Synchronic vs. Diachronic Explanation and the Nature of the Language Faculty

The nineteenth century conception that linguistic structure was to be explained by recourse to the histories of languages was largely abandoned with the rise of synchronic theories in the twentieth century, but has recently returned to prominence. While traditional generative theories of language have tended to attribute cross-linguistic regularities to constraints imposed on the class of possible grammars by the human Language Faculty, some scholars have argued that this is often a mistake: that there are no (or at least very few) real substantive universals of language, and that the regularities in question arise on the basis of common paths of diachronic change having their basis in factors outside of the defining properties of the set of cognitively accessible grammars. This review surveys evidence for that position, primarily in the domain of phonology but also including morphology and syntax. It is argued that in phonology, there are at present no convincingly demonstrated substantive universals governing the set of possible regularities, and that the generalizations we find should be attributed to a combination of contingent historical developments and biases in the learning algorithm that relates available data to the grammars learners acquire. In morphology and syntax, it is argued that some apparent generalizations are indeed the product of diachronic change rather than synchronic constraint, though no broader conclusion is attempted.