Combining Texts

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

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19 ideas

1. Philosophy / C. History of Philosophy / 2. Ancient Philosophy / b. Pre-Socratic philosophy
5988 Anaximander produced the first philosophy book (and maybe the first book) [Anaximander, by Bodnár]
2. Reason / B. Laws of Thought / 2. Sufficient Reason
1496 The earth is stationary, because it is in the centre, and has no more reason to move one way than another [Anaximander, by Aristotle]
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
10289 Up Löwenheim-Skolem: if infinite models, then arbitrarily large models [Hodges,W]
10288 Down Löwenheim-Skolem: if a countable language has a consistent theory, that has a countable model [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 / A. Nature of Existence / 1. Nature of Existence
14874 Anaximander saw the contradiction in the world - that its own qualities destroy it [Anaximander, by Nietzsche]
19. Language / A. Nature of Meaning / 6. Meaning as Use
20949 Study the use of words, not their origins [Herder]
22. Metaethics / B. Value / 1. Nature of Value / f. Ultimate value
7669 We cannot attain all the ideals of every culture, so there cannot be a perfect life [Herder, by Berlin]
24. Political Theory / D. Ideologies / 7. Communitarianism / a. Communitarianism
7668 Herder invented the idea of being rooted in (or cut off from) a home or a group [Herder, by Berlin]
26. Natural Theory / A. Speculations on Nature / 6. Early Matter Theories / d. The unlimited
13222 The Boundless cannot exist on its own, and must have something contrary to it [Aristotle on Anaximander]
1495 Anaximander introduced the idea that the first principle and element of things was the Boundless [Anaximander, by Simplicius]
404 Things begin and end in the Unlimited, and are balanced over time according to justice [Anaximander]
405 The essential nature, whatever it is, of the non-limited is everlasting and ageless [Anaximander]
27. Natural Reality / E. Cosmology / 2. Eternal Universe
1746 The parts of all things are susceptible to change, but the whole is unchangeable [Anaximander, by Diog. Laertius]