Full Idea
We should distinguish 'constitutive scepticism' (about the existence of certain sorts of facts) from the traditional 'epistemological scepticism' (which concedes that the sort of fact in question exists, but questions our right to claim knowledge of it).
Gist of Idea
Constitutive scepticism is about facts, and epistemological scepticism about our ability to know them
Source
Alexander Miller (Philosophy of Language [1998], 4.7)
Book Reference
Miller,Alexander: 'Philosophy of Language' [UCL Press 1998], p.132
A Reaction
I would be inclined to call the first type 'ontological scepticism'. Miller is discussing Quine's scepticism about meaning. Atheists fall into the first group, and agnostics into the second. An important, and nicely simple, distinction.