Instrumental prepositions and case: Contexts of occurrence and alternations with datives

We will argue that instrumentals are the mirror image of dative/genitive obliques. We propose that both sets of adpositions/cases are elementary predicates, expressing a zonal inclusion (partwhole/possession relation); instrumentals reverse the direction of the relation with respect to datives/genitives. Our claim is that with-type morphemes provide very elementary means of attaching extra participants (themes, initiators, etc.) to events (VP or vP predicates) - with specialized interpretations derived by pragmatic enrichment (contextual, encyclopedic) at the C-I interface. We will extend our proposal to account for the observation that the instrumentals can be employed crosslinguistically in triadic verb constructions alternating with datives and we will broaden our discussion to account for dative/instrumental syncretism (eventually including DOM objects), arguing that the inclusion predicate (subset of) corresponding to 'to' or dative case and its reverse (superset of), corresponding to 'with' or instrumental case, may reduce to an even more primitive content capable of conveying inclusion in either direction. Finally, we will address ergative alignments, showing that languages may attach external arguments/agents either as possessors (subset of) or as causers (superset of) of a given event/state, yielding the two most widespread patterns of syncretism of the ergative morpheme, that is with either instrumentals or genitives/datives.