Combining Texts

All the ideas for 'fragments/reports', 'First-Order Logic' and 'Empty Names'

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14 ideas

5. Theory of Logic / A. Overview of Logic / 1. Overview of Logic
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 / F. Referring in Logic / 1. Naming / a. Names
Semantic theory should specify when an act of naming is successful [Sawyer]
5. Theory of Logic / F. Referring in Logic / 1. Naming / c. Names as referential
Millians say a name just means its object [Sawyer]
5. Theory of Logic / F. Referring in Logic / 1. Naming / e. Empty names
Sentences with empty names can be understood, be co-referential, and even be true [Sawyer]
Frege's compositional account of truth-vaues makes 'Pegasus doesn't exist' neither true nor false [Sawyer]
5. Theory of Logic / F. Referring in Logic / 2. Descriptions / c. Theory of definite descriptions
Definites descriptions don't solve the empty names problem, because the properties may not exist [Sawyer]
5. Theory of Logic / I. Semantics of Logic / 1. Semantics of Logic
A formula needs an 'interpretation' of its constants, and a 'valuation' of its variables [Hodges,W]
There are three different standard presentations of semantics [Hodges,W]
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
Down Löwenheim-Skolem: if a countable language has a consistent theory, that has a countable model [Hodges,W]
Up Löwenheim-Skolem: if infinite models, then arbitrarily large models [Hodges,W]
5. Theory of Logic / K. Features of Logics / 6. Compactness
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
A 'set' is a mathematically well-behaved class [Hodges,W]
21. Aesthetics / C. Artistic Issues / 7. Art and Morality
Musical performance can reveal a range of virtues [Damon of Ath.]