The Study On Motivations And Mechanisms Of Semantic Changes In English Modal Verbs

Modal verbs are frequently used to express people's opinion and attitude to a certain proposition during the daily communication in English. As an important system to express modality, English modal verbs have always received special attention from linguists. In Modern English, studies on modal verbs often mix with studies on modality since the major meaning modal verbs express is modality. Although the study on modality can be traced back to the period of Aristotle, scholars have not reached an agreement on either its definition or its classification, which leads the classification of the meanings of English modal verbs to be a controversial issue in the linguistic field.In recent years, experts in various disciplines are interested in the polysemous phenomenon of English modal verbs and dedicate themselves to studying this issue. For example, pragmatists try to exemplify it based on the relevance theory and the adaptation theory while cognitive linguists attempt to interpret it on the basis of force-dynamics theory and the mapping principle. However, there are more researches indicating that one of the primary causes is semantic changes in English modal verbs.Specifically speaking, English modal verbs, like other systems in English, undergo a complete and complicated process from Old English to Modern English, during which all their phonology, morphology and semantics change greatly. And the morphological shift is the foundation of the semantic change, which also marks each period of the semantic changes. In addition, during the auxiliarization of English modal verbs, their meaning changes from concrete and referential one to abstract and modal one, which is dynamic as well; for example, epistemic modality is evolved from deontic modality.Therefore, this dissertation concludes the path and the regularity of semantic changes in English modal verbs by portraying the historical development of six specific modal verbs, that is, will, can, must, should, ought to and need. Besides, this dissertation not only studies and analyzes the motivations that may cause semantic changes, but also probes into its mechanisms. All these findings will be helpful to the understanding and the use of English modal verbs in communication; since the study on the cross-linguistic universal has become a contemporary trend, approaches applied in the present study may also be adopted by future cross-linguistic researches on modal expressions.