Constructional blending: the five functions of BE supposed to and BE meant to

The forms BE supposed to and BE meant to are ‘polysynonymous’ and can be used to express a wide range of functions: evidential (hearsay/reportative), deontic (intention/obligation), deontic (prohibition) and predestination. While other verbs in passives can express certain of these functions, only these two have developed the ability to appear in the full range. Following a Construction Grammar approach, this paper focusses on a further, new, function that can be illustrated by the sentence It’s supposed to be good tomorrow (source: BNC KCX4941) Such an example can also contain meant to with no change of meaning. This relatively recent development expresses a ‘report of a prediction’. BE expected to has a similar, but by no means identical function, and can of course also be used with a deontic meaning in a passive construction. However, this new use is not possible with other evidential/hearsay verbs when used in the same syntactic pattern. This paper discusses the semantics and syntactic idiosyncrasies of BE supposed to and BE meant to and concludes that this ‘new’ function is the result of a type of ‘constructional blend’ of the existing hearsay and deontic uses. It is unique to the two focal constructions due to their unique range of use across all the construction types above.