Mereology is the philosophy of parts and wholes.
Part of ontology. Mereology is partly concerned with answering the Special Composition Question, which is: “When do two or more things become something else?” Mereological universalism answers that any combination of things across space or time constitutes a new thing regardless of sensibility. Regards it arbitrary to accept some composites as things while not others—that discernment, on the flipside, is eliminitivism. Mereological nihilism rejects these distinctions and postulates that only simples physically exist in reality.rV1