Combining Texts

All the ideas for 'fragments/reports', 'First-Order Logic' and 'On the Individuation of Attributes'

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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]
8. Modes of Existence / B. Properties / 12. Denial of Properties
18439 Because things can share attributes, we cannot individuate attributes clearly [Quine]
8. Modes of Existence / E. Nominalism / 5. Class Nominalism
18442 You only know an attribute if you know what things have it [Quine]
9. Objects / A. Existence of Objects / 5. Individuation / a. Individuation
18441 No entity without identity (which requires a principle of individuation) [Quine]
9. Objects / F. Identity among Objects / 6. Identity between Objects
18440 Identity of physical objects is just being coextensive [Quine]
20. Action / B. Preliminaries of Action / 2. Willed Action / d. Weakness of will
22511 Some reasonings are stronger than we are [Philolaus]