Combining Texts

All the ideas for 'teaching', 'A Tour through Mathematical Logic' and 'The Mysterious Flame'

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38 ideas

1. Philosophy / A. Wisdom / 1. Nature of Wisdom
Speak the truth, for this alone deifies man [Pythagoras, by Porphyry]
1. Philosophy / B. History of Ideas / 2. Ancient Thought
Pythagoras discovered the numerical relation of sounds on a string [Pythagoras, by Diog. Laertius]
1. Philosophy / E. Nature of Metaphysics / 5. Metaphysics beyond Science
Philosophy is a magnificent failure in its attempt to overstep the limits of our knowledge [McGinn]
4. Formal Logic / B. Propositional Logic PL / 2. Tools of Propositional Logic / b. Terminology of PL
A 'tautology' must include connectives [Wolf,RS]
4. Formal Logic / B. Propositional Logic PL / 2. Tools of Propositional Logic / c. Derivation rules of PL
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 ∀
Universal Generalization: If we prove P(x) with no special assumptions, we can conclude ∀xP(x) [Wolf,RS]
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 ∃
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
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
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
In first-order logic syntactic and semantic consequence (|- and |=) nicely coincide [Wolf,RS]
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 / E. Structures of Logic / 1. Logical Form
Thoughts have a dual aspect: as they seem to introspection, and their underlying logical reality [McGinn]
5. Theory of Logic / J. Model Theory in Logic / 1. Logical Models
Model theory reveals the structures of mathematics [Wolf,RS]
Model theory 'structures' have a 'universe', some 'relations', some 'functions', and some 'constants' [Wolf,RS]
Model theory uses sets to show that mathematical deduction fits mathematical truth [Wolf,RS]
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
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
The LST Theorem is a serious limitation of first-order logic [Wolf,RS]
5. Theory of Logic / K. Features of Logics / 4. Completeness
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
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
An ordinal is an equivalence class of well-orderings, or a transitive set whose members are transitive [Wolf,RS]
6. Mathematics / A. Nature of Mathematics / 3. Nature of Numbers / m. One
For Pythagoreans 'one' is not a number, but the foundation of numbers [Pythagoras, by Watson]
6. Mathematics / B. Foundations for Mathematics / 6. Mathematics as Set Theory / a. Mathematics is set theory
Modern mathematics has unified all of its objects within set theory [Wolf,RS]
15. Nature of Minds / C. Capacities of Minds / 1. Faculties
Mental modules for language, social, action, theory, space, emotion [McGinn]
16. Persons / F. Free Will / 1. Nature of Free Will
Free will is mental causation in action [McGinn]
17. Mind and Body / A. Mind-Body Dualism / 3. Panpsychism
Brains aren't made of anything special, suggesting panpsychism [McGinn]
17. Mind and Body / D. Property Dualism / 6. Mysterianism
Examining mind sees no brain; examining brain sees no mind [McGinn]
19. Language / C. Assigning Meanings / 6. Truth-Conditions Semantics
There is information if there are symbols which refer, and which can combine into a truth or falsehood [McGinn]
22. Metaethics / B. Value / 2. Values / d. Health
Pythagoras taught that virtue is harmony, and health, and universal good, and God [Pythagoras, by Diog. Laertius]
23. Ethics / C. Virtue Theory / 3. Virtues / c. Justice
For Pythagoreans, justice is simply treating all people the same [Pythagoras, by Aristotle]
26. Natural Theory / A. Speculations on Nature / 4. Mathematical Nature
When musical harmony and rhythm were discovered, similar features were seen in bodily movement [Pythagoras, by Plato]
Pythagoreans define timeliness, justice and marriage in terms of numbers [Pythagoras, by Aristotle]
Pythagoreans think mathematical principles are the principles of all of nature [Pythagoras, by Aristotle]
Pythagoreans say things imitate numbers, but Plato says things participate in numbers [Pythagoras, by Aristotle]
For Pythagoreans the entire universe is made of numbers [Pythagoras, by Aristotle]
26. Natural Theory / C. Causation / 4. Naturalised causation
Causation in the material world is energy-transfer, of motion, electricity or gravity [McGinn]
29. Religion / D. Religious Issues / 2. Immortality / a. Immortality
The modern idea of an immortal soul was largely created by Pythagoras [Pythagoras, by Watson]