Combining Texts

All the ideas for 'Analyzing Modality', 'What is Logic?' and 'Time and Free Will'

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26 ideas

2. Reason / D. Definition / 3. Types of Definition
13838 A decent modern definition should always imply a semantics [Hacking]
4. Formal Logic / B. Propositional Logic PL / 2. Tools of Propositional Logic / d. Basic theorems of PL
13834 Gentzen's Cut Rule (or transitivity of deduction) is 'If A |- B and B |- C, then A |- C' [Hacking]
13835 Only Cut reduces complexity, so logic is constructive without it, and it can be dispensed with [Hacking]
13833 'Thinning' ('dilution') is the key difference between deduction (which allows it) and induction [Hacking]
5. Theory of Logic / A. Overview of Logic / 4. Pure Logic
13845 The various logics are abstractions made from terms like 'if...then' in English [Hacking]
5. Theory of Logic / A. Overview of Logic / 5. First-Order Logic
13840 First-order logic is the strongest complete compact theory with Löwenheim-Skolem [Hacking]
13844 A limitation of first-order logic is that it cannot handle branching quantifiers [Hacking]
5. Theory of Logic / A. Overview of Logic / 7. Second-Order Logic
13842 Second-order completeness seems to need intensional entities and possible worlds [Hacking]
5. Theory of Logic / E. Structures of Logic / 2. Logical Connectives / a. Logical connectives
13837 With a pure notion of truth and consequence, the meanings of connectives are fixed syntactically [Hacking]
5. Theory of Logic / E. Structures of Logic / 4. Variables in Logic
13839 Perhaps variables could be dispensed with, by arrows joining places in the scope of quantifiers [Hacking]
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 / J. Model Theory in Logic / 3. Löwenheim-Skolem Theorems
13843 If it is a logic, the Löwenheim-Skolem theorem holds for it [Hacking]
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]
11109 If other worlds exist, then they are scattered parts of the actual world [Jubien]
11106 If all possible worlds just happened to include stars, their existence would be necessary [Jubien]
11107 If there are no other possible worlds, do we then exist necessarily? [Jubien]
11112 Possible worlds just give parallel contingencies, with no explanation at all of necessity [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]
17. Mind and Body / E. Mind as Physical / 5. Causal Argument
22100 Experienced time means no two mental moments are ever alike [Bergson]