On being certain whether
This contribution deals with the question of why certain predicates, in particular be certain, that normally cannot embed interrogative clauses nevertheless do so when they occur in special contexts. A satisfactory answer to this question requires specifying the general conditions under which predicates can combine with interrogatives. Since, as is well known, such a specification is hard to come by, the larger part of the article is devoted to this question. It will be argued that, counter to the factivity hypothesis, it is reasonable to assume that the restrictions on the combinability of predicates with interrogatives are not rooted in general semantic properties of the predicates, but ultimately in the typical properties of question situations and the knowledge we have of these properties.