Five Types of Definitions

by Richard W. Hartzell   

One's understanding of the meaning of various terminology is greatly facilitated if an appropriate type of definition is used. At least five types of definitions are relevant to the discussion of Taiwan status issues.

Lexical definitions attempt to report usage. All good dictionary definitions are lexical, since they state how native speakers employ the words in all of their various senses.

Stipulative definitions are those which specify or stipulate the meaning of a word or phrase. Sometimes these involve the introduction of new terms, or the stipulation of new meaning for old terms.

Extensional definitions are simply a list of all the things to which the term applies. For example, the term "Chinese Provincial Capital" can be defined extensionally by listing all the capitals of the Chinese provinces.

Intensional definitions list a set of properties such that the term applies to all things having that set of properties, and to nothing else. A chemist or geologist might supply us with an intentional definition of the term "gold".

Ostensive definitions indicate the meaning of a term by providing a sample of the things denoted. We can define "polite" ostensively by making a listing of polite actions and behavior.

Notes: Obviously, ostensive definitions are risky, or unclear, in ways that extensional definitions are not. An extensional definition provides the complete extension of a term or concept, and hence leaves minimal margin for error in interpretation. An ostensive definition furnishes only part of the extension of a term. However, some concepts are so complex that extensional definitions are extremely difficult to formulate.