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 opaque contexts.[1]
The literal translation of the Latin "salva veritate" is "with (or by) unharmed truth", using ablative of manner: "salva" meaning "rescue," "salvation," or "welfare," and "veritate" meaning "reality" or "truth".
The phrase occurs in two fragments from Gottfried Leibniz's General Science. Characteristics:
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.[2] 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whole quantified modal logic of necessity is dependent on context and empty otherwise; for it collapses if essence is withdrawn.[3]
For example, the statements:
| (1) | Giorgione = Barbarelli, | |
| (2) | Giorgione was so-called because of his size |
| Barbarelli was so-called because of his size.[4] |
Quine's example here refers to Giorgio Barbarelli's sobriquet "Giorgione", an Italian name roughly glossed as "Big George."