Intension

: "Not to be confused with the homophone intention; or the related concept of intentionality. For the song "Intension" by Tool, see "10,000 Days"."

Intension refers to the set of all "possible" things a word or phrase "could" describe. It stands in contradistinction to extension (or "denotation"), which refers to the set of all "actual" things the word describes. For example, the intension of a car is the all-inclusive concept of a car, including, for example, mile-long cars made of chocolate that may not actually exist. But the extension of 'car' is all actual instances of cars (past, present, and future), which will amount to millions or billions of cars, but probably does not include any mile-long cars made of chocolate.

In linguistics, logic, philosophy, and other fields, an intension is any property or quality connoted by a word, phrase or other symbol. In the case of a word, it is often implied by its definition. The term may also refer to the complete set of meanings or properties that are implied by a concept, although the term "comprehension" is technically more correct for this.

The meaning of a word can be thought of as the bond between "the idea or thing the word refers to" and "the word itself". Swiss linguist Ferdinand de Saussure contrasts three concepts:
*the "signified" — the concept or idea that a sign evokes.
*the "signifier" — the "sound image" or string of letters on a page that one recognizes as a sign.
*the "referent" — the actual thing or set of things a sign refers to. See "Dyadic signs" and "Reference (semantics)".

Intension is analogous to the signified, extension to the referent. The intension thus links the signifier to the sign's extension. Without intension of some sort, words can have no meaning.

In philosophical arguments about dualism versus monism, it is noted that thoughts have intensionality and physical objects do not (S.E. Palmer, 1999)

"Intension" and "intensionality" (the state of having intension) should not be confused with "intention" and "intentionality", which are pronounced the same and occasionally arise in the same philosophical context. Where this happens, the letter 's' or 't' is sometimes italicized to emphasize the distinction.

ee also

* Comprehension
* Description Logic
* Intensional definition
* Intensional statement
* Intensional logic

References

* Ferdinand De Saussure: "Course in General Linguistics". Open Court Classics, July 1986. ISBN 0-812-69023-0
**S. E. Palmer, Vision Science: From Photons to Phenomenology, 1999. MIT Press, ISBN 78-0262161831