Grammaticalization and Explanation

A recurring theme in a special issue of Language Sciences (2001) devoted to theoretical debates about grammaticalization is that the causal mechanisms subserving examples of grammaticalization are explanatorily exhaustive and that the concept of grammaticalization itself is therefore empty. The position seems to be a straightforward inference from the assumption that explanation must appeal to causal mechanisms, together with the recognition that grammaticalization is not itself a causal mechanism. While this position is unobjectionable, perhaps even unassailable, in addressing questions of the form How did grammaticalization-examplex occur in languagey? there are other questions that seem to be better addressed by appealing to the concept of grammaticalization itself. In particular, questions of the form What makes language-change-examplex specifically an example of grammaticalization? are best answered by appealing to the fact that it satisfies the concept or definition of grammaticalization. Satisfying the definition of grammaticalization, in turn, requires identifying the language change example specifically as one involving a lexical to grammatical change (or a change from less grammatical to more grammatical), regardless of the causal mechanisms involved in that change. That is, it is only under the description of the phenomenon as a change from lexical form to grammatical form, that the mechanisms typically adduced to explain this change can be said to be explaining it as an instance of grammaticalization.