|Unicorn example, philosophy: the problem is about linguistic expressions for non-existent objects and principles of using these expressions. In logic it comes to the question of whether sentences containing expressions for non-existent objects are true, false, or senseless. See also Pegasus, nonexistence, reference, truth value, truth conditions, assertibility, meaning, sense, truth value gap.|
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|II 47Frege: Unicorn: sentence without truth value, predicates can not be denied nor attrributed - thought the same, whether reference ("importance") or not.
The fact that a particular name has no support in the form of an external object, has no consequences for the belonging of the name to the language.
Die Grundlagen der Arithmetik Stuttgart 1987
Funktion, Begriff, Bedeutung Göttingen 1994
Logische Untersuchungen Göttingen 1993