Philosophers have long been asking: do we have knowledge about the external world? Before we can solve this epistemological problem, there are more fundamental questions that need to be addressed. Since perceptual experience is the most basic access to the external world, it is important to investigate the nature of perceptual experience and its relation to the world. We will devote the entire course to this investigation. We will examine whether Direct Realism眩he thesis that we can directly perceive the physical world, or that the immediate objects our perception are physical things畚an be defended. The main skeptical arguments against Direct Realism are Argument from Illusion and Argument from Hallucination.