Full Idea
There are plenty of necessary truths that we are unable to express, let alone know a priori.
Gist of Idea
Many necessities are inexpressible, and unknowable a priori
Source
Philip Kitcher (A Priori Knowledge Revisited [2000], §II)
Book Reference
'New Essays on the A Priori', ed/tr. Boghossian,P /Peacocke,C [OUP 2000], p.69
A Reaction
This certainly seems to put paid to any simplistic idea that the a priori and the necessary are totally coextensive. We might, I suppose, claim that all necessities are a priori for the Archangel Gabriel (or even a very bright cherub). Cf. Idea 12429.
Related Idea
Idea 12429 Knowing our own existence is a priori, but not necessary [Kitcher]