Using phonotactics to reconstruct degrammaticalization

The principle of directionality is an important part of the comparative method: in order to arrive at a reconstruction, historical linguists need a robust theory that informs them in what direction linguistic change is likely to proceed. But any such theory will have exceptions. How are these to be spotted? I examine one case in which a counter-directional change, degrammaticalization, can be reconstructed by invoking the phonotactics of the proto-language. The degrammaticalized form is the Sirva 3sg pronoun be, and the proto-language is Proto-Sogeram. After making this reconstruction, I also demonstrate that it can be used to enhance our understanding of degrammaticalization. Be spawned a small family of related forms, which shows us that degrammaticalized forms can become polygrammaticalized in the same way as other grammatical morphemes.