| As a rather formal genre, academic writing has been one of the most important elements of a successful scholar. It has been widely known that academic discourse is noted for its scientific objectivity, with transmitting the latest information to academic community as its main goal. The traditional view puts more emphasis on the impersonal features of academic discourse by ignoring its interactive interpersonal features. Systemic Functional Grammar holds that discourse is an interaction among social members. The process of academic communication itself is a social interactive process by which the writer attempts to present and clarify his views. It has been found that hedges, which express uncertainty, tentativeness and possibility, are playing significant roles in academic discourse. The lack of them may lead to an unfavorable academic understanding or even misunderstanding between readers and writers. Despite its importance, however, we know little about how hedging is expressed or the functions it serves in different disciplines or genres.This thesis, therefore, based on previous studies, presents a corpus-based contrastive analysis of hedges between two disciplines. Observing kind of overlap between hedges and modality, the author conducted an interface analysis of them from semantic, pragmatic, lexico-grammatical aspects respectively and consequently, hedging modal operators (HMOs) and hedging mood adjuncts (HMAs) were put forward as two working definitions in this research. The author compiled two corpora which consist of the Discussion sections of twenty research articles (RAs) in the field of medicine and sociology respectively. Both qualitative and quantitative analysis was made. In the section of hedging modals analysis the author mainly confined the forms to some selected HMOs such as may, might, can, could, will, would, shall, should and must, and HMAs such as certainly, probably, possibly, perhaps, maybe. With Halliday's modality system under the interpersonal metafunction as a theoretical framework, the purpose of this research was to prove the importance of hedging in academic discourse and find out the similarities and differences across disciplines. The research was hoped to help researchers or students to read and write such a Discussion section more effectively and efficiently.The results suggest that the striking disciplinary difference is that hedging modals are used much more frequently in sociology than in medicine with the total occurrence frequencies 118.1 per 10,000 words and 78.7 per 10,000 words respectively. Besides, there are also some similarities and minor differences between them. The analysis shows that by employing these wordings, it is possible for academic writers to present their knowledge stance with caution and construct an interpersonal framework oriented to the interaction between writers and readers. |