Extensional context

Extensional context

In philosophy of language, a context in which a sub-sentential expression "e" appears is called extensional if and only if "e" can be replaced by an expression with the same extension and necessarily preserve truth-value. The extension of a term is the set of objects that that term denotes.

Take the case of Clark Kent, who is Superman. Suppose that Lois Lane fell out of a window and Superman caught her. Thus the statement, "Clark Kent caught Lois Lane," is true because it has an extensional context. The names "Superman" and "Clark Kent" have the same extension, which is to say that they both refer to the same person, i.e. that superhero who is vulnerable to kryptonite. Anybody that Superman caught, Clark Kent caught.

In opposition to extensional contexts are intensional contexts, where synonymous terms cannot be substituted in without potentially compromising the truth-value.

Suppose that Lois Lane believes that Clark Kent will investigate a news story with her. The statement, "Lois Lane believes that Superman will investigate a news story with her," is false, even though Superman is Clark Kent. This is because 'believes' is typically an intensional context.

Intensional Logic

Intensional logic is logic that is not truth-functional. Examples are temporal logic, modal logic, deontic logic, probabilistic logic and epistemic logic.

ee also

* Extension (semantics)
* Extension (predicate logic)
* Extensional definition


Wikimedia Foundation. 2010.

Игры ⚽ Поможем решить контрольную работу

Look at other dictionaries:

  • Extensional definition — An extensional definition of a concept or term formulates its meaning by specifying its extension, that is, every object that falls under the definition of the concept or term in question.For example, an extensional definition of the term nation… …   Wikipedia

  • David Kaplan (philosopher) — For other people of the same name, see David Kaplan (disambiguation). David Benjamin Kaplan (born 1933) is an American philosopher and logician teaching at UCLA. His philosophical work focuses on logic, philosophical logic, modality, philosophy… …   Wikipedia

  • extension/intension — The extension of a predicate is the class of objects that it describes: the extension of ‘red’ is the class of red things. The intension is the principle under which it picks them out, or in other words the condition a thing must satisfy to be… …   Philosophy dictionary

  • Intuitionistic type theory — Intuitionistic type theory, or constructive type theory, or Martin Löf type theory or just Type Theory is a logical system and a set theory based on the principles of mathematical constructivism. Intuitionistic type theory was introduced by Per… …   Wikipedia

  • solids, mechanics of — ▪ physics Introduction       science concerned with the stressing (stress), deformation (deformation and flow), and failure of solid materials and structures.       What, then, is a solid? Any material, fluid or solid, can support normal forces.… …   Universalium

  • Asia — /ay zheuh, ay sheuh/, n. a continent bounded by Europe and the Arctic, Pacific, and Indian oceans. 2,896,700,000; ab. 16,000,000 sq. mi. (41,440,000 sq. km). * * * I Largest continent on Earth. It is bounded by the Arctic Ocean, the Pacific Ocean …   Universalium

  • logic, history of — Introduction       the history of the discipline from its origins among the ancient Greeks to the present time. Origins of logic in the West Precursors of ancient logic       There was a medieval tradition according to which the Greek philosopher …   Universalium

  • Implementation of mathematics in set theory — This article examines the implementation of mathematical concepts in set theory. The implementation of a number of basic mathematical concepts is carried out in parallel in ZFC (the dominant set theory) and in NFU, the version of Quine s New… …   Wikipedia

  • Logicism — is one of the schools of thought in the philosophy of mathematics, putting forth the theory that mathematics is an extension of logic and therefore some or all mathematics is reducible to logic.[1] Bertrand Russell and Alfred North Whitehead… …   Wikipedia

  • plate tectonics — plate tectonic, adj. Geol. a theory of global tectonics in which the lithosphere is divided into a number of crustal plates, each of which moves on the plastic asthenosphere more or less independently to collide with, slide under, or move past… …   Universalium

Share the article and excerpts

Direct link
… Do a right-click on the link above
and select “Copy Link”