My some times mischievous friend Richard Grandy once said, in connection with some other occasion on which I was talking, that to represent my remarks, it would be necessary to introduce a new form of speech act, or a new operator, which was to be called the operator of quessertion. It is to be read as “It is perhaps possible that someone might assert that ...”, and is to be symbolized “?⊢”; possibly it might even be iterable.
Grice, “Meaning Revisited”