Potential grammaticalization of epistemic phrases

Abstract This paper deals with the potential grammaticalization of English (it) could be and (it) might be into epistemic sentence adverbs in analogy to maybe . They can occur in adverb-like positions and functions in informal language use, e.g. (it) could be something good has begun , often with the pronoun it omitted. But, given that no diachronic development is attested, to what extent does their usage indicate innovation or an emerging convention of adverbial could be / might be ? How are they differentiated from maybe ? Following up on previous corpus-based and experimental research, I present findings from two small experiments. Experiment 1 elicits the morphosyntactic interpretation (clausal vs. adverbial) with ratings of structurally different paraphrases; Experiment 2 aims at the semantic interpretation of epistemic stance. The results provide little evidence of conventionalization of adverbial could be / might be , and also no clear signs of semantic or pragmatic differentiation. I conclude that weak conventions leave room for variability, and propose that these forms have a proclivity to be continuously re-innovated as micro-steps on a grammaticalization path, but this is not enough to drive change beyond existing conventions.