Combining Texts

All the ideas for 'On Certainty', 'On Second-Order Logic' and 'Philosophy of Science'

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19 ideas

5. Theory of Logic / A. Overview of Logic / 7. Second-Order Logic
Boolos reinterprets second-order logic as plural logic [Boolos, by Oliver/Smiley]
Second-order logic metatheory is set-theoretic, and second-order validity has set-theoretic problems [Boolos]
5. Theory of Logic / C. Ontology of Logic / 1. Ontology of Logic
A sentence can't be a truth of logic if it asserts the existence of certain sets [Boolos]
5. Theory of Logic / G. Quantification / 2. Domain of Quantification
'∀x x=x' only means 'everything is identical to itself' if the range of 'everything' is fixed [Boolos]
5. Theory of Logic / K. Features of Logics / 4. Completeness
Weak completeness: if it is valid, it is provable. Strong: it is provable from a set of sentences [Boolos]
5. Theory of Logic / K. Features of Logics / 6. Compactness
Why should compactness be definitive of logic? [Boolos, by Hacking]
6. Mathematics / B. Foundations for Mathematics / 4. Axioms for Number / e. Peano arithmetic 2nd-order
Many concepts can only be expressed by second-order logic [Boolos]
13. Knowledge Criteria / B. Internal Justification / 4. Foundationalism / a. Foundationalism
Foundations need not precede other beliefs [Wittgenstein]
13. Knowledge Criteria / D. Scepticism / 6. Scepticism Critique
Total doubt can't even get started [Wittgenstein, by Williams,M]
14. Science / A. Basis of Science / 6. Falsification
Why abandon a theory if you don't have a better one? [Gorham]
If a theory is more informative it is less probable [Gorham]
14. Science / B. Scientific Theories / 1. Scientific Theory
Is Newton simpler with universal simultaneity, or Einstein simpler without absolute time? [Gorham]
Structural Realism says mathematical structures persist after theory rejection [Gorham]
Structural Realists must show the mathematics is both crucial and separate [Gorham]
14. Science / B. Scientific Theories / 3. Instrumentalism
Theories aren't just for organising present experience if they concern the past or future [Gorham]
For most scientists their concepts are not just useful, but are meant to be true and accurate [Gorham]
14. Science / D. Explanation / 2. Types of Explanation / d. Consilience
Consilience makes the component sciences more likely [Gorham]
19. Language / A. Nature of Meaning / 10. Denial of Meanings
If you are not certain of any fact, you cannot be certain of the meaning of your words either [Wittgenstein]
26. Natural Theory / A. Speculations on Nature / 1. Nature
Aristotelian physics has circular celestial motion and linear earthly motion [Gorham]