A Study On Ideational Grammatical Metaphor In Scientific Discourse

Since the philosophical trend of thinking prevalent from logical positivism to relativity in 1960s, the truth has been considered as a hypothesis not perpetual and final. Influenced by this philosophical thinking, linguists advocated that science language should not be described in literal language to depict the eternal truth but should be conceived as the thinking activity to illustrate and reconstruct the world. Based on those linguists' points of view, this thesis intends to explore the phenomena of grammatical metaphors in scientific discourse especially the application of grammatical metaphor theory proposed in systemic-functional linguistic in scientific discourses.This thesis firstly introduces Halliday's grammatical metaphor theory. Based on the contributions to the study on grammatical metaphor theory, it expounds the theory of "congruence" and "incongruence" and multi-levels language system. Secondly, it demonstrates the generation, realization and transference of grammatical metaphor through the transitivity processes and thirteen types of ideational grammatical metaphor proposed by Halliday. Thirdly, this thesis depicts the nominalization, rank-shift phenomenon and favorite grammatical pattern formed in process of ideational metaphor's realization.On the basis of Halliday's GM theory, taking the method of quantitative analysis, this thesis analyzes the application of grammatical metaphor theory in scientific discourse. I proceed to conduct the data of ideational grammatical metaphor types in 36 abstracts from English scientific papers and illustrate the total ideational grammatical metaphor types in six English scientific discourses with the criterion of 13 types of ideational grammatical metaphor that Halliday classified. Simultaneously, I also probe the relations between register and ideational grammatical metaphors by the comparison of two categories of scientific discourses with the method of quantitative analysis.According to the statistical analysis, this thesis draws the following conclusions:1. The ideational grammatical metaphors in scientific discourse are principally realized in the form of nominalization and adjectivization and the frequency of occurrence of nominalization ranks highest.2. The technical terms used in scientific discourses are determined by the field of register.3. The text with the same status of participants is more difficult than that with the different status of participants.4. Different extent of written form in discourses presents different lexical density and numbers of ideational GMs.5. In scientific English, a large amount of information expressed by clauses is packed or condensed into nouns or nominal groups through grammatical metaphors so as to make the clauses with more succinct structures and abundant information. The use of grammatical metaphor makes the scientific discourse more technical, objective, precise and persuasive. The nominalization can be unpacked and it would lower the difficulties in great extent after unpacking, providing some helps for language learners to read and comprehend scientific discourses.