The Problem of Perception is a pervasive and traditional problem about our ordinary conception of perceptual experience. The problem is created by the phenomena of perceptual illusion and hallucination: if these kinds of error are possible, how can perceptual experience be what we ordinarily understand it to be: something that enables direct perception of the world? These possibilities of error challenge the intelligibility of our ordinary conception of perceptual experience; the major theories of experience are responses to this challenge.