Combining Texts

All the ideas for 'The Poetics', 'A Tour through Mathematical Logic' and 'The Meaning of 'Meaning''

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30 ideas

4. Formal Logic / B. Propositional Logic PL / 2. Tools of Propositional Logic / b. Terminology of PL
13520 A 'tautology' must include connectives [Wolf,RS]
4. Formal Logic / B. Propositional Logic PL / 2. Tools of Propositional Logic / c. Derivation rules of PL
13524 Deduction Theorem: T∪{P}|-Q, then T|-(P→Q), which justifies Conditional Proof [Wolf,RS]
4. Formal Logic / C. Predicate Calculus PC / 2. Tools of Predicate Calculus / d. Universal quantifier ∀
13521 Universal Specification: ∀xP(x) implies P(t). True for all? Then true for an instance [Wolf,RS]
13522 Universal Generalization: If we prove P(x) with no special assumptions, we can conclude ∀xP(x) [Wolf,RS]
4. Formal Logic / C. Predicate Calculus PC / 2. Tools of Predicate Calculus / e. Existential quantifier ∃
13523 Existential Generalization (or 'proof by example'): if we can say P(t), then we can say something is P [Wolf,RS]
4. Formal Logic / F. Set Theory ST / 4. Axioms for Sets / e. Axiom of the Empty Set IV
13529 Empty Set: ∃x∀y ¬(y∈x). The unique empty set exists [Wolf,RS]
4. Formal Logic / F. Set Theory ST / 4. Axioms for Sets / n. Axiom of Comprehension
13526 Comprehension Axiom: if a collection is clearly specified, it is a set [Wolf,RS]
5. Theory of Logic / A. Overview of Logic / 5. First-Order Logic
13534 In first-order logic syntactic and semantic consequence (|- and |=) nicely coincide [Wolf,RS]
13535 First-order logic is weakly complete (valid sentences are provable); we can't prove every sentence or its negation [Wolf,RS]
5. Theory of Logic / J. Model Theory in Logic / 1. Logical Models
13519 Model theory uses sets to show that mathematical deduction fits mathematical truth [Wolf,RS]
13531 Model theory reveals the structures of mathematics [Wolf,RS]
13532 Model theory 'structures' have a 'universe', some 'relations', some 'functions', and some 'constants' [Wolf,RS]
13533 First-order model theory rests on completeness, compactness, and the Löwenheim-Skolem-Tarski theorem [Wolf,RS]
5. Theory of Logic / J. Model Theory in Logic / 2. Isomorphisms
13537 An 'isomorphism' is a bijection that preserves all structural components [Wolf,RS]
5. Theory of Logic / J. Model Theory in Logic / 3. Löwenheim-Skolem Theorems
13539 The LST Theorem is a serious limitation of first-order logic [Wolf,RS]
5. Theory of Logic / K. Features of Logics / 4. Completeness
13538 If a theory is complete, only a more powerful language can strengthen it [Wolf,RS]
5. Theory of Logic / K. Features of Logics / 10. Monotonicity
13525 Most deductive logic (unlike ordinary reasoning) is 'monotonic' - we don't retract after new givens [Wolf,RS]
6. Mathematics / A. Nature of Mathematics / 3. Nature of Numbers / e. Ordinal numbers
13530 An ordinal is an equivalence class of well-orderings, or a transitive set whose members are transitive [Wolf,RS]
6. Mathematics / B. Foundations for Mathematics / 6. Mathematics as Set Theory / a. Mathematics is set theory
13518 Modern mathematics has unified all of its objects within set theory [Wolf,RS]
9. Objects / D. Essence of Objects / 15. Against Essentialism
18890 Putnam smuggles essentialism about liquids into his proof that water must be H2O [Salmon,N on Putnam]
10. Modality / B. Possibility / 1. Possibility
22518 The actual must be possible, because it occurred [Aristotle]
15. Nature of Minds / B. Features of Minds / 5. Qualia / b. Qualia and intentionality
7705 The Twin Earth theory suggests that intentionality is independent of qualia [Jacquette on Putnam]
18. Thought / C. Content / 5. Twin Earth
4099 If Twins talking about 'water' and 'XYZ' have different thoughts but identical heads, then thoughts aren't in the head [Putnam, by Crane]
12026 We say ice and steam are different forms of water, but not that they are different forms of H2O [Forbes,G on Putnam]
3208 Does 'water' mean a particular substance that was 'dubbed'? [Putnam, by Rey]
19. Language / B. Reference / 4. Descriptive Reference / a. Sense and reference
3893 Often reference determines sense, and not (as Frege thought) vice versa [Putnam, by Scruton]
21. Aesthetics / B. Nature of Art / 8. The Arts / b. Literature
16566 Poetry is more philosophic than history, as it concerns universals, not particulars [Aristotle]
26. Natural Theory / B. Natural Kinds / 4. Source of Kinds
11191 The hidden structure of a natural kind determines membership in all possible worlds [Putnam]
26. Natural Theory / D. Laws of Nature / 8. Scientific Essentialism / a. Scientific essentialism
11192 If causes are the essence of diseases, then disease is an example of a relational essence [Putnam, by Williams,NE]
11190 Archimedes meant by 'gold' the hidden structure or essence of the stuff [Putnam]