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.