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Single Idea 10767
[filed under theme 5. Theory of Logic / A. Overview of Logic / 5. First-Order Logic
]
Full Idea
Elementary logic cannot characterize the usual mathematical structures, but seems to be distinguished by its completeness.
Gist of Idea
Elementary logic is complete, but cannot capture mathematics
Source
Leslie H. Tharp (Which Logic is the Right Logic? [1975], §2)
Book Ref
'Philosophy of Logic: an anthology', ed/tr. Jacquette,Dale [Blackwell 2002], p.37
The
16 ideas
from Leslie H. Tharp
10762
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In sentential logic there is a simple proof that all truth functions can be reduced to 'not' and 'and'
[Tharp]
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10763
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Completeness and compactness together give axiomatizability
[Tharp]
|
10765
|
Soundness would seem to be an essential requirement of a proof procedure
[Tharp]
|
10770
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If completeness fails there is no algorithm to list the valid formulas
[Tharp]
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10771
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Compactness is important for major theories which have infinitely many axioms
[Tharp]
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10772
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Compactness blocks infinite expansion, and admits non-standard models
[Tharp]
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10764
|
A complete logic has an effective enumeration of the valid formulas
[Tharp]
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10768
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Effective enumeration might be proved but not specified, so it won't guarantee knowledge
[Tharp]
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10766
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Logic is either for demonstration, or for characterizing structures
[Tharp]
|
10767
|
Elementary logic is complete, but cannot capture mathematics
[Tharp]
|
10769
|
Second-order logic isn't provable, but will express set-theory and classic problems
[Tharp]
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10773
|
The Löwenheim-Skolem property is a limitation (e.g. can't say there are uncountably many reals)
[Tharp]
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10775
|
The axiom of choice now seems acceptable and obvious (if it is meaningful)
[Tharp]
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10774
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There are at least five unorthodox quantifiers that could be used
[Tharp]
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10776
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The main quantifiers extend 'and' and 'or' to infinite domains
[Tharp]
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10777
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Skolem mistakenly inferred that Cantor's conceptions were illusory
[Tharp]
|