Relativism has been, in its various guises, both one of the most popular and most reviled philosophical doctrines of our time. Defenders see it as a harbinger of tolerance and the only ethical and epistemic stance worthy of the open-minded and tolerant. Detractors dismiss it for its alleged incoherence and uncritical intellectual permissiveness. Debates about relativism permeate the whole spectrum of philosophical sub-disciplines. From ethics to epistemology, science to religion, political theory to ontology, theories of meaning and even logic, philosophy has felt the need to respond to this heady and seemingly subversive idea. Discussions of relativism often also invoke considerations relevant to the very nature and methodology of philosophy and to the division between the so-called “analytic and continental” camps in philosophy. And yet, despite a long history of debate going back to Plato and an increasingly large body of writing, it is still difficult to come to an agreed definition of what, at its core, relativism is, and what philosophical import it has. This entry attempts to provide a broad account of the many ways in which “relativism” has been defined, explained, defended and criticized.