Combining Texts

All the ideas for 'Truth-making without Truth-makers', 'Elements of Set Theory' and 'Absolute Necessities'

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17 ideas

4. Formal Logic / F. Set Theory ST / 2. Mechanics of Set Theory / b. Terminology of ST
13201 ∈ says the whole set is in the other; ⊆ says the members of the subset are in the other [Enderton]
13204 The 'ordered pair' <x,y> is defined to be {{x}, {x,y}} [Enderton]
13206 A 'linear or total ordering' must be transitive and satisfy trichotomy [Enderton]
4. Formal Logic / F. Set Theory ST / 3. Types of Set / b. Empty (Null) Set
13200 Note that {Φ} =/= Φ, because Φ ∈ {Φ} but Φ ∉ Φ [Enderton]
13199 The empty set may look pointless, but many sets can be constructed from it [Enderton]
4. Formal Logic / F. Set Theory ST / 3. Types of Set / c. Unit (Singleton) Sets
13203 The singleton is defined using the pairing axiom (as {x,x}) [Enderton]
4. Formal Logic / F. Set Theory ST / 4. Axioms for Sets / h. Axiom of Replacement VII
13202 Fraenkel added Replacement, to give a theory of ordinal numbers [Enderton]
4. Formal Logic / F. Set Theory ST / 4. Axioms for Sets / j. Axiom of Choice IX
13205 We can only define functions if Choice tells us which items are involved [Enderton]
10. Modality / A. Necessity / 2. Nature of Necessity
15086 Absolute necessity might be achievable either logically or metaphysically [Hale]
10. Modality / A. Necessity / 3. Types of Necessity
8261 Maybe not-p is logically possible, but p is metaphysically necessary, so the latter is not absolute [Hale]
15081 A strong necessity entails a weaker one, but not conversely; possibilities go the other way [Hale]
15080 'Relative' necessity is just a logical consequence of some statements ('strong' if they are all true) [Hale]
10. Modality / A. Necessity / 5. Metaphysical Necessity
15082 Metaphysical necessity says there is no possibility of falsehood [Hale]
10. Modality / A. Necessity / 6. Logical Necessity
15085 'Broadly' logical necessities are derived (in a structure) entirely from the concepts [Hale]
15088 Logical necessities are true in virtue of the nature of all logical concepts [Hale]
10. Modality / C. Sources of Modality / 4. Necessity from Concepts
15087 Conceptual necessities are made true by all concepts [Hale]
14. Science / D. Explanation / 2. Types of Explanation / a. Types of explanation
17319 There are 'conceptual' explanations, with their direction depending on complexity [Schnieder]