Combining Texts

All the ideas for 'Saundaranandakavya', 'First-Order Logic' and 'The Nature of Mathematics'

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19 ideas

1. Philosophy / D. Nature of Philosophy / 2. Invocation to Philosophy
7910 Pursue truth with the urgency of someone whose clothes are on fire [Ashvaghosha]
1. Philosophy / G. Scientific Philosophy / 3. Scientism
14782 Philosophy is an experimental science, resting on common experience [Peirce]
2. Reason / B. Laws of Thought / 3. Non-Contradiction
14787 Self-contradiction doesn't reveal impossibility; it is inductive impossibility which reveals self-contradiction [Peirce]
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 / C. Ontology of Logic / 3. If-Thenism
14783 Logic, unlike mathematics, is not hypothetical; it asserts categorical ends from hypothetical means [Peirce]
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]
6. Mathematics / C. Sources of Mathematics / 6. Logicism / a. Early logicism
14788 Mathematics is close to logic, but is even more abstract [Peirce]
10. Modality / B. Possibility / 1. Possibility
14786 Some logical possibility concerns single propositions, but there is also compatibility between propositions [Peirce]
12. Knowledge Sources / D. Empiricism / 1. Empiricism
14789 Experience is indeed our only source of knowledge, provided we include inner experience [Peirce]
12. Knowledge Sources / D. Empiricism / 5. Empiricism Critique
14785 The world is one of experience, but experiences are always located among our ideas [Peirce]
22. Metaethics / A. Ethics Foundations / 1. Nature of Ethics / b. Defining ethics
14784 Ethics is the science of aims [Peirce]
29. Religion / C. Spiritual Disciplines / 3. Buddhism
7909 The Eightfold Path concerns morality, wisdom, and tranquillity [Ashvaghosha]
29. Religion / D. Religious Issues / 2. Immortality / d. Heaven
7908 At the end of a saint, he is not located in space, but just ceases to be disturbed [Ashvaghosha]