Full Idea
We have to wonder how we know that it is some single concept which Tarski indicates how to define for each of a number of well-behaved languages.
Gist of Idea
When Tarski defines truth for different languages, how do we know it is a single concept?
Source
Donald Davidson (Truth Rehabilitated [1997], P.11)
Book Reference
Davidson,Donald: 'Truth, Language and History' [OUP 2005], p.11
A Reaction
Davidson says that Tarski makes the assumption that it is a single concept, but fails to demonstrate the fact. This resembles Frege's Julius Caesar problem - of how you know whether your number definition has defined a number.