Pluralism is a term used in philosophy, meaning "doctrine of multiplicity," often used in opposition to monism ("doctrine of unity") and dualism ("doctrine of duality"). The term has different meanings in metaphysics, ontology, epistemology and logic.

In metaphysics, pluralism is the doctrine that contradicts the assertions of monism and dualism, and claims that there are in fact many different substances in nature that constitute reality.

In ontology, pluralism refers to different ways, kinds, or modes of being. For example, a topic in ontological pluralism is the comparison of the modes of existence of things like 'humans' and 'cars' with things like 'numbers' and some other concepts as they are used in science.

In epistemology, pluralism is the position that there is not one consistent means of approaching truths about the world, but rather many. Often this is associated with pragmatism, or conceptual, contextual, or cultural relativism. In the philosophy of science it may refer to the acceptance of co-existing scientific paradigms which though accurately describing their relevant domains are nonetheless incommensurable.

In logic, pluralism is the view that there is no one correct logic, or alternatively, that there is more than one correct logic. One may, for instance, believe that classical logic is the correct logic generally, but believe that paraconsistent logic is the correct logic for dealing with certain paradoxes. However, there are different versions of logical pluralism depending on what one believes 'logic' to be and what it means for a logical system to be 'correct'.