An important historical branch designation rather than a current one, natural philosophy was the study of nature and the physical universe by philosophical (that is, largely empirical reason-based) methods.

Metaphysics is the philosophical investigation of reality, including the nature of the world and the entities it contains. While such an investigation inevitably overlaps with natural philosophy—the sciences, especially physics…

Political philosophy is at least as old as Plato (428/227 or 424/423-348/347 BC) and is concerned with the nature of the state and, more broadly, with coercive institutions, and their…