Here’s a question about norms of assertion. As I see it, it makes little sense to require that the norms be indefeasible, so I’ll assume here that they’re not.
This assumption is useful for a variety of cases where we don’t seem to demand much of assertion. For example, we don’t complain when Gil Harman disavows believing the things he defends in print. Maybe the audience was in shock at the admission, but I doubt it. Now, if he had said he thought what he defends is false and thought so at the time of the defense, he’d probably hear about it. But in theoretical contexts, it looks like lack of belief does not always raise ire, and need not.
The same point about philosophical assertion holds for the positive epistemic status needed for knowledge. Most of us know that we don’t know the truth of the positive theses we assert. And our audiences know that as well, but they don’t complain that we have no business opening our mouths.
Positing defeasible norms of assertion allows quite a range of views on the matter to be compatible with these data. The question is whether the data about cases where belief and justification (of the sort needed for knowledge) are absent can all be handled by the defeasibility admission. Thoughts appreciated.