First-Order Modal Logic
First-Order Modal Logic
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DOI:
10.1007/978-94-011-5292-1
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发表时间:
1998-10
期刊:
影响因子:
--
通讯作者:
M. Fitting;Richard L. Mendelsohn
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文献类型:
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作者:
M. Fitting;Richard L. Mendelsohn
After a rocky start in the first half of the twentieth century, modal logic hit its stride in the second half. The introduction of possible world semantics around the midcentury mark made the difference. Possible world semantics provided a technical device with intuitive appeal, and almost overnight the subject became something people felt they understood, rightly or wrongly. Today there are many books that deal with modal logic. But with only a small number of exceptions, treatments are almost entirely of propositional modal logic. By now this is a well-worked area and a standard part of philosophical training. First-order modal logic, on the other hand, is under-represented in the literature. It is not simply propositional modal logic plus quantifiers. Complications arise that have no counterpart in classical logic. The results are nuanced and expressive. That is what this book is about. To make our book self-contained, we incorporate a refresher for those who need it, on classical propositional logic both axiomatically and with tableau systems, and with detailed proofs of soundness and completeness. Then we move on to modal logics. We begin with propositional modal logic, and our presentation here is typical of the entire book. Our basic approach is semantic, using possible world, or Kripke, models. Proof-theoretically, our primary machinery is semantic tableaus, which are easy and intuitive to use. We also include a treatment of propositional axiom systems, though axiomatics do not continue throughout the book. Philosophically, we discuss the issues that motivate formal modal logics and consider what bearing technical developments have on well-known philosophical problems. This three-pronged approach, Kripke semantics, tableaus, and philosophical discussion, reappears as each new topic is introduced. Classically, first-order issues like constant and function symbols, equality, quantification, and definite descriptions, have straightforward formal treatments that have been standard items for a long time. Modally, each of these items needs rethinking. As noted above, first-order modal logic, most decidedly, is not just propositional modal logic plus classical quantifier machinery. The situation is much subtler than vii