> If a
> sighted man says "le ciel est bleu" to a colorblind man and a blind man,
> one will disagree or consider it a difference of opinion, and the other
> one will have to accept it as hearsay.
True, but if "blue" is strictly defined (which is the sort of thing you
can do when you're talking about meta languages) then the sky TRULY is or
isn't blue. That it becomes black at night doesn't negate the proof; even
then, it truly is or isn't black.
How to identify the truth is a separate point which I don't think Tarski
answers; he merely shows that there IS truth. (An important
accomplishment, especially in the face of certain sollipsists who assert
that the truth is whatever we think it is.)