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Single Idea 10065

[filed under theme 5. Theory of Logic / C. Ontology of Logic / 3. If-Thenism ]

Full Idea

If we identify logic with first-order logic, and mathematics with the collection of first-order theories, then maybe we can continue to maintain the If-thenist position.

Gist of Idea

Perhaps If-thenism survives in mathematics if we stick to first-order logic

Source

Alan Musgrave (Logicism Revisited [1977], §5)

Book Ref

-: 'British Soc for the Philosophy of Science' [-], p.124


A Reaction

The problem is that If-thenism must rely on rules of inference. That seems to mean that what is needed is Soundness, rather than Completeness. That is, inference by the rules must work properly.


The 8 ideas from 'Logicism Revisited'

Logical truths may contain non-logical notions, as in 'all men are men' [Musgrave]
A statement is logically true if it comes out true in all interpretations in all (non-empty) domains [Musgrave]
Logical positivists adopted an If-thenist version of logicism about numbers [Musgrave]
No two numbers having the same successor relies on the Axiom of Infinity [Musgrave]
Formalism seems to exclude all creative, growing mathematics [Musgrave]
Formalism is a bulwark of logical positivism [Musgrave]
The If-thenist view only seems to work for the axiomatised portions of mathematics [Musgrave]
Perhaps If-thenism survives in mathematics if we stick to first-order logic [Musgrave]