Substitution salva veritate

Definition
Substitution salva veritate is the possibility of replacing an expression alpha by an expression beta with the same reference in such a way that the resulting sentence has the same truth-value.

Example
Given that Beatrix is the eldest daughter of Juliana sentence (i)a is equivalent to (i)b in which the eldest daughter of Juliana has been substituted for Beatrix. Hence the substitution is salva veritate.

(i) a Beatrix lives in The Hague b The eldest daughter of Juliana lives in The Hague

Substitution salva veritate is not possible in opaque contexts.

Links

 * Utrecht Lexicon of Linguistics