One of the questions that still surrounds the history of auxiliary do is what function it had during the Middle English period (c.1100–1500). Scholars have put forward different hypotheses, suggesting that it could serve, among others, as a perfective marker (Denison 1985), agentive marker (Ecay 2015) and habitual marker (Garrett 1998). The present article reports on a quantitative study that aims to shed further light on this issue. By means of a collexeme analysis, this article investigates the semantic features of the infinitives that occur with auxiliary do in several Middle English corpora. The results show that auxiliary do was not connected to verbs with specific semantic profiles, but it was employed in different contexts and had various functions. Specifically, the data suggest that auxiliary do was used (i) as an accommodation tool to facilitate the use of low-frequency verbs, particularly of French origin, and (ii) as an aspectual particle to mark both perfectivity and habituality. It is argued that the multifunctionality of auxiliary do in Middle English played a crucial role in the preservation of the construction before it spread to the NICE (i.e. negation, inversion, code and emphasis) environments.

The DO in “Subject DO Predicate” sentences is often associated with unexpected meaning, including contradictory uses in dialogue where DO functions as a sort of reassertive marker and in monologal contexts where a speaker short-circuits potential objections. Many instances of affirmative DO do not fit into this category, however. These involve quasi-exclamative use, non-polemical use in dialogue or gnomic confirmation. Often considered prototypical, contradictory DO represents only one possible configuration: other uses can be accounted for as paramétered variations of a single fundamental operation. Affirmative DO marks speaker endorsement. Values of affirmative DO — polemical, concessive, exclamative, etc. —are shown to result from the relation between various preconstructed subjective positions and the speaker’s own position.