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Single Idea 10621

[filed under theme 5. Theory of Logic / K. Features of Logics / 5. Incompleteness ]

Full Idea

Where Gödel's First Theorem sabotages logicist ambitions, the Second Theorem sabotages Hilbert's Programme.

Gist of Idea

Gödel's First Theorem sabotages logicism, and the Second sabotages Hilbert's Programme

Source

comment on Kurt Gödel (On Formally Undecidable Propositions [1931]) by Peter Smith - Intro to Gödel's Theorems 36

Book Ref

Smith,Peter: 'An Introduction to Gödel's Theorems' [CUP 2007], p.343


A Reaction

Neo-logicism (Crispin Wright etc.) has a strategy for evading the First Theorem.


The 10 ideas with the same theme [some truths of a system evade formal proof]:

We can assign a characteristic number to every single object [Leibniz]
Gödel's First Theorem sabotages logicism, and the Second sabotages Hilbert's Programme [Smith,P on Gödel]
The undecidable sentence can be decided at a 'higher' level in the system [Gödel]
Gödel's Theorems did not refute the claim that all good mathematical questions have answers [Gödel, by Koellner]
If completeness fails there is no algorithm to list the valid formulas [Tharp]
Two routes to Incompleteness: semantics of sound/expressible, or syntax of consistency/proof [Smith,P]
We have no argument to show a statement is absolutely undecidable [Koellner]
The first incompleteness theorem means that consistency does not entail soundness [Horsten]
A deductive system is only incomplete with respect to a formal semantics [Rossberg]
Axioms are ω-incomplete if the instances are all derivable, but the universal quantification isn't [Engelbretsen/Sayward]