Combining Texts

All the ideas for 'reports', 'fragments/reports' and 'Introduction to the Theory of Logic'

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32 ideas

4. Formal Logic / F. Set Theory ST / 1. Set Theory
10888 Sets can be defined by 'enumeration', or by 'abstraction' (based on a property) [Zalabardo]
4. Formal Logic / F. Set Theory ST / 2. Mechanics of Set Theory / b. Terminology of ST
10889 The 'Cartesian Product' of two sets relates them by pairing every element with every element [Zalabardo]
10890 A 'partial ordering' is reflexive, antisymmetric and transitive [Zalabardo]
4. Formal Logic / F. Set Theory ST / 4. Axioms for Sets / a. Axioms for sets
10886 Determinacy: an object is either in a set, or it isn't [Zalabardo]
4. Formal Logic / F. Set Theory ST / 4. Axioms for Sets / l. Axiom of Specification
10887 Specification: Determinate totals of objects always make a set [Zalabardo]
5. Theory of Logic / A. Overview of Logic / 5. First-Order Logic
10897 A first-order 'sentence' is a formula with no free variables [Zalabardo]
5. Theory of Logic / B. Logical Consequence / 4. Semantic Consequence |=
10893 Γ |= φ for sentences if φ is true when all of Γ is true [Zalabardo]
10899 Γ |= φ if φ is true when all of Γ is true, for all structures and interpretations [Zalabardo]
5. Theory of Logic / E. Structures of Logic / 2. Logical Connectives / b. Basic connectives
10896 Propositional logic just needs ¬, and one of ∧, ∨ and → [Zalabardo]
5. Theory of Logic / I. Semantics of Logic / 1. Semantics of Logic
10898 The semantics shows how truth values depend on instantiations of properties and relations [Zalabardo]
10902 We can do semantics by looking at given propositions, or by building new ones [Zalabardo]
5. Theory of Logic / I. Semantics of Logic / 2. Formal Truth
10892 We make a truth assignment to T and F, which may be true and false, but merely differ from one another [Zalabardo]
5. Theory of Logic / I. Semantics of Logic / 3. Logical Truth
10895 'Logically true' (|= φ) is true for every truth-assignment [Zalabardo]
10900 Logically true sentences are true in all structures [Zalabardo]
5. Theory of Logic / I. Semantics of Logic / 4. Satisfaction
10901 Some formulas are 'satisfiable' if there is a structure and interpretation that makes them true [Zalabardo]
10894 A sentence-set is 'satisfiable' if at least one truth-assignment makes them all true [Zalabardo]
5. Theory of Logic / J. Model Theory in Logic / 1. Logical Models
10903 A structure models a sentence if it is true in the model, and a set of sentences if they are all true in the model [Zalabardo]
6. Mathematics / B. Foundations for Mathematics / 4. Axioms for Number / f. Mathematical induction
10891 If a set is defined by induction, then proof by induction can be applied to it [Zalabardo]
20. Action / C. Motives for Action / 3. Acting on Reason / b. Intellectualism
7352 Jesus said learning was unnecessary, and only the spirit of the Law was needed [Jesus, by Johnson,P]
22. Metaethics / B. Value / 2. Values / g. Love
6289 Love your enemies [Jesus]
6292 Love thy neighbour as thyself [Jesus]
23. Ethics / B. Contract Ethics / 2. Golden Rule
5356 Treat others as you would have them treat you [Jesus]
23. Ethics / B. Contract Ethics / 4. Value of Authority
6286 Blessed are the merciful: for they shall obtain mercy [Jesus]
23. Ethics / C. Virtue Theory / 2. Elements of Virtue Theory / c. Motivation for virtue
6290 Except ye become as little children, ye shall not enter heaven [Jesus]
23. Ethics / C. Virtue Theory / 2. Elements of Virtue Theory / h. Right feelings
6287 If you lust after a woman, you have committed adultery [Jesus]
23. Ethics / C. Virtue Theory / 3. Virtues / a. Virtues
6285 Blessed are the meek; for they shall inherit the earth [Jesus]
23. Ethics / C. Virtue Theory / 3. Virtues / c. Justice
6288 Don't resist evil, but turn the other cheek [Jesus]
23. Ethics / C. Virtue Theory / 4. External Goods / c. Wealth
6293 It is almost impossible for the rich to go to heaven [Jesus]
25. Social Practice / E. Policies / 5. Education / b. Education principles
13304 Learned men gain more in one day than others do in a lifetime [Posidonius]
27. Natural Reality / D. Time / 1. Nature of Time / d. Time as measure
20820 Time is an interval of motion, or the measure of speed [Posidonius, by Stobaeus]
28. God / A. Divine Nature / 6. Divine Morality / c. God is the good
6291 No one is good except God [Jesus]
29. Religion / B. Monotheistic Religion / 4. Christianity / a. Christianity
7351 Jesus turned the ideas of Hillel into a theology reduced to its moral elements [Jesus, by Johnson,P]