Combining Texts

All the ideas for 'Works of Love', 'On Human Nature' and 'A Tour through Mathematical Logic'

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32 ideas

4. Formal Logic / B. Propositional Logic PL / 2. Tools of Propositional Logic / b. Terminology of PL
13520 A 'tautology' must include connectives [Wolf,RS]
4. Formal Logic / B. Propositional Logic PL / 2. Tools of Propositional Logic / c. Derivation rules of PL
13524 Deduction Theorem: T∪{P}|-Q, then T|-(P→Q), which justifies Conditional Proof [Wolf,RS]
4. Formal Logic / C. Predicate Calculus PC / 2. Tools of Predicate Calculus / d. Universal quantifier ∀
13522 Universal Generalization: If we prove P(x) with no special assumptions, we can conclude ∀xP(x) [Wolf,RS]
13521 Universal Specification: ∀xP(x) implies P(t). True for all? Then true for an instance [Wolf,RS]
4. Formal Logic / C. Predicate Calculus PC / 2. Tools of Predicate Calculus / e. Existential quantifier ∃
13523 Existential Generalization (or 'proof by example'): if we can say P(t), then we can say something is P [Wolf,RS]
4. Formal Logic / F. Set Theory ST / 4. Axioms for Sets / e. Axiom of the Empty Set IV
13529 Empty Set: ∃x∀y ¬(y∈x). The unique empty set exists [Wolf,RS]
4. Formal Logic / F. Set Theory ST / 4. Axioms for Sets / n. Axiom of Comprehension
13526 Comprehension Axiom: if a collection is clearly specified, it is a set [Wolf,RS]
5. Theory of Logic / A. Overview of Logic / 5. First-Order Logic
13534 In first-order logic syntactic and semantic consequence (|- and |=) nicely coincide [Wolf,RS]
13535 First-order logic is weakly complete (valid sentences are provable); we can't prove every sentence or its negation [Wolf,RS]
5. Theory of Logic / J. Model Theory in Logic / 1. Logical Models
13531 Model theory reveals the structures of mathematics [Wolf,RS]
13532 Model theory 'structures' have a 'universe', some 'relations', some 'functions', and some 'constants' [Wolf,RS]
13519 Model theory uses sets to show that mathematical deduction fits mathematical truth [Wolf,RS]
13533 First-order model theory rests on completeness, compactness, and the Löwenheim-Skolem-Tarski theorem [Wolf,RS]
5. Theory of Logic / J. Model Theory in Logic / 2. Isomorphisms
13537 An 'isomorphism' is a bijection that preserves all structural components [Wolf,RS]
5. Theory of Logic / J. Model Theory in Logic / 3. Löwenheim-Skolem Theorems
13539 The LST Theorem is a serious limitation of first-order logic [Wolf,RS]
5. Theory of Logic / K. Features of Logics / 4. Completeness
13538 If a theory is complete, only a more powerful language can strengthen it [Wolf,RS]
5. Theory of Logic / K. Features of Logics / 10. Monotonicity
13525 Most deductive logic (unlike ordinary reasoning) is 'monotonic' - we don't retract after new givens [Wolf,RS]
6. Mathematics / A. Nature of Mathematics / 3. Nature of Numbers / e. Ordinal numbers
13530 An ordinal is an equivalence class of well-orderings, or a transitive set whose members are transitive [Wolf,RS]
6. Mathematics / B. Foundations for Mathematics / 6. Mathematics as Set Theory / a. Mathematics is set theory
13518 Modern mathematics has unified all of its objects within set theory [Wolf,RS]
7. Existence / C. Structure of Existence / 3. Levels of Reality
5311 If observation goes up a level, we expect the laws of the lower level to remain in force [Wilson,EO]
8. Modes of Existence / D. Universals / 5. Universals as Concepts
5312 A child first sees objects as distinct, and later as members of groups [Wilson,EO]
11. Knowledge Aims / A. Knowledge / 4. Belief / a. Beliefs
5309 Beliefs are really enabling mechanisms for survival [Wilson,EO]
22. Metaethics / A. Ethics Foundations / 1. Nature of Ethics / d. Ethical theory
5310 Philosophers study the consequences of ethics instead of its origins [Wilson,EO]
22. Metaethics / A. Ethics Foundations / 2. Source of Ethics / e. Human nature
5313 The rules of human decision-making converge and overlap in a 'human nature' [Wilson,EO]
22. Metaethics / B. Value / 2. Values / f. Altruism
5316 We undermine altruism by rewarding it, but we reward it to encourage it [Wilson,EO]
5318 Pure hard-core altruism based on kin selection is the enemy of civilisation [Wilson,EO]
22. Metaethics / B. Value / 2. Values / g. Love
15998 Perfect love is not in spite of imperfections; the imperfections must be loved as well [Kierkegaard]
23. Ethics / B. Contract Ethics / 1. Contractarianism
5317 The actor is most convincing who believes that his performance is real [Wilson,EO]
26. Natural Theory / A. Speculations on Nature / 2. Natural Purpose / c. Purpose denied
5308 The only human purpose is that created by our genetic history [Wilson,EO]
27. Natural Reality / G. Biology / 3. Evolution
5314 Cultural evolution is Lamarckian and fast, biological evolution is Darwinian and slow [Wilson,EO]
5315 Over 99 percent of human evolution has been in the hunter-gatherer phase [Wilson,EO]
29. Religion / D. Religious Issues / 1. Religious Commitment / a. Religious Belief
5320 It is estimated that mankind has produced 100,000 religions [Wilson,EO]