In philosophy, salva veritate (or intersubstitutivity) is the logical condition by which two expressions may be interchanged without altering the truth-value of statements in which the expressions occur. Substitution salva veritate of co-extensional terms can fail in .[L.T.F. Gamut, Logic, Language and Meaning, 1991]
The literal translation of the Latin " salva veritate" is "with (or by) unharmed truth", using ablative: " salva" meaning "rescue," "salvation," or "welfare," and " veritate" meaning "reality" or "truth".
Leibniz
The phrase occurs in two fragments from Gottfried Leibniz's
General Science. Characteristics:
-
In Chapter 19, Definition 1, Leibniz writes: "Two terms are the same ( eadem) if one can be substituted for the other without altering the truth of any statement ( salva veritate)."
-
In Chapter 20, Definition 1, Leibniz writes: "Terms which can be substituted for one another wherever we please without altering the truth of any statement ( salva veritate), are the same ( eadem) or coincident ( coincidentia). For example, 'triangle' and 'trilateral', for in every proposition demonstrated by Euclid concerning 'triangle', 'trilateral' can be substituted without loss of truth ( salva veritate)."
Quine
W.V.O. Quine takes substitutivity
salva veritate to be the same as the "indiscernibility of identicals". Given a true statement, one of its two terms may be substituted for the other in any true statement and the result will be true.
[W.V.O. Quine, Quintessence: Reference and Modality, 2004, p. 378] He continues to show that depending on context, the statement may change in value. In fact, the whole quantified
modal logic of necessity is dependent on context and empty otherwise; for it collapses if
essence is withdrawn.
[W.V.O. Quine, Quintessence: Reference and Modality, 2004, pp. 356–357]
For example, the statements:
| (1) | Giorgione = Barbarelli, |
| (2) | Giorgione was so-called because of his size |
are true; however, replacement of the name 'Giorgione' by the name 'Barbarelli' turns (2) into the falsehood:
| | Barbarelli was so-called because of his size.[W.V.O. Quine, Quintessence: Reference and Modality, 2004, p. 361] |
Quine's example here refers to Giorgio Barbarelli's sobriquet "Giorgione", an Italian name roughly glossed as "Big George."
See also
-
Propositional attitude
-
Referential opacity
-
Rule of replacement
-
Salva congruitate
-
Truth function
-
Without loss of generality
Bibliography
-
Clarence Irving Lewis, A Survey of Symbolic Logic, Appendix, Dover.
External links
