Duality may refer to: In philosophy, logic, and psychology: Dualism, a twofold division in several spiritual, religious, and philosophical doctrines Dualism (philosophy of mind), where the body and mind are considered to be irreducibly distinct De Morgan's Laws, specifically the ability to generate the dual of any logical expression. In mathematics: Duality (mathematics), a mathematical concept Dual (category theory), a formalization of mathematical duality Duality (projective geometry),… (More on Duality)