Has anyone working on knowledge attributions looked into the expression “common knowledge”? It’s different than a lot of uses of “knowledge” because it takes a ‘that’-clause (as compared to”knowledge of” a domain, as in: “She has knowledge of physics”). So aside from questions about what I have to know to have knowledge of a domain, there’s a question of what has to be the case for it to be common knowledge that p (or for it to be proper to say that it is common knowledge that p). I’m more interested in the “knowledge” part than in the “common” part, since there’s nothing at all defective about saying “It was common knowledge that p, but not-p.”
Suppose sentences like that can be true. Intuitively, there is a close conceptual connection between what is known and who has knowledge, i.e.:
Linking Principle: S has knowledge that p only if S knows p.
On the face of it, common knowledge is a kind of knowledge, namely, knowledge had by some salient class of (common) people, i.e.:
Definition of Common Knowledge: It is common knowledge that p (for some class of people C) iff sufficiently many of the members of C know that p.
It follows, from our supposition that “It was common knowledge that p, but not-p” can be true, that “S knows p” and “not-p” are compatible.
Is there some other account of “knowledge that” and “common knowledge” available, which isn’t committed to the Linking Principle and the Definition of Common Knowledge presented above? (It seems to me that similiar questions concern the expressions “scientific knowledge,” “folk knowledge,” etc., as well as sentences of the form: “As far as S knew, p”.)