Combining Texts

All the ideas for 'Ethics of Ambiguity', 'First-Order Logic' and 'The Blue and Brown Notebooks'

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11 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]
16. Persons / D. Continuity of the Self / 3. Reference of 'I'
22419 'I' is a subject in 'I am in pain' and an object in 'I am bleeding' [Wittgenstein, by McGinn]
19. Language / F. Communication / 6. Interpreting Language / b. Indeterminate translation
6318 The doctrine of indeterminacy of translation seems implied by the later Wittgenstein [Wittgenstein, by Quine]
23. Ethics / F. Existentialism / 3. Angst
20761 If existence is absurd it can never have a meaning [Beauvoir]