A Note on the Logic of (Higher-Order) Vagueness

The vagueness of a predicate 'Fe' consists in there being no sharp distinction between the objects which satisfy it and those which do not. Hence, it ought to be possible for there to be objects a and b, where a is F, but b is not F, and a (doubly well-ordered) series of objects 'connecting' a to b such that there is no F-'boundary' between any two adjacent objects in the series. What gives rise to the so-called Sorites Paradox is the thought that, where x' is the next object in such a series after x, the vagueness of 'Fe' ought to imply or even to consist in the truth of the following: