Taking diachronic evidence seriously: Result-oriented vs. source-oriented explanations of typological universals

Classical explanations of typological universals are result-oriented, in that particular grammatical configurations are assumed to arise because of principles of optimization of grammatical structure that favor those configurations as opposed to others. These explanations, however, are based on the synchronic properties of individual configurations, not the actual diachronic processes that give rise to these configurations cross-linguistically. The paper argues that the available evidence about these processes challenges result-oriented explanations of typological universals in two major ways. First, individual grammatical configurations arise because of principles pertaining to the properties of particular source constructions and developmental mechanisms, rather than properties of the configuration in itself. Second,  individual configurations arise through several distinct   diachronic processes, which do not obviously reflect some   general principle. These facts  point to a new research agenda for typology, one  focusing on what source constructions and developmental mechanisms play a role in the shaping of individual cross-linguistic patterns, rather   than the synchronic properties of the  pattern in itself.