Exaptation and degrammaticalization within an acquisition-based model of abductive reanalysis

This article considers the relationship between exaptation and degrammaticalization. Both may involve obsolescent material being re-used, to express an existing grammatical category or a category not previously encoded. The processes involved are familiar ones: reanalysis triggering category reassignment. In both cases, change is caused by failure to acquire a grammatical category. Faced with material that expresses that category, acquirers either interpret it as some existing category or else abduce the existence of some new category. Exaptation and degrammaticalization are thus understood as cases of reanalysis within an acquisition-based framework of change. The concept of exaptation is therefore useful but not foundational: useful in highlighting unexpected pathways of development during ongoing obsolescence or opacity, but explicable in terms of other processes. I demonstrate this approach using two case studies: degrammaticalization of indefinite pronouns as nouns in Slavic and Celtic; and exaptive reinterpretation of the was-were distinction as expressing polarity in English dialects.