Combining Philosophers

All the ideas for Hermarchus, Wilfrid Hodges and Michael Devitt

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32 ideas

2. Reason / D. Definition / 7. Contextual Definition
10476 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
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]
8. Modes of Existence / D. Universals / 1. Universals
8502 Realism doesn't explain 'a is F' any further by saying it is 'a has F-ness' [Devitt]
8. Modes of Existence / E. Nominalism / 1. Nominalism / b. Nominalism about universals
8503 The particular/universal distinction is unhelpful clutter; we should accept 'a is F' as basic [Devitt]
8. Modes of Existence / E. Nominalism / 1. Nominalism / c. Nominalism about abstracta
8501 Quineans take predication about objects as basic, not reference to properties they may have [Devitt]
9. Objects / D. Essence of Objects / 10. Essence as Species
17368 Essentialism concerns the nature of a group, not its category [Devitt]
17370 Things that gradually change, like species, can still have essences [Devitt]
12. Knowledge Sources / A. A Priori Knowledge / 4. A Priori as Necessities
9354 Why should necessities only be knowable a priori? That Hesperus is Phosporus is known empirically [Devitt]
19565 How could the mind have a link to the necessary character of reality? [Devitt]
12. Knowledge Sources / A. A Priori Knowledge / 9. A Priori from Concepts
9353 We explain away a priori knowledge, not as directly empirical, but as indirectly holistically empirical [Devitt]
12. Knowledge Sources / A. A Priori Knowledge / 11. Denying the A Priori
9356 The idea of the a priori is so obscure that it won't explain anything [Devitt]
19564 Some knowledge must be empirical; naturalism implies that all knowledge is like that [Devitt]
25. Social Practice / F. Life Issues / 6. Animal Rights
6005 Animals are dangerous and nourishing, and can't form contracts of justice [Hermarchus, by Sedley]
26. Natural Theory / B. Natural Kinds / 1. Natural Kinds
17371 Some kinds are very explanatory, but others less so, and some not at all [Devitt]
27. Natural Reality / G. Biology / 5. Species
17369 We name species as small to share properties, but large enough to yield generalisations [Devitt]
17367 Species are phenetic, biological, niche, or phylogenetic-cladistic [Devitt, by PG]
17372 The higher categories are not natural kinds, so the Linnaean hierarchy should be given up [Devitt]
17373 Species pluralism says there are several good accounts of what a species is [Devitt]