In linguistics

Linguistics

Linguistics is the scientific study of human language. Linguistics can be broadly broken into three categories or subfields of study: language form, language meaning, and language in context....

, logic

Logic

In philosophy, Logic is the formal systematic study of the principles of valid inference and correct reasoning. Logic is used in most intellectual activities, but is studied primarily in the disciplines of philosophy, mathematics, semantics, and computer science...

, philosophy

Philosophy

Philosophy is the study of general and fundamental problems, such as those connected with existence, knowledge, values, reason, mind, and language. Philosophy is distinguished from other ways of addressing such problems by its critical, generally systematic approach and its reliance on rational...

, and other fields, an intension is any property

Property (philosophy)

In modern philosophy, logic, and mathematics a property is an attribute of an object; a red object is said to have the property of redness. The property may be considered a form of object in its own right, able to possess other properties. A property however differs from individual objects in that...

 or quality

Quality (philosophy)

A quality is an attribute or a property. Attributes are ascribable, by a subject, whereas properties are possessible. In contemporary philosophy, the idea of qualities and especially how to distinguish certain kinds of qualities from one another remains controversial.-Background:Aristotle analyzed...

 connoted by a word

Word

In language, a word is the smallest free form that may be uttered in isolation with semantic or pragmatic content . This contrasts with a morpheme, which is the smallest unit of meaning but will not necessarily stand on its own...

, phrase

Phrase

In everyday speech, a phrase may refer to any group of words. In linguistics, a phrase is a group of words which form a constituent and so function as a single unit in the syntax of a sentence. A phrase is lower on the grammatical hierarchy than a clause....

 or other symbol. In the case of a word, it is often implied by the word's definition

Definition

A definition is a passage that explains the meaning of a term , or a type of thing. The term to be defined is the definiendum. A term may have many different senses or meanings...

. The term may also refer to all such intensions collectively, although the term comprehension

Comprehension (logic)

In logic, the comprehension of an object is the totality of intensions, that is, attributes, characters, marks, properties, or qualities, that the object possesses, or else the totality of intensions that are pertinent to the context of a given discussion...

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

Ferdinand de Saussure

Ferdinand de Saussure was a Swiss linguist whose ideas laid a foundation for many significant developments in linguistics in the 20th century. He is widely considered one of the fathers of 20th-century linguistics...

 contrasts three concepts:

• the signifier — the "sound image" or string of letters
  Letter (alphabet)
  A letter is a grapheme in an alphabetic system of writing, such as the Greek alphabet and its descendants. Letters compose phonemes and each phoneme represents a phone in the spoken form of the language....
  
   on a page that one recognizes as a sign
  Sign (linguistics)
  There are many models of the linguistic sign . A classic model is the one by the Swiss linguist Ferdinand de Saussure. According to him, language is made up of signs and every sign has two sides : the signifier , the "shape" of a word, its phonic component, i.e...
  
  .
• the signified — the concept
  Concept
  The word concept is used in ordinary language as well as in almost all academic disciplines. Particularly in philosophy, psychology and cognitive sciences the term is much used and much discussed. WordNet defines concept: "conception, construct ". However, the meaning of the term concept is much...
  
   or idea
  Idea
  In the most narrow sense, an idea is just whatever is before the mind when one thinks. Very often, ideas are construed as representational images; i.e. images of some object. In other contexts, ideas are taken to be concepts, although abstract concepts do not necessarily appear as images...
  
   that a sign evokes.
• the referent — the actual thing
  Object (philosophy)
  An object in philosophy is a technical term often used in contrast to the term subject. Consciousness is a state of cognition that includes the subject, which can never be doubted as only it can be the one who doubts, and some object or objects that may or may not have real existence without...
  
   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

Extension (semantics)

In any of several studies that treat the use of signs - for example, in linguistics, logic, mathematics, semantics, and semiotics - the extension of a concept, idea, or sign consists of the things to which it applies, in contrast with its comprehension or intension, which consists very roughly of...

. Without intension of some sort, words can have no meaning.

In philosophical arguments about dualism

Dualism

Dualism denotes a state of two parts. The term 'dualism' was originally coined to denote co-eternal binary opposition, a meaning that is preserved in metaphysical and philosophical duality discourse but has been diluted in general or common usages. Dualism can refer to moral dualism, Dualism (from...

 versus monism

Monism

Monism is any philosophical view which holds that there is unity in a given field of inquiry. Accordingly, some philosophers may hold that the universe is one rather than dualistic or pluralistic...

, it is noted that thoughts have intensionality and physical objects do not (S.E. Palmer, 1999), but rather have extension in space.

Intension and intensionality (the state of having intension) should not be confused with intention and intentionality

Intentionality

The term intentionality was introduced by Jeremy Bentham as a principle of utility in his doctrine of consciousness for the purpose of distinguishing acts that are intentional and acts that are not...

, 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.

See also

• Description logic
  Description logic
  Description logic is a family of formal knowledge representation languages. It is more expressive than propositional logic but has more efficient decision problems than first-order predicate logic....
  
  
• Intensional definition
  Intensional definition
  In logic and mathematics, an intensional definition gives the meaning of a term by specifying all the properties required to come to that definition, that is, the necessary and sufficient conditions for belonging to the set being defined....
  
  
• Intensional statement
  Intensional statement
  In logic, an intensional statement-form is a statement-form with at least one instance such that substituting co-extensive expressions into it does not always preserve logical value. An intensional statement is a statement that is an instance of an intensional statement-form. Here co-extensive...
  
  
• Intensional logic
  Intensional logic
  Intensional logic is an approach to predicate logic that extends first-order logic, which has quantifiers that range over the individuals of a universe , by additional quantifiers that range over terms that may have such individuals as their value...
  
  

External links

• Chalmers, David "On Sense and Intension".

• Rapaport, William J. "Intensionality v. Intentionality".