Full Idea
Appeals to intuition - no matter how informal - can hardly fail to smack of the synthetic a priori.
Gist of Idea
Appeals to intuition seem to imply synthetic a priori knowledge
Source
José A. Benardete (Metaphysics: the logical approach [1989], Ch.18)
Book Reference
Benardete,José A.: 'Metaphysics: The Logical Approach' [OUP 1989], p.136