This document provides an overview of epistemological foundations from rationalism to positivism and beyond. It discusses rationalist approaches from Descartes that sought to deduce knowledge from reason and certainty. It then examines empiricist views from Locke that knowledge comes from sensory experience. Positivism developed as an epistemology where genuine knowledge is based on observable evidence through science. However, later post-positivist thinkers like Popper, Quine, and Kuhn challenged positivism by arguing theories cannot be fully verified and scientific paradigms change for complex non-rational reasons.