Pluralism (philosophy)

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, and epistemology.

In metaphysics, pluralism is a doctrine that there is more than one reality, while realism holds that there is but one reality, that may have single objective ontology or plural ontology. In one form, it is a doctrine that many substances exist, in contrast with monism which holds existence to be a single substance, often either matter (materialism) or mind (idealism), and dualism believes two substances, such as matter and mind, to be necessary.

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.

Metaphysical pluralism
Metaphysical pluralism in philosophy is the multiplicity of metaphysical models of the structure and content of reality, both as it appears and as logic dictates that it might be, as is exhibited by the four related models in Plato's Republic and as developed in the contrast between phenomenalism and physicalism. Pluralism is in contrast to the concept of monism in metaphysics, while dualism is a limited form, a pluralism of exactly two models, structures, elements, or concepts. A distinction is made between the metaphysical identification of realms of reality and the more restricted sub-fields of ontological pluralism (that examines what exists in each of these realms) and epistemological pluralism (that deals with the methodology for establishing knowledge about these realms).

Ancient pluralism
The concept of elements in the Western tradition originates from Babylonian mythology. The Enûma Eliš, a text written between the 18th and 16th centuries BC, describes four cosmic elements: the sea, earth, sky, and wind. In Greece, Empedocles wrote that they were fire, air, water and earth, although he used the word "root" rather than "element" (στοιχεῖον; stoicheion), which appeared later in Plato. From the association (φιλία; philia) and separation (νεῖκος; neikos) of these indestructible and unchangeable root elements, all things came to be in a fullness (πλήρωμα; pleroma) of ratio (λόγος; logos) and proportion (ἀνάλογος; analogos).

Aristotle incorporated these elements, but his substance pluralism was not material in essence. His hylomorphic theory allowed him to maintain a reduced set of basic material elements as per the Milesians, while answering for the ever-changing flux of Heraclitus and the unchanging unity of Parmenides. In his Physics, due to the continuum of Zeno's paradoxes, as well as both logical and empirical considerations for natural science, he presented numerous arguments against the atomism of Leucippus and Democritus, who posited a basic duality of void and atoms. The atoms were an infinite variety of irreducibles, of all shapes and sizes, which randomly collide and mechanically hook together in the void, thus providing a reductive account of changeable figure, order and position as aggregates of the unchangeable atoms.

Ontological pluralism
The topic of ontological pluralism discusses different ways, kinds, or modes of being. Turner suggests that "In contemporary guise, it is the doctrine that a logically perspicuous description of reality will use multiple quantifiers which cannot be thought of as ranging over a single domain." "There are numbers, fictional characters, impossible things, and holes. But, we don’t think these things all exist in the same sense as cars and human beings."

It is common to refer to a film, novel or otherwise fictitious or virtual narrative as not being 'real'. Thus, the characters in the film or novel are not real, where the 'real world' is the everyday world in which we live. However, as authors are wont to say, fiction informs our concept of reality, and so has some kind of reality.

Ludwig Wittgenstein's notion of language-games argues that there is no over-arching, single, fundamental ontology, but only a patchwork of overlapping interconnected ontologies ineluctably leading from one to another. For example, Wittgenstein discusses 'number' as technical vocabulary and in more general usage: ""“All right: the concept of 'number' is defined for you as the logical sum of these individual interrelated concepts: cardinal numbers, rational numbers, real numbers etc.;” ... — it need not be so. For I can give the concept 'number' rigid limits in this way, that is, use the word 'number' for a rigidly limited concept, but I can also use it so that the extension of the concept is not closed by a frontier. ...Can you give the boundary? No. You can draw one...""

- Ludwig Wittgenstein

Wittgenstein suggests that it is not possible to identify a single concept underlying all versions of 'number', but that there are many interconnected meanings that transition one to another; vocabulary need not be restricted to technical meanings to be useful, and indeed technical meanings are 'exact' only within some proscribed context:

Eklund has argued that Wittgenstein's conception includes as a special case the technically constructed, largely autonomous, forms of language or linguistic frameworks of Carnap and Carnapian ontological pluralism. He places Carnap's ontological pluralism in the context of other philosophers, such as Eli Hirsch and Hilary Putnam

Epistemological pluralism
Epistemological pluralism is a term used in philosophy and in other fields of study to refer to different ways of knowing things, different epistemological methodologies for attaining a full description of a particular field. In the philosophy of science epistemological pluralism arose in opposition to reductionism to express the contrary view that at least some natural phenomena cannot be fully explained by a single theory or fully investigated using a single approach.