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Extensionalism
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<h2 id="concept">Concept</h2> <p>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. <a href="/facts/Rudolf_Carnap/0nqgBwnw">Rudolf Carnap</a> (in his earlier work) and <a href="/facts/Willard_Van_Orman_Quine/2RrhATxa">Willard Van Orman Quine</a> were prominent proponents of this view. </p><p>Carnap's thesis of extensionality is associated with the relation between extensional and nonextensional languages.<a class="footnote-ref" id="fnref:2" href="#fn:2"><sup>2</sup></a> 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.<a class="footnote-ref" id="fnref:3" href="#fn:3"><sup>3</sup></a> The idea put forward by <a href="/facts/Richard_Montague/oaBs5m51">Richard Montague</a> that the intension of a predicate or a sentence is identifiable from possible worlds to extensions is also attributed to Carnap.<a class="footnote-ref" id="fnref:4" href="#fn:4"><sup>4</sup></a> </p><p>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.<a class="footnote-ref" id="fnref:5" href="#fn:5"><sup>5</sup></a> The early philosophy of <a href="/facts/Ludwig_Wittgenstein/wN9bAgMz">Ludwig Wittgenstein</a> also provided an important argument for extensionalism when he said that "a proposition is a truth-function of elementary propositions".<a class="footnote-ref" id="fnref:6" href="#fn:6"><sup>6</sup></a> </p> <h2 id="see-also">See also</h2> <ul><li><a href="/facts/Extension_(semantics)/MykUsmvj">Extension (semantics)</a></li> <li><a href="/facts/Extension_(predicate_logic)/ruBkmsJ6">Extension (predicate logic)</a></li></ul> <ul><li>Carnap, Rudolf: <i>Der logische Aufbau der Welt</i>. Berlin-Schlachtensee 1928. Neuauflage Hamburg 1998.</li> <li>Carnap, Rudolf: <i>Logische Syntax der Sprache.</i> Vienna 1934.</li> <li>Carnap, Rudolf: <i>Bedeutung und Notwendigkeit. Eine Studie zur Semantik und modalen Logik</i>. Wien/New York 1972 (Originalausgabe: <i>Meaning and Necessity. A Study in Semantics and Modal Logic</i>. Chicago/Toronto/London 1947).</li> <li>Quine, Willard Van Orman: "Three Grades of Modal Involvement", in: <i>Proceedings of the 11th International Congress of Philosophy</i>, Vol. 14. Amsterdam 1953, 65–81.</li> <li>Quine, Willard Van Orman: "Reference and Modality", in: <i>From a Logical Point of View</i>. Cambridge (Massachusetts) 1953.</li> <li>Quine, Willard Van Orman: <i>Word and Object</i>. Cambridge (Massachusetts) 1960.</li> <li>Quine, Willard Van Orman: <i>Confessions of a Confirmed Extensionalist</i>. Cambridge (Massachusetts) 2008.</li></ul> <h2 id="references">References</h2> <ol> <li id="fn:1"><p>Ranganathan, Shyam (2007). Ethics and the History of Indian Philosophy. Delhi: Motilal Banarsidass Publishers. p. 94. ISBN 978-81-208-3193-3. <a href="978-81-208-3193-3" target="_blank">978-81-208-3193-3</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li> <li id="fn:2"><p>Wilson, Robert Andrew; Keil, Frank C. (2001). The MIT Encyclopedia of the Cognitive Sciences. Cambridge, MA: MIT Press. p. 306. ISBN 0-262-73144-4. <a href="0-262-73144-4" target="_blank">0-262-73144-4</a> <a href="#fnref:2" class="footnote-back-ref">↩</a></p></li> <li id="fn:3"><p>Wilson, Robert Andrew; Keil, Frank C. (2001). The MIT Encyclopedia of the Cognitive Sciences. Cambridge, MA: MIT Press. p. 306. ISBN 0-262-73144-4. <a href="0-262-73144-4" target="_blank">0-262-73144-4</a> <a href="#fnref:3" class="footnote-back-ref">↩</a></p></li> <li id="fn:4"><p>Bonk, Thomas (2003). Language, Truth and Knowledge: Contributions to the Philosophy of Rudolf Carnap. Dordrecht: Springer Science & Business Media. p. 11. ISBN 1-4020-1206-3. <a href="1-4020-1206-3" target="_blank">1-4020-1206-3</a> <a href="#fnref:4" class="footnote-back-ref">↩</a></p></li> <li id="fn:5"><p>Hylton, Peter (2007). Quine. New York, NY: Routledge. p. 289. ISBN 978-0-203-96243-5. <a href="978-0-203-96243-5" target="_blank">978-0-203-96243-5</a> <a href="#fnref:5" class="footnote-back-ref">↩</a></p></li> <li id="fn:6"><p>Wilson, Robert Andrew; Keil, Frank C. (2001). The MIT Encyclopedia of the Cognitive Sciences. Cambridge, MA: MIT Press. p. 306. ISBN 0-262-73144-4. <a href="0-262-73144-4" target="_blank">0-262-73144-4</a> <a href="#fnref:6" class="footnote-back-ref">↩</a></p></li> </ol>