Combining Texts

All the ideas for 'poems', 'Nominalism' and 'First-Order Logic'

expand these ideas     |    start again     |     specify just one area for these texts

13 ideas

4. Formal Logic / F. Set Theory ST / 3. Types of Set / c. Unit (Singleton) Sets
8956 What is a singleton set, if a set is meant to be a collection of objects? [Szabó]
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]
7. Existence / C. Structure of Existence / 7. Abstract/Concrete / a. Abstract/concrete
8953 Abstract entities don't depend on their concrete entities ...but maybe on the totality of concrete things [Szabó]
15. Nature of Minds / C. Capacities of Minds / 3. Abstraction by mind
8954 Geometrical circles cannot identify a circular paint patch, presumably because they lack something [Szabó]
18. Thought / E. Abstraction / 5. Abstracta by Negation
8955 Abstractions are imperceptible, non-causal, and non-spatiotemporal (the third explaining the others) [Szabó]
22. Metaethics / A. Ethics Foundations / 2. Source of Ethics / j. Ethics by convention
6017 Nomos is king [Pindar]