Combining Philosophers

All the ideas for Alan McMichael, Wilfrid Hodges and Mark Fisher

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24 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
A 'structure' is an interpretation specifying objects and classes of quantification [Hodges,W]
Model theory studies formal or natural language-interpretation using set-theory [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
Up Löwenheim-Skolem: if infinite models, then arbitrarily large models [Hodges,W]
Down Löwenheim-Skolem: if a countable language has a consistent theory, that has a countable model [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 / D. Essence of Objects / 3. Individual Essences
Only individuals have essences, so numbers (as a higher type based on classes) lack them [McMichael]
9. Objects / D. Essence of Objects / 9. Essence and Properties
Essences are the interesting necessary properties resulting from a thing's own peculiar nature [McMichael]
Maybe essential properties have to be intrinsic, as well as necessary? [McMichael]
9. Objects / D. Essence of Objects / 15. Against Essentialism
Essentialism is false, because it implies the existence of necessary singular propositions [McMichael]
24. Political Theory / C. Ruling a State / 4. Changing the State / a. Centralisation
Big central government only exists as a focus for anger - not to act [Fisher]
24. Political Theory / D. Ideologies / 11. Capitalism
It is hard to imagine the end of capitalism [Fisher]
25. Social Practice / E. Policies / 5. Education / a. Aims of education
Are students consumers or products of education? [Fisher]
26. Natural Theory / D. Laws of Nature / 5. Laws from Universals
Individuals enter into laws only through their general qualities and relations [McMichael]