Which Type of Knowledge is the Subject of a Philosophical Analysis?

Epistemologists usually assign three meanings to knowledge. Familiarity, skill and propositional (predicate) knowledge constitute three meanings of knowledge. Most epistemologists, however, consider propositional knowledge as the subject of philosophy. Using a library and qualitative method, the present paper tries to shed light on each meaning of knowledge, study propositional knowledge in particular and investigate the three conditions of this definition and the views proposed about them, on the basis of the traditional definition of knowledge of justified true belief. The research findings indicate that some epistemologists consider these three conditions as problematic and that although there has been a relative consensus on the definition of knowledge in terms of these three conditions, it has been challenged and these three conditions has been regarded as imperfect since Gettier's time.