|Morning Star/Evening Star: Example for intensions from Frege's Über Sinn und Bedeutung (1982). The extension would be the planet Venus. Intensions may cause difficulties in relation to so called opaque contexts. E.g. a whitness maintains that she has seen the morning star. She may then not be quoted as having seen the evening star - while both are identical to the Venus. See also opacity, identity, intensions.|
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|Danto I 129
Morning Star/Evening Star/Danto: the example shows that meaning is not the same as reference - otherwise knowledge about identity was no genuine knowledge.
A. C. Danto
The Philosophical Disenfranchisement of Art (Columbia Classics in Philosophy) New York 2005