Full Idea
There are three suggested epistemic conditions on a priori knowledge: the first regards the source of justification, the second regards the defeasibility of justification, and the third appeals to the strength of justification.
Gist of Idea
Epistemic a priori conditions concern either the source, defeasibility or strength
Source
Albert Casullo (A Priori Knowledge [2002], 2)
Book Reference
'Oxford Handbook of Epistemology', ed/tr. Moser, Paul K. [OUP 2002], p.98
A Reaction
[compressed] He says these are all inspired by Kant. The non-epistemic suggested condition involve necessity or analyticity. The source would have to be entirely mental; the defeasibly could not be experiential; the strength would be certainty.