Extensionalism, in the

philosophy of language In analytic philosophy, philosophy of language investigates the nature of language and the relations between language, language users, and the world. Investigations may include inquiry into the nature of meaning, intentionality, reference, ...

, in

logic Logic is the study of correct reasoning. It includes both formal and informal logic. Formal logic is the science of deductively valid inferences or of logical truths. It is a formal science investigating how conclusions follow from premises ...

and

semantics Semantics (from grc, σημαντικός ''sēmantikós'', "significant") is the study of reference, meaning, or truth. The term can be used to refer to subfields of several distinct disciplines, including philosophy Philosophy (f ...

, is the view that all languages or at least all scientific languages should be

extensional In any of several fields of study that treat the use of signs — for example, in linguistics Linguistics is the science, scientific study of human language. It is called a scientific study because it entails a comprehensive, systematic, obj ...

. It has been described as the default option for the scientism in the nineteenth century and the result of the application of empiricistic inductive methodology to the problem of semantics.

Concept

The idea of extensionality is considered a form of reductionism with the way it holds that every meaningful and declarative sentence is equivalent to some extensional sentence.

Rudolf Carnap Rudolf Carnap (; ; 18 May 1891 – 14 September 1970) was a German-language philosopher who was active in Europe before 1935 and in the United States thereafter. He was a major member of the Vienna Circle and an advocate of logical positivism. He ...

(in his earlier work) and

Willard Van Orman Quine Willard Van Orman Quine (; known to his friends as "Van"; June 25, 1908 – December 25, 2000) was an American philosopher and logician in the analytic tradition, recognized as "one of the most influential philosophers of the twentieth century". ...

were prominent proponents of this view. Carnap's thesis of extensionality is associated with the relation between extensional and nonextensional languages. According to the thinker, the former has simpler structures and constitutive rules than the latter so that it is possible to discuss exhaustively all scientific phenomena when using extensional language. The idea put forward by

Richard Montague Richard Merritt Montague (September 20, 1930 – March 7, 1971) was an American mathematician and philosopher who made contributions to mathematical logic and the philosophy of language. He is known for proposing Montague grammar to formalize th ...

that the intension of a predicate or a sentence is identifiable from possible worlds to extensions is also attributed to Carnap. Quine, who maintained that he is a "confirmed extensionalist" maintained that an extensional language is one that contains no expressions that lead to non-extensionaal contexts. The early philosophy of

Ludwig Wittgenstein Ludwig Josef Johann Wittgenstein ( ; ; 26 April 1889 – 29 April 1951) was an Austrian-British philosopher who worked primarily in logic, the philosophy of mathematics, the philosophy of mind, and the philosophy of language. He is considere ...

also provided an important argument for extensionalism when he said that "a proposition is a truth-function of elementary propositions".

References

{{Reflist *Carnap, Rudolf: ''Der logische Aufbau der Welt''. Berlin-Schlachtensee 1928. Neuauflage Hamburg 1998. *Carnap, Rudolf: ''Logische Syntax der Sprache.'' Vienna 1934. *Carnap, Rudolf: ''Bedeutung und Notwendigkeit. Eine Studie zur Semantik und modalen Logik''. Wien/New York 1972 (Originalausgabe: ''Meaning and Necessity. A Study in Semantics and Modal Logic''. Chicago/Toronto/London 1947). *Quine, Willard Van Orman: "Three Grades of Modal Involvement", in: ''Proceedings of the 11th International Congress of Philosophy'', Vol. 14. Amsterdam 1953, 65–81. *Quine, Willard Van Orman: "Reference and Modality", in: ''From a Logical Point of View''. Cambridge (Massachusetts) 1953. *Quine, Willard Van Orman: ''Word and Object''. Cambridge (Massachusetts) 1960. *Quine, Willard Van Orman: ''Confessions of a Confirmed Extensionalist''. Cambridge (Massachusetts) 2008. Philosophy of language Logic philo-stub

Concept

See also

References