Can and future meaning

Can is traditionally seen as having three general meanings, ability, permission, and possibility (Leech 1987). However, as noted by Coates (1983), in certain cases the function of can is somewhat similar to that of will, e.g. offering to help by saying I can/will help, if you want, asking for help by saying Can/will you pass the salt please?, etc. Using a database of 119 naturally-occurring tokens of can followed by a main verb with future time reference (Trudeau 1984), the present paper posits 17 distinct functions of can, of which 7 show a semantic affinity with will. Those functions having a semantic affinity with will generally have a number of distinctive characteristics: they are associated with possibility rather than ability or permission, they are characterized by interactive or syntactic rather than semantic properties, and analysis of early 19th century texts shows that they have only developed in the language relatively recently. This suggests that, to a large extent, the possibility function of can represents a recent encroachment into the functional territory of future tense marking.