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Single Idea 3198

[filed under theme 6. Mathematics / B. Foundations for Mathematics / 4. Axioms for Number / g. Incompleteness of Arithmetic ]

Full Idea

Gödel's theorem states that either arithmetic is incomplete, or it is inconsistent.

Gist of Idea

Gödel showed that arithmetic is either incomplete or inconsistent

Source

report of Kurt Gödel (On Formally Undecidable Propositions [1931]) by Georges Rey - Contemporary Philosophy of Mind 8.7

Book Ref

Rey,Georges: 'Contemporary Philosophy of Mind' [Blackwell 1997], p.224


The 21 ideas with the same theme [discovery that axioms can't prove all truths of arithmetic]:

We can add Reflexion Principles to Peano Arithmetic, which assert its consistency or soundness [Halbach on Peano]
Gödel showed that arithmetic is either incomplete or inconsistent [Gödel, by Rey]
First Incompleteness: arithmetic must always be incomplete [Gödel, by Smith,P]
Arithmetical truth cannot be fully and formally derived from axioms and inference rules [Gödel, by Nagel/Newman]
Gödel's Second says that semantic consequence outruns provability [Gödel, by Hanna]
First Incompleteness: a decent consistent system is syntactically incomplete [Gödel, by George/Velleman]
Second Incompleteness: a decent consistent system can't prove its own consistency [Gödel, by George/Velleman]
There is a sentence which a theory can show is true iff it is unprovable [Gödel, by Smith,P]
'This system can't prove this statement' makes it unprovable either way [Gödel, by Clegg]
Some arithmetical problems require assumptions which transcend arithmetic [Gödel]
Gödel eventually hoped for a generalised completeness theorem leaving nothing undecidable [Gödel, by Koellner]
The real reason for Incompleteness in arithmetic is inability to define truth in a language [Gödel]
Gentzen proved the consistency of arithmetic from assumptions beyond arithmetic [Gentzen, by Musgrave]
Intuitionists find the Incompleteness Theorem unsurprising, since proof is intuitive, not formal [Dummett]
Incompleteness results in arithmetic from combining addition and successor with multiplication [Smith,P]
Multiplication only generates incompleteness if combined with addition and successor [Smith,P]
It is only 2nd-order isomorphism which suggested first-order PA completeness [Mayberry]
The incompletability of formal arithmetic reveals that logic also cannot be completely characterized [Hale/Wright]
The Incompleteness proofs use arithmetic to talk about formal arithmetic [George/Velleman]
Arithmetical undecidability is always settled at the next stage up [Koellner]
You can't prove consistency using a weaker theory, but you can use a consistent theory [Linnebo]