Combining Texts

All the ideas for 'Necessity and Non-Existence', 'Letters' and 'What Required for Foundation for Maths?'

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51 ideas

2. Reason / D. Definition / 2. Aims of Definition
Definitions make our intuitions mathematically useful [Mayberry]
2. Reason / E. Argument / 6. Conclusive Proof
Proof shows that it is true, but also why it must be true [Mayberry]
3. Truth / B. Truthmakers / 5. What Makes Truths / a. What makes truths
Some sentences depend for their truth on worldly circumstances, and others do not [Fine,K]
4. Formal Logic / F. Set Theory ST / 4. Axioms for Sets / a. Axioms for sets
Set theory can't be axiomatic, because it is needed to express the very notion of axiomatisation [Mayberry]
There is a semi-categorical axiomatisation of set-theory [Mayberry]
4. Formal Logic / F. Set Theory ST / 4. Axioms for Sets / f. Axiom of Infinity V
The misnamed Axiom of Infinity says the natural numbers are finite in size [Mayberry]
4. Formal Logic / F. Set Theory ST / 5. Conceptions of Set / e. Iterative sets
The set hierarchy doesn't rely on the dubious notion of 'generating' them [Mayberry]
4. Formal Logic / F. Set Theory ST / 5. Conceptions of Set / f. Limitation of Size
Limitation of size is part of the very conception of a set [Mayberry]
5. Theory of Logic / A. Overview of Logic / 2. History of Logic
The mainstream of modern logic sees it as a branch of mathematics [Mayberry]
5. Theory of Logic / A. Overview of Logic / 5. First-Order Logic
First-order logic only has its main theorems because it is so weak [Mayberry]
5. Theory of Logic / A. Overview of Logic / 7. Second-Order Logic
Only second-order logic can capture mathematical structure up to isomorphism [Mayberry]
5. Theory of Logic / G. Quantification / 2. Domain of Quantification
Big logic has one fixed domain, but standard logic has a domain for each interpretation [Mayberry]
5. Theory of Logic / J. Model Theory in Logic / 3. Löwenheim-Skolem Theorems
No Löwenheim-Skolem logic can axiomatise real analysis [Mayberry]
5. Theory of Logic / K. Features of Logics / 1. Axiomatisation
'Classificatory' axioms aim at revealing similarity in morphology of structures [Mayberry]
Axiomatiation relies on isomorphic structures being essentially the same [Mayberry]
'Eliminatory' axioms get rid of traditional ideal and abstract objects [Mayberry]
5. Theory of Logic / K. Features of Logics / 6. Compactness
No logic which can axiomatise arithmetic can be compact or complete [Mayberry]
6. Mathematics / A. Nature of Mathematics / 3. Nature of Numbers / g. Real numbers
Real numbers can be eliminated, by axiom systems for complete ordered fields [Mayberry]
6. Mathematics / A. Nature of Mathematics / 4. Using Numbers / b. Quantity
Greek quantities were concrete, and ratio and proportion were their science [Mayberry]
Real numbers were invented, as objects, to simplify and generalise 'quantity' [Mayberry]
6. Mathematics / A. Nature of Mathematics / 5. The Infinite / a. The Infinite
Cantor's infinite is an absolute, of all the sets or all the ordinal numbers [Mayberry]
Cantor extended the finite (rather than 'taming the infinite') [Mayberry]
6. Mathematics / B. Foundations for Mathematics / 1. Foundations for Mathematics
If proof and definition are central, then mathematics needs and possesses foundations [Mayberry]
The ultimate principles and concepts of mathematics are presumed, or grasped directly [Mayberry]
Foundations need concepts, definition rules, premises, and proof rules [Mayberry]
Axiom theories can't give foundations for mathematics - that's using axioms to explain axioms [Mayberry]
6. Mathematics / B. Foundations for Mathematics / 4. Axioms for Number / d. Peano arithmetic
1st-order PA is only interesting because of results which use 2nd-order PA [Mayberry]
6. Mathematics / B. Foundations for Mathematics / 4. Axioms for Number / g. Incompleteness of Arithmetic
It is only 2nd-order isomorphism which suggested first-order PA completeness [Mayberry]
6. Mathematics / B. Foundations for Mathematics / 6. Mathematics as Set Theory / a. Mathematics is set theory
Set theory is not just first-order ZF, because that is inadequate for mathematics [Mayberry]
We don't translate mathematics into set theory, because it comes embodied in that way [Mayberry]
Set theory is not just another axiomatised part of mathematics [Mayberry]
7. Existence / A. Nature of Existence / 2. Types of Existence
There are levels of existence, as well as reality; objects exist at the lowest level in which they can function [Fine,K]
7. Existence / D. Theories of Reality / 3. Reality
Bottom level facts are subject to time and world, middle to world but not time, and top to neither [Fine,K]
7. Existence / D. Theories of Reality / 8. Facts / b. Types of fact
Tensed and tenseless sentences state two sorts of fact, which belong to two different 'realms' of reality [Fine,K]
9. Objects / A. Existence of Objects / 2. Abstract Objects / a. Nature of abstracta
Real numbers as abstracted objects are now treated as complete ordered fields [Mayberry]
9. Objects / B. Unity of Objects / 1. Unifying an Object / a. Intrinsic unification
Modal features are not part of entities, because they are accounted for by the entity [Fine,K]
9. Objects / D. Essence of Objects / 6. Essence as Unifier
What it is is fixed prior to existence or the object's worldly features [Fine,K]
9. Objects / D. Essence of Objects / 9. Essence and Properties
Essential features of an object have no relation to how things actually are [Fine,K]
9. Objects / F. Identity among Objects / 5. Self-Identity
Self-identity should have two components, its existence, and its neutral identity with itself [Fine,K]
9. Objects / F. Identity among Objects / 6. Identity between Objects
We would understand identity between objects, even if their existence was impossible [Fine,K]
10. Modality / A. Necessity / 8. Transcendental Necessity
Proper necessary truths hold whatever the circumstances; transcendent truths regardless of circumstances [Fine,K]
10. Modality / C. Sources of Modality / 6. Necessity from Essence
It is the nature of Socrates to be a man, so necessarily he is a man [Fine,K]
10. Modality / E. Possible worlds / 2. Nature of Possible Worlds / a. Nature of possible worlds
Possible worlds may be more limited, to how things might actually turn out [Fine,K]
The actual world is a totality of facts, so we also think of possible worlds as totalities [Fine,K]
21. Aesthetics / C. Artistic Issues / 1. Artistic Intentions
When we admire a work, we see ourselves as its creator [Weil]
25. Social Practice / B. Equalities / 1. Grounds of equality
Relationships depend on equality, so unequal treatment kills them [Weil]
27. Natural Reality / D. Time / 2. Passage of Time / c. Tenses and time
It is said that in the A-theory, all existents and objects must be tensed, as well as the sentences [Fine,K]
A-theorists tend to reject the tensed/tenseless distinction [Fine,K]
27. Natural Reality / D. Time / 2. Passage of Time / f. Tenseless (B) series
B-theorists say tensed sentences have an unfilled argument-place for a time [Fine,K]
29. Religion / B. Monotheistic Religion / 5. Bible
The cruelty of the Old Testament put me off Christianity [Weil]
29. Religion / D. Religious Issues / 2. Immortality / a. Immortality
I attach little importance to immortality, which is an undecidable fact, and irrelevant to us [Weil]