Davidson's "The Folly of Trying to Define Truth"

Davidson's "The Folly of Trying to Define Truth"

Davidson’s argument against the possibility of defining truth draws upon the work of Tarski. However, Tarski’s assumption that the semantic conception of truth holds only for formal languages which are not semantically closed is not as plausible as it seems to be since it can be shown that this would result in the impossibility of formulating a theory of truth, because the epistemological presuppositions of formal semantics undermine any theory of representation of reality in which our cognitions can be true or false representations. Yet Davidson concludes that "there cannot be a definition of ‘For all languages L, and all sentences s in L, s is true in L if and only if . . . s . . . L’." I am challenging Davidson by introducing into his above scheme my own definition of truth — "For all languages L, and all sentences s in L, s is true in L if and only if we prove s in L" — and then showing how to prove this definition philosophically.

I. Introduction: Can we define truth?

Davidson argues for "the folly of trying to define truth" and claims that Tarski's "accomplishment was accompanied by a proof that truth cannot (given various plausible assumptions) be defined in general" (Davidson, 1996:269). Tarski's plausible assumptions are that his "semantic conception of truth" can be formulated only for formal languages which are not semantically closed. But these assumptions are not so plausible as they seem since it can be shown that if we accept them it is impossible to formulate a theory of truth because the epistemological presuppositions of formal semantics undermine any theory of representation of reality in which our cognitions can be true or false representations (Nesher, 1996). Yet Davidson concludes from Tarski's theory of truth that "there cannot be definition of `For all languages L, and all sentences s in L, s is true in L if and only if ... s ... L'."

I would like to start by challenging Davidson about his claim for the impossibility of defining truth and to introduce into his above scheme my own definition of truth; then I will show how to prove this definition philosophically:

[1] `For all languages L, and all sentences s in L, s is true in L if and only if we prove s in L'.

We can see immediately that the plausible assumptions of Tarski's "semantic conception of truth" for semantically formal languages do not hold in my definition of truth since I define truth in the same language in which it is used.