A Unified Review of Shadows, Darkness, and Light under a Privation Model

This paper proposes a privation-based account of darkness, light, and shadow. Darkness is treated as the default state rather than a positive entity, light as an operation that removes darkness, and shadow as the residual of incomplete removal. On this basis, the paper distinguishes shadows from mere absences of light and argues that apparent motion of shadows reflects changes in illumination conditions rather than the movement of any entity. Using this framework, it clarifies why shadows exhibit relational and contrast-dependent properties and why their apparent speed cannot exceed the speed of light in terms of causality or information transfer. The account integrates metaphysical notions of privation with standard results from geometric optics and contemporary discussions of shadow motion.