Modality in SFL Revisited: Establishing Evidentiality in the System of Modality

In systemic functional linguistics (SFL), modality is seen as an extension of the semantic space of polarity. The SFL perspective provides a unique insight into the complexity of modality. However, it has received little attention in the open literature, and the SFL categorization of modality seems out of place compared to other perspectives. The purpose of this paper is to address the potential problems with the categorization of modality in SFL and to establish evidentiality in the system. To this end, the present study reviews the development of modality in SFL and justifies the need to replace usuality with evidentiality. The results show that there are four stages in the development of modality in SFL and that usuality, as a subtype of modality, faces challenges both from the later development of modality and from studies of grammatical metaphor in SFL. The paper then argues that the categorization of modality should be made along two dimensions, namely modality force and modality locus, and that evidentiality should take the place of usuality as a category in the system. The study also shows that evidentiality can be further divided into four types, and that it has eight ways of realization.