Combining Texts

All the ideas for 'fragments/reports', 'Elusive Knowledge' and 'First-Order Logic'

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15 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]
11. Knowledge Aims / A. Knowledge / 4. Belief / a. Beliefs
12899 The timid student has knowledge without belief, lacking confidence in their correct answer [Lewis]
11. Knowledge Aims / B. Certain Knowledge / 3. Fallibilism
12897 To say S knows P, but cannot eliminate not-P, sounds like a contradiction [Lewis]
13. Knowledge Criteria / A. Justification Problems / 1. Justification / b. Need for justification
12898 Justification is neither sufficient nor necessary for knowledge [Lewis]
13. Knowledge Criteria / C. External Justification / 6. Contextual Justification / a. Contextualism
12895 Knowing is context-sensitive because the domain of quantification varies [Lewis, by Cohen,S]
19562 We have knowledge if alternatives are eliminated, but appropriate alternatives depend on context [Lewis, by Cohen,S]
26. Natural Theory / A. Speculations on Nature / 5. Infinite in Nature
1748 Archelaus was the first person to say that the universe is boundless [Archelaus, by Diog. Laertius]
27. Natural Reality / G. Biology / 3. Evolution
5989 Archelaus said life began in a primeval slime [Archelaus, by Schofield]