A crosslinguistic study of conditions on argument indexing

Abstract This paper presents a systematic study of conditional argument indexing in 83 genealogically diverse languages. ‘Indexing’ means a form of marking (affixal, clitic, or non-linear) on a verb that expresses one or more features (person, number, gender/noun class) of an argument. ‘Conditional argument indexing’ is when a particular argument is not indexed (or indexed differently) under certain conditions. We study all three (in)transitive core arguments and a wide range of conditions, including referent properties (e.g., person, animacy, discourse prominence), TAMEP (tense, aspect, mood, evidentiality, polarity), event semantics, lexical factors, and co-occurrence of an independent argument. Our results show that conditional indexing systems are typically conditioned by more than one factor and that lexical restrictions are often involved. Also, while conditional indexing is attested in similar proportions across the three argument roles, it tends to be triggered by different factors for each role. Unlike in earlier studies of differential argument flagging, this study shows that referent properties have similar effects on argument indexing for each role, in terms of the values associated with the presence or absence of indexing. These findings have implications for the communicative function and grammaticalization of (conditional) indexing.