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DOI: 10.4324/9780415249126-Y057-1
Version: v1,  Published online: 1998
Retrieved July 10, 2020, from

Article Summary

A definition is a statement, declaration or proposal establishing the meaning of an expression. In virtue of the definition, the expression being defined (the ‘definiendum’) is to acquire the same meaning as the expression in terms of which it is defined (the ‘definiens’). For example, ‘Man is a rational animal’ determines the meaning of the term ‘man’ by making it synonymous with ‘rational animal’. Classical theory maintains that a good definition captures the ‘real nature’ of what is defined: ‘A ‘‘definition’’ is a phrase signifying a thing’s essence’ (Aristotle). Historically, philosophers have come to distinguish these ‘real’ definitions from ‘nominal’ definitions that specify the meaning of a linguistic expression rather than signify the essential nature of an object, ‘making another understand by Words, what Idea, the term defined stands for’ (Locke).

A further distinction can be drawn between contextual or implicit definitions, on the one hand, and explicit definitions, on the other. Often a definition fixes meaning directly and explicitly: for example, the definition of a proper name might well take the form of an explicit identity statement (‘Pegasus = the winged horse’) and a definition of a predicate is usually given (or can be re-cast) in the form of an equivalence (‘For every x: x is a man if and only if x is a rational animal’). But sometimes the meaning of a term is specified in context, by way of the meaning of larger expressions in which the term occurs. A paradigmatic example of this is Bertrand Russell’s analysis of the meaning of the definite article.

Citing this article:
Antonelli, G. Aldo. Definition, 1998, doi:10.4324/9780415249126-Y057-1. Routledge Encyclopedia of Philosophy, Taylor and Francis,
Copyright © 1998-2020 Routledge.

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