Combining Philosophers

All the ideas for Eurytus, Wilfrid Hodges and Robert Merrihew Adams

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30 ideas

2. Reason / D. Definition / 7. Contextual Definition
The idea that groups of concepts could be 'implicitly defined' was abandoned [Hodges,W]
5. Theory of Logic / A. Overview of Logic / 1. Overview of Logic
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
Since first-order languages are complete, |= and |- have the same meaning [Hodges,W]
5. Theory of Logic / B. Logical Consequence / 4. Semantic Consequence |=
|= 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
A formula needs an 'interpretation' of its constants, and a 'valuation' of its variables [Hodges,W]
There are three different standard presentations of semantics [Hodges,W]
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
|= should be read as 'is a model for' or 'satisfies' [Hodges,W]
5. Theory of Logic / J. Model Theory in Logic / 1. Logical Models
Model theory studies formal or natural language-interpretation using set-theory [Hodges,W]
A 'structure' is an interpretation specifying objects and classes of quantification [Hodges,W]
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
Down Löwenheim-Skolem: if a countable language has a consistent theory, that has a countable model [Hodges,W]
Up Löwenheim-Skolem: if infinite models, then arbitrarily large models [Hodges,W]
5. Theory of Logic / K. Features of Logics / 6. Compactness
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
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
A 'set' is a mathematically well-behaved class [Hodges,W]
9. Objects / A. Existence of Objects / 5. Individuation / d. Individuation by haecceity
A 'thisness' is a thing's property of being identical with itself (not the possession of self-identity) [Adams,RM]
There are cases where mere qualities would not ensure an intrinsic identity [Adams,RM]
Adams says actual things have haecceities, but not things that only might exist [Adams,RM, by Stalnaker]
9. Objects / D. Essence of Objects / 9. Essence and Properties
Essences are taken to be qualitative properties [Adams,RM]
9. Objects / F. Identity among Objects / 7. Indiscernible Objects
If the universe was cyclical, totally indiscernible events might occur from time to time [Adams,RM]
Two events might be indiscernible yet distinct, if there was a universe cyclical in time [Adams,RM]
Black's two globes might be one globe in highly curved space [Adams,RM]
10. Modality / E. Possible worlds / 2. Nature of Possible Worlds / a. Nature of possible worlds
Are possible worlds just qualities, or do they include primitive identities as well? [Adams,RM]
10. Modality / E. Possible worlds / 2. Nature of Possible Worlds / b. Worlds as fictions
Possible worlds are world-stories, maximal descriptions of whole non-existent worlds [Adams,RM, by Molnar]
10. Modality / E. Possible worlds / 3. Transworld Objects / d. Haecceitism
Adams says anti-haecceitism reduces all thisness to suchness [Adams,RM, by Stalnaker]
Haecceitism may or may not involve some logical connection to essence [Adams,RM, by Mackie,P]
Moderate Haecceitism says transworld identities are primitive, but connected to qualities [Adams,RM]
19. Language / B. Reference / 3. Direct Reference / a. Direct reference
Direct reference is by proper names, or indexicals, or referential uses of descriptions [Adams,RM]
27. Natural Reality / G. Biology / 1. Biology
Eurytus showed that numbers underlie things by making pictures of creatures out of pebbles [Eurytus, by Aristotle]