and information-condensed,which presents experience construction and the characteristics of scientific discourse,including rationality,technicality,abstraction,objectivity,concision and formality.Meanwhile this thesis also analyzes the application of interpersonal grammatical metaphor in the texts.Writers of these texts negotiate with readers by using the first person pronouns,modal verbs,adverbs and adjectives,and at the same time,in order to show being objective in their standpoint,the writers also use words like "research indicates","the results show" to make the tone of the discourse sound objective either in an implicit or an explicit way.The results show that most clauses are declaratives with a few interrogatives and more interrogatives are used in Scientific American than those in Science.The plural form of the first person pronoun we has a higher proportion in Science than that in Scientific American while the singular form of the first person pronoun I has a lower proportion.The low-value modal verbs will and can dominate on the rank in the two types of scientific texts.Therefore,there are important interpersonal motivation and purpose behind objectivity and scientificity in the scientific discourse.Based on Halliday’s theory,the author of this thesis comes to a conclusion that there exist differences between academic scientific texts and popular scientific texts,hoping to provide certain help in scientific reading and writing,as well as the teaching in English science and technology.