Combining Texts

All the ideas for 'Letters to Bentley', 'First-Order Logic' and 'Rationale and Maxims in Study of Concepts'

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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 / A. Nature of Mathematics / 3. Nature of Numbers / a. Numbers
13152 We can talk of 'innumerable number', about the infinite points on a line [Newton]
6. Mathematics / A. Nature of Mathematics / 5. The Infinite / a. The Infinite
13151 Not all infinites are equal [Newton]
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]
18. Thought / D. Concepts / 3. Ontology of Concepts / a. Concepts as representations
11127 If concepts just are mental representations, what of concepts we may never acquire? [Peacocke]
26. Natural Theory / D. Laws of Nature / 1. Laws of Nature
15863 The principles of my treatise are designed to fit with a belief in God [Newton]
26. Natural Theory / D. Laws of Nature / 4. Regularities / a. Regularity theory
8340 I do not pretend to know the cause of gravity [Newton]
26. Natural Theory / D. Laws of Nature / 8. Scientific Essentialism / e. Anti scientific essentialism
13150 The motions of the planets could only derive from an intelligent agent [Newton]
12178 That gravity should be innate and essential to matter is absurd [Newton]