Combining Philosophers

All the ideas for Agrippa, Michael Hallett and Alan Musgrave

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18 ideas

2. Reason / A. Nature of Reason / 9. Limits of Reason
Reasoning needs arbitrary faith in preliminary hypotheses (Mode 14) [Agrippa, by Diog. Laertius]
All discussion is full of uncertainty and contradiction (Mode 11) [Agrippa, by Diog. Laertius]
Proofs often presuppose the thing to be proved (Mode 15) [Agrippa, by Diog. Laertius]
All reasoning endlessly leads to further reasoning (Mode 12) [Agrippa, by Diog. Laertius]
4. Formal Logic / F. Set Theory ST / 4. Axioms for Sets / a. Axioms for sets
The first-order ZF axiomatisation is highly non-categorical [Hallett,M]
Non-categoricity reveals a sort of incompleteness, with sets existing that the axioms don't reveal [Hallett,M]
4. Formal Logic / F. Set Theory ST / 7. Natural Sets
Zermelo allows ur-elements, to enable the widespread application of set-theory [Hallett,M]
5. Theory of Logic / C. Ontology of Logic / 3. If-Thenism
Perhaps If-thenism survives in mathematics if we stick to first-order logic [Musgrave]
The If-thenist view only seems to work for the axiomatised portions of mathematics [Musgrave]
5. Theory of Logic / I. Semantics of Logic / 3. Logical Truth
A statement is logically true if it comes out true in all interpretations in all (non-empty) domains [Musgrave]
Logical truths may contain non-logical notions, as in 'all men are men' [Musgrave]
6. Mathematics / A. Nature of Mathematics / 5. The Infinite / g. Continuum Hypothesis
The General Continuum Hypothesis and its negation are both consistent with ZF [Hallett,M]
6. Mathematics / B. Foundations for Mathematics / 4. Axioms for Number / d. Peano arithmetic
No two numbers having the same successor relies on the Axiom of Infinity [Musgrave]
6. Mathematics / C. Sources of Mathematics / 7. Formalism
Formalism is a bulwark of logical positivism [Musgrave]
Formalism seems to exclude all creative, growing mathematics [Musgrave]
13. Knowledge Criteria / A. Justification Problems / 2. Justification Challenges / a. Agrippa's trilemma
Agrippa's Trilemma: justification is infinite, or ends arbitrarily, or is circular [Agrippa, by Williams,M]
13. Knowledge Criteria / E. Relativism / 1. Relativism
Everything is perceived in relation to another thing (Mode 13) [Agrippa, by Diog. Laertius]
19. Language / A. Nature of Meaning / 5. Meaning as Verification
Logical positivists adopted an If-thenist version of logicism about numbers [Musgrave]