The Basis of Knowledge from Reuben Abel's 1976

8)

1. sense perception-only what is true can be known 
2. logic-one can believe without knowing but one cannot know without believing 
3. intuition-to distinguish knowledge from a lucky guess
4. self-awareness-the evidence of true belief could be destroyed with knowledge 
5. memory-memory is no guarantee of truth 
6. authority-authority is a justification of knowledge
7. consensus gentium  ('everybody says so')-before disregarding the justification of knowledge we must examine the basis of truth
8. revelation-it is a reason of justification that seems unreliable
9. faith-faith is a requisite of knowledge but not  a guarantee of it