The Soundness of First and Second Order S5 Modal Logic
نویسنده
چکیده
0. To formulate a semantic theory of modal logic it is not sufficient to define for example, the necessary as that which is true in every model and the possible as that which is true in some model. These definitions would do no more than introduce the notions of ‘necessary’ and ‘possible’ in the metalanguage. A semantics of modal logic demands that we assume an object language containing modal symbols and that we define under what conditions to attribute the values ‘true’ or ‘false’ to the formulae of this object language.
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