To explain the actual meanings of english modal auxiliaries, I introduce the Manyard s Discourse Modality as framework. In dealing with English modal auxiliaries, the framework does not have any trouble in most parts. However, it has to be modified a little to be a comprehensive framework because it was originally proposed not for the English but for the Japanese. With this modified Discourse Modality, I will show that it can comprehend not only general types of modality, which has been already distinguished by many scholars, but also the actual pragmatic aspects of modal auxiliaries, which they have not considered. This is undertaken by analyzing English modal auxiliaries must/have got to and can/may.
2. Maynard s Discourse Modality
3. Analysis of The English Modal Auxiliaries Based on Modified Discourse Modality
4. Summary and Conclusion