Editing Sense and reference (section)

==Sense==
[[File:Mengs, Hesperus als Personifikation des Abends.jpg|thumb|right|160px|[[Hesperus]]]]
[[File:Jean-Marc Nattier, The Countess de Brac as Aurora (1741).jpg|thumb|right|140px|[[Phosphorus (morning star)|Phosphorus]]]] 
Frege introduced the notion of "sense" (German: ''Sinn'') to accommodate difficulties in his early theory of meaning.<ref>[[Barbara Cassin|Cassin, B.]], Apter, E., Lezra, J., & [[Michael Wood (academic)|Wood, M.]], eds., ''Dictionary of Untranslatables: A Philosophical Lexicon'' ([[Princeton, New Jersey|Princeton]]: [[Princeton University Press]], 2014), [https://books.google.com/books?id=UXP5AQAAQBAJ&pg=PA965&redir_esc=y#v=onepage&q&f=false p. 965].</ref>{{rp|965}}

First, if the entire significance of a sentence consists of its truth value, it follows that the sentence will have the same significance if we replace a word of the sentence with one having an identical reference, as this will not change its truth value.<ref name="On Sense and Reference, p. 32">"On Sense and Reference", p. 32.</ref> The reference of the whole is determined by the reference of the parts. If ''the evening star'' has the same reference as ''the morning star'', it follows that ''the evening star is a body illuminated by the Sun'' has the same truth value as ''the morning star is a body illuminated by the Sun''. But it is possible for someone to think that the first sentence is true while also thinking that the second is false. Therefore, the thought corresponding to each sentence cannot be its reference, but something else, which Frege called its ''sense''.

Second, sentences that contain proper names with no reference cannot have a truth value at all. Yet the sentence 'Odysseus was set ashore at [[Homer's Ithaca|Ithaca]] while sound asleep' obviously has a sense, even though 'Odysseus' has no reference. The thought remains the same whether or not 'Odysseus' has a reference.<ref name="On Sense and Reference, p. 32"/> Furthermore, a thought cannot contain the objects that it is about. For example, [[Mont Blanc]], 'with its snowfields', cannot be a component of the thought that Mont Blanc is more than 4,000 metres high. Nor can a thought about [[Mount Etna|Etna]] contain lumps of solidified lava.<ref>See Frege's undated letter to [[Philip Jourdain]], published in ''Frege's Philosophical and Mathematical Correspondence'', ed. Gottfried Gabriel, Hans Hermes, Friedrich Kanbartel, Christian Thiel and Albet Veraart, transl. Hans Kaal, Oxford: Blackwell 1980. (See also Frege's letter to Russell dated 1904, in the same collection.)</ref>

Frege's notion of sense is somewhat obscure, and neo-Fregeans have come up with different candidates for its role.<ref>Cumming, S., [https://plato.stanford.edu/entries/names/ Entry on Names], ''[[Stanford Encyclopedia of Philosophy]]'', 2013.</ref> Accounts based on the work of [[Rudolf Carnap|Carnap]]<ref>''[[Meaning and Necessity]]'', Chicago: University of Chicago Press, 1947.</ref> and [[Alonzo Church|Church]]<ref>“A Formulation of the Logic of Sense and Denotation”, in P. Henle, M. Kallen, and S. K. Langer, eds., ''Structure, Method, and Meaning'', New York: Liberal Arts Press, 1951</ref> treat sense as an [[intension]], or a function from [[possible world]]s to [[Extension (semantics)|extensions]]. For example, the intension of ‘number of planets’ is a function that maps any possible world to the number of planets in that world. [[John McDowell]] supplies cognitive and reference-determining roles.<ref>McDowell, J., [https://books.google.com/books?id=4CZ1zeQAFT8C&pg=PA171&redir_esc=y#v=onepage&q&f=false “On the Sense and Reference of a Proper Name”], [[Mind (journal)|''Mind'']], 86: 159–85, 1977.</ref> [[Michael Devitt]] treats senses as causal-historical chains connecting names to referents, allowing that repeated "groundings" in an object account for reference change.<ref>Devitt, M., ''Designation'', New York: Columbia University Press, 1981.</ref>