Explaining similarities between main clauses and nominalized phrases

In many languages of South America, there is substantial morphosyntactic parallelism between nominalized clauses and main clauses. In particular, it is often the case that a single series of personmarkers occurs on inalienable nouns to indicate the possessor; this same series of person-markers also occurs on both nominalized and main clause verbs to indicate one of the core arguments of the verb. Constituency often parallels these morphological markers, with the possessors of nouns and nominalized verbs forming the same type of constituent with their heads as the parallel core argument forms with the main verb. This paper considers such parallelism in two language families and one genetically isolated language of Amazonia. Having established the existence of the pattern, we next ask why such parallelism should exist and why it should be so common. The short answer is that the patterns share a common origin, in which (i) nominalizations serve as complements of abstract matrix clause verbs, then (ii) these biclausal constructions are reanalyzed as monoclausal main clause predicates, in which the erstwhile nominalized verb is now the semantic and syntactic