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Modal logic/Quine/Hintikka: Quine has made a retreat and said that there must be nothing self-contradictory in the use of modalities in our object language.
Problem: a problem are the meta-language expressions in the object language.
Hintikka: this is indeed a problem, but only a few philosophers are aware of it.
Jaakko and Merrill B. Hintikka
The Logic of Epistemology and the Epistemology of Logic Dordrecht 1989
J. Hintikka/M. B. Hintikka
Untersuchungen zu Wittgenstein Frankfurt 1996