Double modal constructions (DMCs) such as 'I might could get it for you' are employed by speakers of Southern American and African American English. These constructions appear to counter-exemplify traditional analyses of English modal structure which typically (i) allow only one tensed element per clause and (ii) locate modal auxiliaries only in the tensed position. Previous analyses have attempted to account for these structures by treating DMs as single lexical units (Di Paolo, 1989), or by treating one of the two modals as a "non-modal" (Turner, 1981; Battistella, 1995; Marrano, 1998; Van Gelderen, 2003). Di Paolo’s lexicalist analysis is contraindicated by the separability of the constituent modals, while the others are contradicted by the modals’ tense-like behavior. Following observations in McDowell (1987), we claim that 'might,' 'may,' and 'must' (in their epistemic readings) are sentential polarity operators (P-modals). P-modals head a POLP (Cormack and Smith, 2002), must raise at LF to take scope over the proposition, and may also bear Tense (in which case they move to T at LF). V-modals (i.e., all other modals) head VP and behave as AUX verbs, moving to T overtly when they bear Tense. Under this account, both modals in the DMC can be analyzed as true modals, behaving exactly as they would in a single modal construction. They are, at the same time, syntactically distinct, and the properties of the DMC result from the interactions between these two modal types.
Elsman, Minta and Dubinsky, Stanley
"Double Modal Syntactic Patterns as Single Modal Interactions,"
University of Pennsylvania Working Papers in Linguistics:
1, Article 10.
Available at: http://repository.upenn.edu/pwpl/vol15/iss1/10