Combining Texts

All the ideas for 'The Sign of Four', 'Letters to Pierre Bayle' and 'Logical Consequence'

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10 ideas

5. Theory of Logic / B. Logical Consequence / 1. Logical Consequence
Validity is explained as truth in all models, because that relies on the logical terms [McGee]
5. Theory of Logic / E. Structures of Logic / 2. Logical Connectives / a. Logical connectives
Natural language includes connectives like 'because' which are not truth-functional [McGee]
5. Theory of Logic / G. Quantification / 5. Second-Order Quantification
Second-order variables need to range over more than collections of first-order objects [McGee]
5. Theory of Logic / I. Semantics of Logic / 1. Semantics of Logic
An ontologically secure semantics for predicate calculus relies on sets [McGee]
5. Theory of Logic / I. Semantics of Logic / 3. Logical Truth
Logically valid sentences are analytic truths which are just true because of their logical words [McGee]
5. Theory of Logic / K. Features of Logics / 3. Soundness
Soundness theorems are uninformative, because they rely on soundness in their proofs [McGee]
6. Mathematics / B. Foundations for Mathematics / 3. Axioms for Geometry
The culmination of Euclidean geometry was axioms that made all models isomorphic [McGee]
14. Science / C. Induction / 1. Induction
If you eliminate the impossible, the truth will remain, even if it is weird [Conan Doyle]
16. Persons / F. Free Will / 5. Against Free Will
If we know what is good or rational, our knowledge is extended, and our free will restricted [Leibniz]
19. Language / F. Communication / 2. Assertion
A maxim claims that if we are allowed to assert a sentence, that means it must be true [McGee]