Combining Texts

All the ideas for 'Issues of Pragmaticism', 'First-Order Logic' and 'Resurrecting Biological Essentialism'

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13 ideas

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 / 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 / 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 / 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]
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]
19. Language / A. Nature of Meaning / 1. Meaning
19087 The meaning or purport of a symbol is all the rational conduct it would lead to [Peirce]
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]