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  • 2015-ZhongyiXu-phd.

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Modality and evidentiality in political discourse: a cognitive-functional account

Research output: ThesisDoctoral Thesis

  • Zhongyi Xu
Publication date2015
Number of pages309
Awarding Institution
  • Lancaster University
<mark>Original language</mark>English


This thesis has three main objectives. The first is to propose a new theoretical framework for analyzing modality in political discourse from a cognitive-functional perspective. The second is to explore the types, forms, values and functions of modality in English political speeches both quantitatively and qualitatively. The third is to identify and demonstrate the categories and functions of evidentiality in political discourse, and to discuss its co-occurrence and interaction with modality in the persuasion process.

Drawing on some relevant theories and concepts from Cognitive Linguistics, including Chilton’s model of discourse space, image schemas of space, Langacker’s epistemic model, as well as Halliday’s Systemic Functional Linguistics, this thesis establishes an analytical framework for studying three types of modality (epistemic, deontic and volitional modality) in political discourse from a cognitive-functional perspective. The framework illustrates the functions of modality in political discourse modelled in dimensions of Space, Time and Evidentiality, which interact through deontic distance / epistemic distance / volitional distance, value of modality and strength of evidence.

The framework is applied in a discourse analysis of thirty English political speeches by three politicians: Tony Blair, Barack Obama, Mahmoud Ahmadinejad. Analysing the data both quantitatively and qualitatively demonstrates how different speakers express stance, reflect ideologies and (de)legitimise assertions or actions with different forms, values and types of modality in political discourse. In addition, on the basis of a new classification of evidentiality with regard to its source and mode of knowing, this thesis illustrates the functions of six types of evidentials in political discourse. It is suggested that the adoption of different sources of evidentials reveals the speakers’ corresponding commitments toward their stance and marks subjectivity and intersubjectivity of their stance. Some types of evidentiality reflect the speaker’s ideology as they encode presuppositions about authorities, facts or shared knowledge. It is also argued that there are five patterns in the co-occurrence of modality and evidentiality at the sentential level: Evidentials as SOURCE of Evidence for modal stance; epistemic modality as PART of evidentials; a concessive relation; a conditional relation; a coordinative or progressive relation.