A factive attitude report implies the truth of its prejacent, as in "Mary knows that Harry left." Here, factivity turns on the choice of embedding verb ('know'), but sometimes, (non-)factivity turns on complement clause syntax, both in English (Schueler 2016) and in such languages as Turkish (Özyıldız 2017), Barguzin Buryat (Mongolic) (Bondarenko 2020), and Korean (Lee 2019). We focus on factivity alternation in Korean knowledge reports. We propose to model this alternation as reflecting an underlying modal base that is epistemic and therefore in principle factivity-inducing, but that can be supplemented with a stereotypical ordering source signaled by -URO ‘toward’ that undoes the factivity. The proposal implies that grammatically induced variation in modal parameter settings (here, the presence vs. absence of a stereotypical ordering source) constitutes one (heretofore unrecognized) source of factivity alternation in natural language.
