Full Idea
Once the obstacle of the deeply rooted conviction that necessary truths should be knowable a priori is removed, ...causal necessity is (pretheoretically) the very paradigm of necessity, in ordinary usage and in dictionaries.
Gist of Idea
Once you give up necessity as a priori, causal necessity becomes the main type of necessity
Source
Sydney Shoemaker (Causal and Metaphysical Necessity [1998], VII)
Book Reference
Shoemaker,Sydney: 'Identity, Cause and Mind' [OUP 2003], p.425
A Reaction
The a priori route seems to lead to logical necessity, just by doing a priori logic, and also to metaphysical necessity, by some sort of intuitive vision. This is a powerful idea of Shoemaker's (implied, of course, in Kripke).