Why do-support in Scots is different

Previous work on Scots syntax tends to assume that do-support follows the English pattern (e.g., Görlach, A Textual History of Scots) despite the fact that Scots exhibited variability between do-support and verb-raising for much longer than English (e.g., Jonas, “Residual V-to-I”). Do-support is still not categorical in all dialects of Modern Scots, and this variability highly correlates with a phenomenon present in Scots but not in (Standard) English: the Northern Subject Rule (NSR) (e.g., Smith, “Negative do in Buckie Scots”). This paper builds on de Haas's (De Haas, “Morphosyntactic variation in Northern English”) claim that the -(i)s inflection, employed in Scots NSR varieties to establish subject-verb agreement in environments where Standard English would employ do-support, is in fact a default inflection, while the ø-inflection found where plural pronouns are immediately adjacent to the finite verb is true subject-verb agreement. It will argue that do-support in Scots is more likely to be a transfer from English than an independent development. The variability in the development of Scots do-support is argued to be due to Scots retaining other means of establishing subject-verb agreement, the NSR and verb-raising. Thus, do-support was either acquired for a different function, i.e., as a negation or question marker, or the variability is due to do-support entering a three-way grammar competition to express the same function as the NSR and verb-raising.