Combining Texts

All the ideas for 'Mereology', 'Ignorance: a Case for Scepticism' and 'A Tour through Mathematical Logic'

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33 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 ∀
13522 Universal Generalization: If we prove P(x) with no special assumptions, we can conclude ∀xP(x) [Wolf,RS]
13521 Universal Specification: ∀xP(x) implies P(t). True for all? Then true for an instance [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 / a. Axioms for sets
10653 Maybe set theory need not be well-founded [Varzi]
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]
4. Formal Logic / G. Formal Mereology / 1. Mereology
10648 Mereology need not be nominalist, though it is often taken to be so [Varzi]
10655 Are there mereological atoms, and are all objects made of them? [Varzi]
10659 There is something of which everything is part, but no null-thing which is part of everything [Varzi]
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
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]
13519 Model theory uses sets to show that mathematical deduction fits mathematical truth [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 / C. Structure of Objects / 5. Composition of an Object
10661 'Composition is identity' says multitudes are the reality, loosely composing single things [Varzi]
9. Objects / C. Structure of Objects / 8. Parts of Objects / a. Parts of objects
10647 Parts may or may not be attached, demarcated, arbitrary, material, extended, spatial or temporal [Varzi]
10651 If 'part' is reflexive, then identity is a limit case of parthood [Varzi]
10649 'Part' stands for a reflexive, antisymmetric and transitive relation [Varzi]
10654 The parthood relation will help to define at least seven basic predicates [Varzi]
9. Objects / C. Structure of Objects / 8. Parts of Objects / c. Wholes from parts
10658 Sameness of parts won't guarantee identity if their arrangement matters [Varzi]
10. Modality / D. Knowledge of Modality / 4. Conceivable as Possible / b. Conceivable but impossible
10652 Conceivability may indicate possibility, but literary fantasy does not [Varzi]
13. Knowledge Criteria / C. External Justification / 6. Contextual Justification / b. Invariantism
8724 The meaning of 'know' does not change from courtroom to living room [Unger]
13. Knowledge Criteria / D. Scepticism / 1. Scepticism
8722 No one knows anything, and no one is ever justified or reasonable [Unger]
13. Knowledge Criteria / D. Scepticism / 4. Demon Scepticism
8723 An evil scientist may give you a momentary life, with totally false memories [Unger]