Combining Texts

All the ideas for 'How the Laws of Physics Lie', 'Set Theory and Its Philosophy' and 'Model Theory'

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39 ideas

2. Reason / D. Definition / 7. Contextual Definition
The idea that groups of concepts could be 'implicitly defined' was abandoned [Hodges,W]
4. Formal Logic / F. Set Theory ST / 1. Set Theory
Set theory's three roles: taming the infinite, subject-matter of mathematics, and modes of reasoning [Potter]
4. Formal Logic / F. Set Theory ST / 3. Types of Set / b. Empty (Null) Set
Usually the only reason given for accepting the empty set is convenience [Potter]
4. Formal Logic / F. Set Theory ST / 4. Axioms for Sets / f. Axiom of Infinity V
Infinity: There is at least one limit level [Potter]
4. Formal Logic / F. Set Theory ST / 5. Conceptions of Set / e. Iterative sets
Nowadays we derive our conception of collections from the dependence between them [Potter]
4. Formal Logic / F. Set Theory ST / 5. Conceptions of Set / f. Limitation of Size
The 'limitation of size' principles say whether properties collectivise depends on the number of objects [Potter]
4. Formal Logic / G. Formal Mereology / 1. Mereology
Mereology elides the distinction between the cards in a pack and the suits [Potter]
5. Theory of Logic / A. Overview of Logic / 5. First-Order Logic
Since first-order languages are complete, |= and |- have the same meaning [Hodges,W]
5. Theory of Logic / A. Overview of Logic / 7. Second-Order Logic
We can formalize second-order formation rules, but not inference rules [Potter]
5. Theory of Logic / B. Logical Consequence / 4. Semantic Consequence |=
|= in model-theory means 'logical consequence' - it holds in all models [Hodges,W]
5. Theory of Logic / H. Proof Systems / 3. Proof from Assumptions
Supposing axioms (rather than accepting them) give truths, but they are conditional [Potter]
5. Theory of Logic / I. Semantics of Logic / 4. Satisfaction
|= should be read as 'is a model for' or 'satisfies' [Hodges,W]
5. Theory of Logic / J. Model Theory in Logic / 1. Logical Models
Model theory studies formal or natural language-interpretation using set-theory [Hodges,W]
A 'structure' is an interpretation specifying objects and classes of quantification [Hodges,W]
Models in model theory are structures, not sets of descriptions [Hodges,W]
6. Mathematics / A. Nature of Mathematics / 4. Using Numbers / c. Counting procedure
If set theory didn't found mathematics, it is still needed to count infinite sets [Potter]
6. Mathematics / A. Nature of Mathematics / 5. The Infinite / i. Cardinal infinity
First-order logic can't discriminate between one infinite cardinal and another [Hodges,W]
6. Mathematics / B. Foundations for Mathematics / 4. Axioms for Number / d. Peano arithmetic
It is remarkable that all natural number arithmetic derives from just the Peano Axioms [Potter]
7. Existence / E. Categories / 4. Category Realism
Causality indicates which properties are real [Cartwright,N]
8. Modes of Existence / A. Relations / 4. Formal Relations / a. Types of relation
A relation is a set consisting entirely of ordered pairs [Potter]
9. Objects / B. Unity of Objects / 2. Substance / b. Need for substance
If dependence is well-founded, with no infinite backward chains, this implies substances [Potter]
9. Objects / C. Structure of Objects / 8. Parts of Objects / b. Sums of parts
Collections have fixed members, but fusions can be carved in innumerable ways [Potter]
10. Modality / A. Necessity / 1. Types of Modality
Priority is a modality, arising from collections and members [Potter]
14. Science / D. Explanation / 2. Types of Explanation / a. Types of explanation
Two main types of explanation are by causes, or by citing a theoretical framework [Cartwright,N]
14. Science / D. Explanation / 2. Types of Explanation / c. Explanations by coherence
An explanation is a model that fits a theory and predicts the phenomenological laws [Cartwright,N]
14. Science / D. Explanation / 2. Types of Explanation / e. Lawlike explanations
Laws get the facts wrong, and explanation rests on improvements and qualifications of laws [Cartwright,N]
Laws apply to separate domains, but real explanations apply to intersecting domains [Cartwright,N]
Covering-law explanation lets us explain storms by falling barometers [Cartwright,N]
I disagree with the covering-law view that there is a law to cover every single case [Cartwright,N]
You can't explain one quail's behaviour by just saying that all quails do it [Cartwright,N]
The covering law view assumes that each phenomenon has a 'right' explanation [Cartwright,N]
14. Science / D. Explanation / 3. Best Explanation / c. Against best explanation
In science, best explanations have regularly turned out to be false [Cartwright,N]
26. Natural Theory / C. Causation / 8. Particular Causation / e. Probabilistic causation
A cause won't increase the effect frequency if other causes keep interfering [Cartwright,N]
26. Natural Theory / D. Laws of Nature / 2. Types of Laws
There are fundamental explanatory laws (false!), and phenomenological laws (regularities) [Cartwright,N, by Bird]
Laws of appearances are 'phenomenological'; laws of reality are 'theoretical' [Cartwright,N]
26. Natural Theory / D. Laws of Nature / 4. Regularities / b. Best system theory
Good organisation may not be true, and the truth may not organise very much [Cartwright,N]
26. Natural Theory / D. Laws of Nature / 11. Against Laws of Nature
To get from facts to equations, we need a prepared descriptions suited to mathematics [Cartwright,N]
Simple laws have quite different outcomes when they act in combinations [Cartwright,N]
There are few laws for when one theory meets another [Cartwright,N]