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In logic, a slingshot argument is one of a group of arguments claiming to show that all true sentences stand for the same thing. This type of argument was dubbed the "slingshot" by philosophers Jon Barwise and John Perry (1981) due to its disarming simplicity. It is usually said that versions of the slingshot argument have been given by Gottlob Frege, Alonzo Church, W. V. Quine, and Donald Davidson. However, it has been disputed by Lorenz Krüger (1995) that there is much unity in this tradition. Moreover, Krüger rejects Davidson's claim that the argument can refute the correspondence theory of truth. Stephen Neale (1995) claims, controversially, that the most compelling version was suggested by Kurt Gödel (1944). These arguments are sometimes modified to support the alternative, and evidently stronger, conclusion that there is only one ''fact'', or one true ''proposition'', ''state of affairs'', ''truth condition'', ''truthmaker'', and so on. ==The argument== One version of the argument (Perry 1996) proceeds as follows. Assumptions: # Substitution. If two terms designate the same thing, then substituting one for another in a sentence does not change the designation of that sentence. # Redistribution. Rearranging the parts of a sentence does not change the designation of that sentence, provided the truth conditions of the sentence do not change. # Every sentence is equivalent to a sentence of the form ''F''(''a''). In other words, every sentence has the same designation as some sentence that attributes a property to something. (For example, "All men are mortal" is equivalent to "The number 1 has the property of being such that all men are mortal".) # For any two objects there is a relation that holds uniquely between them. (For example, if the objects in question are denoted by "''a''" and "''b''", the relation in question might be ''R''(''x'', ''y''), which is stipulated to hold just in case ''x'' = ''a'' and ''y'' = ''b''.) Let ''S'' and ''T'' be arbitrary true sentences, designating ''Des''(''S'') and ''Des''(''T''), respectively. (No assumptions are made about what kinds of things ''Des''(''S'') and ''Des''(''T'') are.) It is now shown by a series of designation-preserving transformations that ''Des''(''S'') = ''Des''(''T''). Here, "" can be read as "the ''x'' such that". Note that (1)-(9) is not a derivation of ''T'' from ''S''. Rather, it is a series of (allegedly) designation-preserving transformation steps. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Slingshot argument」の詳細全文を読む スポンサード リンク
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