Opinion Is The Medium Between Knowledge

From Republic Book V (477a–478e), where Plato distinguishes knowledge (episteme), opinion (doxa), and ignorance (agnoia) by their objects. Knowledge grasps what fully is (the Forms); ignorance is directed at what is not; opinion occupies the intermediate territory of the visible, changing world of appearances. This epistemological scheme underpins the famous Allegory of the Cave in Book VII and explains why Plato was suspicious of democracy: the many, operating on mere opinion, are not equipped to govern wisely.