====== Extension (logic) ======

Refers to the totality of all objects described by a particular term.

For example, the //extension// of the term "horse" could be defined as follows:

> "Horse" describes all animals of the genus [[wp>Equidae]].

In other contexts, the same term may have a different extension:

> The term "horse" describes all the chess pieces also known as "[[wp>Knight (chess)|knights]]".

The opposite term to //extension// is [[glossary:intension|intension]], which describes the definition of a term by its associated meanings.

===== Significance =====
==== Equivocation ====

As the examples above show, the same identifier can describe different sets of terms depending on the context. It is therefore generally important to understand the precise //extension// of a term in order to avoid possible errors of equivocation.

==== Amphiboly ====

Ambiguity of the extension of a term can also result from the grammatical structure of a statement (<span maniculus "see:">[[glossary:equivocation:amphiboly|amphiboly]]</span>). See also: [[logic:emergence:ambiguity:syntactic_ambiguity|Syntactic ambiguity]].

==== See also ====

  * [[glossary:intension|Intension]]

  * [[glossary:equivocation:amphiboly|Amphiboly]]
  * [[glossary:equivocation:index|Equivocation]]
  * [[logic:emergence:ambiguity:syntactic_ambiguity|Syntactic ambiguity]]

==== More information ====

  * [[wp>Extensional and intensional definitions]] on //Wikipedia//

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