Combining Texts

All the ideas for 'fragments/reports', 'What are Sets and What are they For?' and 'Logical Necessity: Some Issues'

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25 ideas

1. Philosophy / B. History of Ideas / 2. Ancient Thought
1597 Thales was the first western thinker to believe the arché was intelligible [Roochnik on Thales]
4. Formal Logic / F. Set Theory ST / 3. Types of Set / b. Empty (Null) Set
14240 The empty set is something, not nothing! [Oliver/Smiley]
14239 The empty set is usually derived from Separation, but it also seems to need Infinity [Oliver/Smiley]
14241 We don't need the empty set to express non-existence, as there are other ways to do that [Oliver/Smiley]
14242 Maybe we can treat the empty set symbol as just meaning an empty term [Oliver/Smiley]
4. Formal Logic / F. Set Theory ST / 3. Types of Set / c. Unit (Singleton) Sets
14243 The unit set may be needed to express intersections that leave a single member [Oliver/Smiley]
5. Theory of Logic / G. Quantification / 6. Plural Quantification
14234 If you only refer to objects one at a time, you need sets in order to refer to a plurality [Oliver/Smiley]
14237 We can use plural language to refer to the set theory domain, to avoid calling it a 'set' [Oliver/Smiley]
5. Theory of Logic / I. Semantics of Logic / 3. Logical Truth
14245 Logical truths are true no matter what exists - but predicate calculus insists that something exists [Oliver/Smiley]
6. Mathematics / A. Nature of Mathematics / 4. Using Numbers / g. Applying mathematics
14246 If mathematics purely concerned mathematical objects, there would be no applied mathematics [Oliver/Smiley]
6. Mathematics / B. Foundations for Mathematics / 6. Mathematics as Set Theory / a. Mathematics is set theory
14247 Sets might either represent the numbers, or be the numbers, or replace the numbers [Oliver/Smiley]
10. Modality / A. Necessity / 6. Logical Necessity
12184 Logical necessity overrules all other necessities [McFetridge]
15083 The fundamental case of logical necessity is the valid conclusion of an inference [McFetridge, by Hale]
15084 In the McFetridge view, logical necessity means a consequent must be true if the antecedent is [McFetridge, by Hale]
12180 Logical necessity requires that a valid argument be necessary [McFetridge]
12181 Traditionally, logical necessity is the strongest, and entails any other necessities [McFetridge]
12183 It is only logical necessity if there is absolutely no sense in which it could be false [McFetridge]
12192 The mark of logical necessity is deduction from any suppositions whatever [McFetridge]
10. Modality / B. Possibility / 2. Epistemic possibility
12182 We assert epistemic possibility without commitment to logical possibility [McFetridge]
10. Modality / C. Sources of Modality / 1. Sources of Necessity
12187 Objectual modal realists believe in possible worlds; non-objectual ones rest it on the actual world [McFetridge]
10. Modality / C. Sources of Modality / 5. Modality from Actuality
3013 Nothing is stronger than necessity, which rules everything [Thales, by Diog. Laertius]
12186 Modal realists hold that necessities and possibilities are part of the totality of facts [McFetridge]
26. Natural Theory / A. Speculations on Nature / 6. Early Matter Theories / c. Ultimate substances
1494 Thales said water is the first principle, perhaps from observing that food is moist [Thales, by Aristotle]
27. Natural Reality / A. Classical Physics / 1. Mechanics / a. Explaining movement
1713 Thales must have thought soul causes movement, since he thought magnets have soul [Thales, by Aristotle]
29. Religion / A. Polytheistic Religion / 2. Greek Polytheism
1742 Thales said the gods know our wrong thoughts as well as our evil actions [Thales, by Diog. Laertius]