Combining Texts

All the ideas for 'Analyzing Modality', 'The Life of Reason' and 'Which Logic is the Right Logic?'

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31 ideas

1. Philosophy / C. History of Philosophy / 1. History of Philosophy
8000 He who is ignorant of the history of philosophy is doomed to repeat it [Santayana, by MacIntyre]
4. Formal Logic / F. Set Theory ST / 4. Axioms for Sets / j. Axiom of Choice IX
10775 The axiom of choice now seems acceptable and obvious (if it is meaningful) [Tharp]
5. Theory of Logic / A. Overview of Logic / 1. Overview of Logic
10766 Logic is either for demonstration, or for characterizing structures [Tharp]
5. Theory of Logic / A. Overview of Logic / 5. First-Order Logic
10767 Elementary logic is complete, but cannot capture mathematics [Tharp]
5. Theory of Logic / A. Overview of Logic / 7. Second-Order Logic
10769 Second-order logic isn't provable, but will express set-theory and classic problems [Tharp]
5. Theory of Logic / E. Structures of Logic / 2. Logical Connectives / b. Basic connectives
10762 In sentential logic there is a simple proof that all truth functions can be reduced to 'not' and 'and' [Tharp]
5. Theory of Logic / G. Quantification / 2. Domain of Quantification
10776 The main quantifiers extend 'and' and 'or' to infinite domains [Tharp]
5. Theory of Logic / G. Quantification / 3. Objectual Quantification
11115 'All horses' either picks out the horses, or the things which are horses [Jubien]
5. Theory of Logic / G. Quantification / 7. Unorthodox Quantification
10774 There are at least five unorthodox quantifiers that could be used [Tharp]
5. Theory of Logic / J. Model Theory in Logic / 3. Löwenheim-Skolem Theorems
10777 Skolem mistakenly inferred that Cantor's conceptions were illusory [Tharp]
10773 The Löwenheim-Skolem property is a limitation (e.g. can't say there are uncountably many reals) [Tharp]
5. Theory of Logic / K. Features of Logics / 3. Soundness
10765 Soundness would seem to be an essential requirement of a proof procedure [Tharp]
5. Theory of Logic / K. Features of Logics / 4. Completeness
10763 Completeness and compactness together give axiomatizability [Tharp]
5. Theory of Logic / K. Features of Logics / 5. Incompleteness
10770 If completeness fails there is no algorithm to list the valid formulas [Tharp]
5. Theory of Logic / K. Features of Logics / 6. Compactness
10771 Compactness is important for major theories which have infinitely many axioms [Tharp]
10772 Compactness blocks infinite expansion, and admits non-standard models [Tharp]
5. Theory of Logic / K. Features of Logics / 8. Enumerability
10764 A complete logic has an effective enumeration of the valid formulas [Tharp]
10768 Effective enumeration might be proved but not specified, so it won't guarantee knowledge [Tharp]
9. Objects / A. Existence of Objects / 1. Physical Objects
11116 Being a physical object is our most fundamental category [Jubien]
9. Objects / A. Existence of Objects / 5. Individuation / d. Individuation by haecceity
11117 Haecceities implausibly have no qualities [Jubien]
10. Modality / A. Necessity / 11. Denial of Necessity
11119 De re necessity is just de dicto necessity about object-essences [Jubien]
10. Modality / C. Sources of Modality / 5. Modality from Actuality
11118 Modal propositions transcend the concrete, but not the actual [Jubien]
11108 Your properties, not some other world, decide your possibilities [Jubien]
11111 Modal truths are facts about parts of this world, not about remote maximal entities [Jubien]
10. Modality / E. Possible worlds / 1. Possible Worlds / e. Against possible worlds
11105 We have no idea how many 'possible worlds' there might be [Jubien]
11107 If there are no other possible worlds, do we then exist necessarily? [Jubien]
11106 If all possible worlds just happened to include stars, their existence would be necessary [Jubien]
11112 Possible worlds just give parallel contingencies, with no explanation at all of necessity [Jubien]
11109 If other worlds exist, then they are scattered parts of the actual world [Jubien]
11113 Worlds don't explain necessity; we use necessity to decide on possible worlds [Jubien]
10. Modality / E. Possible worlds / 3. Transworld Objects / c. Counterparts
11110 We mustn't confuse a similar person with the same person [Jubien]