On the Invariance of Gödel's Second Theorem with regard to Numberings

Balthasar Grabmayr

doi:10.1017/s1755020320000192

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arXiv · 1803.08392

On the Invariance of Gödel's Second Theorem with regard to Numberings

Balthasar Grabmayr

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Abstract

The prevalent interpretation of Gödel's Second Theorem states that a sufficiently adequate and consistent theory does not prove its consistency. It is however not entirely clear how to justify this informal reading, as the formulation of the underlying mathematical theorem depends on several arbitrary formalisation choices. In this paper I examine the theorem's dependency regarding Gödel numberings. I introduce deviant numberings, yielding provability predicates satisfying Löb's conditions, which result in provable consistency sentences. According to the main result of this paper however, these "counterexamples" do not refute the theorem's prevalent interpretation, since once a natural class of admissible numberings is singled out, invariance is maintained.

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BibTeX RIS

Balthasar Grabmayr. 2020-06-02. On the Invariance of Gödel's Second Theorem with regard to Numberings. https://doi.org/10.1017/s1755020320000192

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