From demonstrative to conjunct: Grammaticalization of the Korean conjunct ku-kes-to ‘on top of that’

This study draws on both historical corpora and present-day natural conversation corpora and employs the theoretical concepts of grammaticalization and cooptation to investigate the development of a Korean demonstrative construction into the scalar additive conjunct ‘on top of that’. The source construction ku-kes-to ‘even that’, composed of ku-kes ‘that thing’ and to ‘also’ or ‘even’, was first attested in the 19th century. In the intermediate stage of the 1920s, it started to be construed both as ‘even that’ and ‘on top of that’. In the 1930s, it became fully grammaticalized as the conjunct 'on top of that', and it also began to form a thetical (or parenthetical) inserted into another sentence while remaining syntactically and prosodically detached from it. From the 1940s onward, it continued to expand its range of use, appearing in increasingly diverse positions, including those without a preceding NP, having lost its demonstrative attributes. As the first study to examine the development of the conjunct ku-kes-to , this study delineates the construction’s step-by-step changes, with particular attention to the critical period from the 19th century to the 1940s. The study argues that the development of the conjunct ku-kes-to simultaneously involves textualization, subjectification, and intersubjectification. In doing so, it provides supporting evidence for Traugott’s (2022, 2024) recent proposal that, contrary to her earlier accounts (e.g., 1982, 2003), no fixed historical ordering can be generalized among these three processes.