Knowability Principle and Disjunction Property

The so-called paradox of knowability is usually regarded as questioning the principle that all truth is knowable (knowability principle). In this paper we examine the connection of the principle of knowability with other principles (epistemic versions of the disjunction property), which concern the relationships between knowledge of a disjunction and knowledge of the disjuncts, and between knowledge of an existentially quantified sentence and knowledge of one of its instances. Some epistemic versions of the disjunction property are apparently weaker than the knowability principle. Still one of them seems to have paradoxical, or at least not easily acceptable, consequences as well. This puzzling result is diagnosed as depending on the association of a strongly intensional view of propositions with the impredicative way in which they are conceived and dealt with. If correct, the diagnosis directly applies to the paradox of knowability as well.