Deflationary truth and the ontology of expressions
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The existence of a close connection between results on axiomatic truth and the analysis of truth-theoretic deflationism is nowadays widely recognized. The first attempt to make such link precise can be traced back to the so-called conservativeness argument due to Leon Horsten, Stewart Shapiro and Jeffrey Ketland: by employing standard Gödelian phenomena, they concluded that deflationism is untenable as any adequate theory of truth leads to consequences that were not achievable by the base theory alone. In the paper I highlight, as Shapiro and Ketland, the irreducible nature of truth axioms with respect to their base theories. But, I argue, this does not immediately delineate a notion of truth playing a substantial role in philosophical or scientific explanations. I first offer a refinement of Hartry Field’s reaction to the conservativeness argument by distinguishing between metatheoretic and object-theoretic consequences of the theory of truth and address some possible rejoinders. In the resulting picture, truth is an irreducible tool for metatheoretic ascent. How robust is this characterizaton? I test it by considering: (i) a recent example, due to Leon Horsten, of the alleged explanatory role played by the truth predicate in the derivation of Fitch’s paradox; (ii) an essential weakening of theories of truth analyzed in the first part of the paper.
KeywordsTruth theoretic deflationism Axiomatic theories of truth Conservativeness argument Relative interpretability
This work was supported by the Art and Humanities Research Council UK AH/H039791/1 and by the Analysis Trust. I would like to thank Martin Fischer, Volker Halbach, Richard Heck, Leon Horsten, Jeffrey Ketland and two anonymous referees for their comments and suggestions.
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