On the costs of nonclassical logic
Solutions to semantic paradoxes often involve restrictions of classical logic for semantic vocabulary. In the paper we investigate the costs of these restrictions in a model case. In particular, we fix two systems of truth capturing the same conception of truth: (a variant) of the system KF of [Fefe...
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| Format: | Journal article |
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Springer Netherlands
2017
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| Summary: | Solutions to semantic paradoxes often involve restrictions of classical logic for semantic vocabulary. In the paper we investigate the costs of these restrictions in a model case. In particular, we fix two systems of truth capturing the same conception of truth: (a variant) of the system KF of [Feferman 1991] formulated in classical logic, and (a variant of) the system PKF of [Halbach & Horsten 2006], formulated in basic De Morgan logic. The classical system is known to be much stronger than the nonclassical one. We assess the reasons for this asymmetry by showing that the truth theoretic principles of PKF cannot be blamed: KPF with induction restricted to non-semantic vocabulary coincides in fact with what the restricted version of KF proves true. |
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