Combining Philosophers

All the ideas for William S. Jevons, Wilfrid Hodges and Achille Varzi

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28 ideas

2. Reason / D. Definition / 7. Contextual Definition
10476 The idea that groups of concepts could be 'implicitly defined' was abandoned [Hodges,W]
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 / 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 / 1. Overview of Logic
10282 Logic is the study of sound argument, or of certain artificial languages (or applying the latter to the former) [Hodges,W]
5. Theory of Logic / A. Overview of Logic / 5. First-Order Logic
10478 Since first-order languages are complete, |= and |- have the same meaning [Hodges,W]
5. Theory of Logic / B. Logical Consequence / 4. Semantic Consequence |=
10477 |= in model-theory means 'logical consequence' - it holds in all models [Hodges,W]
5. Theory of Logic / I. Semantics of Logic / 1. Semantics of Logic
10283 A formula needs an 'interpretation' of its constants, and a 'valuation' of its variables [Hodges,W]
10284 There are three different standard presentations of semantics [Hodges,W]
10285 I |= φ means that the formula φ is true in the interpretation I [Hodges,W]
5. Theory of Logic / I. Semantics of Logic / 4. Satisfaction
10474 |= should be read as 'is a model for' or 'satisfies' [Hodges,W]
5. Theory of Logic / J. Model Theory in Logic / 1. Logical Models
10473 Model theory studies formal or natural language-interpretation using set-theory [Hodges,W]
10475 A 'structure' is an interpretation specifying objects and classes of quantification [Hodges,W]
10481 Models in model theory are structures, not sets of descriptions [Hodges,W]
5. Theory of Logic / J. Model Theory in Logic / 3. Löwenheim-Skolem Theorems
10288 Down Löwenheim-Skolem: if a countable language has a consistent theory, that has a countable model [Hodges,W]
10289 Up Löwenheim-Skolem: if infinite models, then arbitrarily large models [Hodges,W]
5. Theory of Logic / K. Features of Logics / 6. Compactness
10287 If a first-order theory entails a sentence, there is a finite subset of the theory which entails it [Hodges,W]
6. Mathematics / A. Nature of Mathematics / 5. The Infinite / i. Cardinal infinity
10480 First-order logic can't discriminate between one infinite cardinal and another [Hodges,W]
6. Mathematics / B. Foundations for Mathematics / 6. Mathematics as Set Theory / a. Mathematics is set theory
10286 A 'set' is a mathematically well-behaved class [Hodges,W]
6. Mathematics / C. Sources of Mathematics / 6. Logicism / a. Early logicism
8628 I hold that algebra and number are developments of logic [Jevons]
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]