Differential argument marking: Patterns of variation

In this introductory article we provide an overview of the range of the phenomena that
can be referred to as differential argument marking (DAM). We begin with an overview of
the existing terminology and give a broad definition of the DAM to cover the phenomena
discussed in the present volume and in the literature under this heading. We then consider
various types of the phenomenon which have figured prominently in studies of DAM in
various traditions. First, we differentiate between arguments of the same predicate form
and arguments of different predicate forms. Within the first type we discuss DAM systems
triggered by inherent lexical argument properties and the ones triggered by non-inherent,
discourse-based argument properties, as well as some minor types. It is this first type that
traditionally constitutes the core of the phenomenon and falls under our narrow definition
of DAM. The second type of DAM is conditioned by the larger syntactic environment, such
as clause properties (e.g. main vs. embedded) or properties of the predicate (e.g. its TAM
characteristics). Then, we also discuss the restrictions that may constrain the occurrence
of DAM cross-linguistically, other typical features of DAM systems pertaining to the mor-
phological realization (symmetric vs. asymmetric) or to the degree of optionality of DAM.
Finally, we provide a brief overview over functional explanations of DAM.