Combining Texts

All the ideas for 'works', 'The Limits of Communitarianism' and 'A Tour through Mathematical Logic'

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31 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]
12. Knowledge Sources / B. Perception / 1. Perception
22167 Our images of bodies are not produced by the bodies, but by our own minds [Augustine, by Aquinas]
12. Knowledge Sources / C. Rationalism / 1. Rationalism
22117 Our minds grasp reality by direct illumination (rather than abstraction from experience) [Augustine, by Matthews]
20. Action / B. Preliminaries of Action / 2. Willed Action / a. Will to Act
22118 Augustine created the modern concept of the will [Augustine, by Matthews]
22. Metaethics / B. Value / 2. Values / g. Love
4348 Love, and do what you will [Augustine]
22. Metaethics / C. The Good / 1. Goodness / b. Types of good
7821 Pagans produced three hundred definitions of the highest good [Augustine, by Grayling]
23. Ethics / D. Deontological Ethics / 2. Duty
22119 Augustine said (unusually) that 'ought' does not imply 'can' [Augustine, by Matthews]
24. Political Theory / D. Ideologies / 7. Communitarianism / b. Against communitarianism
22265 I can't defend the view that the majority values of a community are thereby right [Sandel]
25. Social Practice / A. Freedoms / 3. Free speech
22268 If persons define themselves by a group membership, insults to that group are a real harm [Sandel]
22267 In the liberal view an insult to my group doesn't hurt me, since I'm defined by choices not groups [Sandel]
25. Social Practice / E. Policies / 2. Religion in Society
22266 The case for religious liberty depends on the religion contributing to a morally good life [Sandel]
29. Religion / B. Monotheistic Religion / 4. Christianity / d. Heresy
22116 Augustine identified Donatism, Pelagianism and Manicheism as the main heresies [Augustine, by Matthews]
29. Religion / D. Religious Issues / 3. Problem of Evil / b. Human Evil
19338 Augustine said evil does not really exist, and evil is a limitation in goodness [Augustine, by Perkins]