Case and agreement alignment in ditransitive constructions: A typological gap and its explanation

I describe a typological gap in case and agreement alignment in ditransitive constructions. In languages in which verbal agreement is controlled by the subject and at most one object, object case and agreement in ditransitive constructions do not exhibit all logically possible combinations of alignment. I show that this typological gap follows from assumptions about the structure of ditransitive constructions (recipients c-command themes) and the interaction of morphological case and agreement (case marking restricts agreement). These assumptions derive exactly and only the attested patterns of alignment. I also argue that the typological gap in ditransitive constructions has a parallel in transitive constructions, providing further support for the proposals made here.