Adjective

(en adjective)

Of or pertaining to extension.

* {{quote-web

, date = 2011-07-20 , author = Edwin Mares , title = Propositional Functions , site = The Stanford Encyclopedia of Philosophy , url = http://plato.stanford.edu/archives/fall2011/entries/propositional-function , accessdate = 2012-07-15}}

     In both the intensional and extensional logic traditions, we see theories of complex terms. In the extensional tradition, disjunctive and conjunctive terms are interpreted by taking the union and intersection of classes. The conjunctive term AB'' is interpreted as the intersection of the class ''A'' and the class ''B'' and the extension of the disjunctive term ''A''+''B'' is understood as the union of the extensions of ''A'' and ''B''.
     In the intensional tradition, the reverse holds. The term ''AB'' is interpreted as the union of the properties in the intent of ''A'' and the intent of ''B'' and ''A''+''B'' is interpreted as the intersection of the properties in ''A'' and ''B . This reversal makes sense, since more things fit a smaller number of properties and fewer things fit a larger number of properties.

Having great extent.

Adjective

(en adjective)

Of or pertaining to intension.

* {{quote-web

, date = 2011-07-20 , author = Edwin Mares , title = Propositional Function , site = The Stanford Encyclopedia of Philosophy , url = http://plato.stanford.edu/archives/fall2011/entries/propositional-function/ , accessdate = 2012-07-15 }}

These two treatments of the predicate are typical of the two traditions in traditional logic—the intensional and the extensional traditions. Logicians who can be counted among the intensional logicians are Gottfried Leibniz, Johann Lambert, William Hamilton, Stanley Jevons, and Hugh MacColl. Among the extensional logicians are George Boole, Augustus De Morgan, Charles Peirce, and John Venn.