That is all clear, and it's what I have been talking about from the OP in this thread.
And in the scenario where the presupposition is false, the truth value of the sentence bearing the presupposition becomes harder to evaluate. If the Mona Lisa was not actually stolen, then The Mona Lisa was stolen by Carmen Sandiego is simply a false sentence. But if the Mona Lisa was not stolen, then The one who stole the Mona Lisa was Carmen Sandiego is certainly not true, but it's hard to say that it's false, either—it's hard to evaluate.
Exactly. And I would say that it's not only hard but impossible to evaluate. This goes against what the people who oddly liked your post have been saying. They're saying that, if the Mona Lisa was not stolen,
"The one who stole the Mona Lisa was Carmen Sandiego" is
false.
And now I see that you agreed with Jack Rudd's post, which means you're contradicting your own post...?
I read about Russell's analysis of the King of France statement. It's just one theory, and one I don't agree with - especially in normal language.
Exactly as AJD illustrated:
"The king of France is bald."
"What? I don't think there's a king of France?"
It seems that Russell makes a weak argument,
based on the WP article, since he analyzes the statement "the present King of France is bald" by making three statements, the first of which says that there is a King of France, and then concludes that the original statement must be false because there is no King of France. Essentially he's simply stating that the statement must be false
because it has a false supposition.
EDIT: Yes, Russell is asserting that the statement "the present King of France is bald" contains an unspoken, hidden statement "there is presently a King of France".
EDIT2: And indeed, the theory of
presuppositions is by Frege and is in opposition to Russell's theory. According to Frege, statements with false presuppositions fail to have a truth value. They're neither true nor false.