Version: v1, Published online: 1998
Retrieved March 24, 2019, from https://www.rep.routledge.com/articles/thematic/intensional-entities/v-1
Intensional entities are such things as concepts, propositions and properties. What makes them ‘intensional’ is that they violate the principle of extensionality; the principle that equivalence implies identity. For example, the concept of being a (well-formed) creature with a kidney and the concept of being a (well-formed) creature with a heart are equivalent in so far as they apply to the same things, but they are different concepts. Likewise, although the proposition that creatures with kidneys have kidneys and the proposition that creatures with hearts have kidneys are equivalent (both are true), they are not identical. Intensional entities are contrasted with extensional entities such as sets, which do satisfy the principle of extensionality. For example, the set of creatures with kidneys and the set of creatures with hearts are equivalent in so far as they have the same members and, accordingly, are identical. By this standard criterion, each of the following philosophically important types of entity is intensional: qualities, attributes, properties, relations, conditions, states, concepts, ideas, notions, propositions and thoughts.
All (or most) of these intensional entities have been classified at one time or another as kinds of universals. Accordingly, standard traditional views about the ontological status of universals carry over to intensional entities. Nominalists hold that they do not really exist. Conceptualists accept their existence but deem it to be mind-dependent. Realists hold that they are mind-independent. Ante rem realists hold that they exist independently of being true of anything; in re realists require that they be true of something.
Bealer, George. Intensional entities, 1998, doi:10.4324/9780415249126-X019-1. Routledge Encyclopedia of Philosophy, Taylor and Francis, https://www.rep.routledge.com/articles/thematic/intensional-entities/v-1.
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