Combining Texts

All the ideas for 'A World of States of Affairs', 'Of Liberty and Necessity' and 'Higher-Order Logic'

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18 ideas

3. Truth / C. Correspondence Truth / 1. Correspondence Truth
4742 Correspondence may be one-many or many one, as when either p or q make 'p or q' true [Armstrong]
4. Formal Logic / F. Set Theory ST / 4. Axioms for Sets / j. Axiom of Choice IX
10301 The axiom of choice is controversial, but it could be replaced [Shapiro]
5. Theory of Logic / A. Overview of Logic / 5. First-Order Logic
10588 First-order logic is Complete, and Compact, with the Löwenheim-Skolem Theorems [Shapiro]
5. Theory of Logic / A. Overview of Logic / 7. Second-Order Logic
10298 Some say that second-order logic is mathematics, not logic [Shapiro]
10299 If the aim of logic is to codify inferences, second-order logic is useless [Shapiro]
5. Theory of Logic / B. Logical Consequence / 1. Logical Consequence
10300 Logical consequence can be defined in terms of the logical terminology [Shapiro]
5. Theory of Logic / G. Quantification / 5. Second-Order Quantification
10290 Second-order variables also range over properties, sets, relations or functions [Shapiro]
5. Theory of Logic / J. Model Theory in Logic / 3. Löwenheim-Skolem Theorems
10590 Up Löwenheim-Skolem: if natural numbers satisfy wffs, then an infinite domain satisfies them [Shapiro]
10296 The Löwenheim-Skolem Theorems fail for second-order languages with standard semantics [Shapiro]
10297 The Löwenheim-Skolem theorem seems to be a defect of first-order logic [Shapiro]
10292 Downward Löwenheim-Skolem: if there's an infinite model, there is a countable model [Shapiro]
6. Mathematics / B. Foundations for Mathematics / 4. Axioms for Number / e. Peano arithmetic 2nd-order
10294 Second-order logic has the expressive power for mathematics, but an unworkable model theory [Shapiro]
7. Existence / D. Theories of Reality / 7. Fictionalism
9497 Without modality, Armstrong falls back on fictionalism to support counterfactual laws [Bird on Armstrong]
8. Modes of Existence / B. Properties / 1. Nature of Properties
15550 Properties are contingently existing beings with multiple locations in space and time [Armstrong, by Lewis]
8. Modes of Existence / B. Properties / 11. Properties as Sets
10591 Logicians use 'property' and 'set' interchangeably, with little hanging on it [Shapiro]
10. Modality / B. Possibility / 5. Contingency
6215 'Contingent' means that the cause is unperceived, not that there is no cause [Hobbes]
10. Modality / C. Sources of Modality / 1. Sources of Necessity
4743 The truth-maker for a truth must necessitate that truth [Armstrong]
26. Natural Theory / C. Causation / 9. General Causation / d. Causal necessity
4798 In recent writings, Armstrong makes a direct identification of necessitation with causation [Armstrong, by Psillos]