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THE EXPRESSIVE POWER OF TRUTH

Published online by Cambridge University Press:  15 December 2014

MARTIN FISCHER*
Affiliation:
MCMP, LMU München
LEON HORSTEN*
Affiliation:
Department of Philosophy, University of Bristol
*
*MUNICH CENTER FOR MATHEMATICAL PHILOSOPHY FAKULTÄT FÜR PHILOSOPHIE WISSENSCHAFTSTHEORIE UND RELIGIONSWISSENSCHAFTEN LMU MÜNCHEN, GESCHWISTER SCHOLL PLATZ 1 D-80539 MÜNCHEN, GERMANY E-mail: M.Fischer@lrz.uni-muenchen.de
DEPARTMENT OF PHILOSOPHY 43 WOODLAND ROAD BS83PE, BRISTOL, UK E-mail: leon.horsten@bristol.ac.uk

Abstract

There are two perspectives from which formal theories can be viewed. On the one hand, one can take a theory to be about some privileged models. On the other hand, one can take all models of a theory to be on a par. In contrast with what is usually done in philosophical debates, we adopt the latter viewpoint. Suppose that from this perspective we want to add an adequate truth predicate to a background theory. Then on the one hand the truth theory ought to be semantically conservative over the background theory. At the same time, it is generally recognised that the central function of a truth predicate is an expressive one. A truth predicate ought to allow us to express propositions that we could not express before. In this article we argue that there are indeed natural truth theories which satisfy both the demand of semantical conservativeness and the demand of adequately extending the expressive power of our language.

Type
Research Article
Copyright
Copyright © Association for Symbolic Logic 2014 

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