For alternative meanings see definition (disambiguation)

A definition may be a statement of the essential properties of a certain thing, or a statement of equivalence between a term and that term's meaning. The two are not mutually exclusive, nor are they equivalent.

A number of different kinds and techniques of definition can be distinguished, including:

• dictionary or lexical definition
• intensional definition
• extensional definition
• ostensive definition
• operational definition
• theoretical definition
• definition by genus and difference
• circular definition
• recursive definition
• stipulative definition
• precising definition
• persuasive definition

Contents

1 Determining meaning: extension, intension, ambiguity, and vagueness 2 A definition of 'definition' 3 Quote 4 See also 5 External links

Determining meaning: extension, intension, ambiguity, and vagueness

Just as arguments can be good or bad, definitions can be good or bad. A definition gives us the meaning of a word. To understand this more deeply requires an elucidation of a few features of meaning, the principal ones being extension, intension, ambiguity, and vagueness.

The distinction between the extension and the intension of a word is very similar to the distinction between a word's denotation and connotation. For example, the extension of the word "bachelor" would be all and only the bachelors in the world. The extension of this word would include several hundreds of millions of men. The intension of the word is more brief because it includes just two properties: the property of being a man, and the property of being unmarried. Basically, all bachelors are unmarried men, and only bachelors are unmarried men.

The sort of definition that philosophers are interested in, insofar as they are interested in definitions at all, is one that identifies a word's intension, rather than its extension. A definition of the word 'bachelor' is 'unmarried man'. Aside from being practically impossible, such a list is not what is generally desired. What is desired is a description of what all those things we call 'bachelors' have in common that distinguishes them from all non-bachelors. A list of all bachelors would be static, and could not expand to determine whether any new human is a bachelor or not.

There are two different ways in which the meanings of words can be unclear. Words can be unclear in the sense of being ambiguous, of being vague, or a combination of the two. Most words are, in fact, both ambiguous and vague. This is not a skeptical or even a controversial claim; to say that many, or perhaps even most, words are both ambiguous and vague is not to say that they have no meaning. It is to say, first, that many individual words have many distinct senses; and, second, that those senses are often, in ordinary language, not meant to be exhaustively precise. A word that is both ambiguous and vague, whose extreme limits are fuzzy and undefined, can still contain a rich fund of meaning.

A definition of 'definition'

Suppose we have decided to define certain word or concept associated with that word. Suppose also that we have identified which sense of the word we are interested in, and we have noted clear cases, some unclear cases, and some borderline cases of the application of the word. The question then is: how can this word be defined? What is desired here is a description of the intension of the word: that is, an account of the set of properties that characterizes all and only members of the extension. In that case, it seems the following is a serviceable account of the meaning of '(intensional) definition':

The definition of a concept, or of (a given sense of) a word or phrase, is a description of its intension--that is, the set of properties that characterizes all and only members of the extension of the word; the extension is all the things that the concept, word, or phrase applies to.

Some philosophers have criticisms of this sort of definition of the word 'definition'; or perhaps it would be better to say that some philosophers think that it is, for various reasons, impossible to give exhaustively exact definitions of most concepts, words, and phrases. Two prominent critics are Wittgenstein and Quine. Still most philosophers still acknowledge that in philosophy something similar to giving definitions of important philosophical concepts is necessary.

Quote

Nothing is more usual than for philosophers to encroach on the province of grammarians, and to engage in disputes of words, while they imagine they are handling controversies of the deepest importance and concern. — David Hume

See also

• fallacies of definition
• Ramsey-Lewis method
• analytic proposition
• synthetic proposition

External links

• The structure and internal logic of definitions (http://samvak.tripod.com/define.html)

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