Abstract
Switch-reference is a family of grammatical devices whose primary function is to indicate whether two linked clauses have coreferential pivots, where the pivot is a prominent argument in each clause. In some languages, in addition to their function of reference tracking, switch-reference markers can be used to indicate whether the events or situations described by the two linked clauses differ with respect to some parameter, such as time, place or actuality. This phenomenon is known as non-canonical switch-reference. Whether canonical and non-canonical switch-reference marking are distinct grammatical phenomena is still an open question. In this paper, we investigate uses of switch-reference markers in a corpus of Mbyá Guaraní (Tupian) narratives, and we argue that the alternation between canonical and non-canonical uses is an epiphenomenon of the multifactorial and probabilistic nature of switch-reference marker choice. In this perspective, there is only one grammatical process of switch-reference marking and the distinction between canonical and non-canonical switch-reference marking is matter of language use.