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All the ideas for 'What is Logic?st1=Ian Hacking', 'How to Define Theoretical Terms' and 'Properties'

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34 ideas

2. Reason / B. Laws of Thought / 6. Ockham's Razor
What matters is not how many entities we postulate, but how many kinds of entities [Armstrong, by Mellor/Oliver]
2. Reason / D. Definition / 2. Aims of Definition
Defining terms either enables elimination, or shows that they don't require elimination [Lewis]
2. Reason / D. Definition / 3. Types of Definition
A decent modern definition should always imply a semantics [Hacking]
4. Formal Logic / B. Propositional Logic PL / 2. Tools of Propositional Logic / d. Basic theorems of PL
Gentzen's Cut Rule (or transitivity of deduction) is 'If A |- B and B |- C, then A |- C' [Hacking]
Only Cut reduces complexity, so logic is constructive without it, and it can be dispensed with [Hacking]
'Thinning' ('dilution') is the key difference between deduction (which allows it) and induction [Hacking]
5. Theory of Logic / A. Overview of Logic / 4. Pure Logic
The various logics are abstractions made from terms like 'if...then' in English [Hacking]
5. Theory of Logic / A. Overview of Logic / 5. First-Order Logic
First-order logic is the strongest complete compact theory with Löwenheim-Skolem [Hacking]
A limitation of first-order logic is that it cannot handle branching quantifiers [Hacking]
5. Theory of Logic / A. Overview of Logic / 7. Second-Order Logic
Second-order completeness seems to need intensional entities and possible worlds [Hacking]
5. Theory of Logic / E. Structures of Logic / 2. Logical Connectives / a. Logical connectives
With a pure notion of truth and consequence, the meanings of connectives are fixed syntactically [Hacking]
5. Theory of Logic / E. Structures of Logic / 4. Variables in Logic
Perhaps variables could be dispensed with, by arrows joining places in the scope of quantifiers [Hacking]
5. Theory of Logic / J. Model Theory in Logic / 3. Löwenheim-Skolem Theorems
If it is a logic, the Löwenheim-Skolem theorem holds for it [Hacking]
8. Modes of Existence / B. Properties / 2. Need for Properties
Without properties we would be unable to express the laws of nature [Armstrong]
8. Modes of Existence / B. Properties / 10. Properties as Predicates
Whether we apply 'cold' or 'hot' to an object is quite separate from its change of temperature [Armstrong]
To the claim that every predicate has a property, start by eliminating failure of application of predicate [Armstrong]
8. Modes of Existence / B. Properties / 13. Tropes / a. Nature of tropes
Tropes fall into classes, because exact similarity is symmetrical and transitive [Armstrong]
8. Modes of Existence / B. Properties / 13. Tropes / b. Critique of tropes
Trope theory needs extra commitments, to symmetry and non-transitivity, unless resemblance is exact [Armstrong]
8. Modes of Existence / D. Universals / 2. Need for Universals
Universals are required to give a satisfactory account of the laws of nature [Armstrong]
8. Modes of Existence / E. Nominalism / 1. Nominalism / c. Nominalism about abstracta
Deniers of properties and relations rely on either predicates or on classes [Armstrong]
8. Modes of Existence / E. Nominalism / 2. Resemblance Nominalism
Resemblances must be in certain 'respects', and they seem awfully like properties [Armstrong]
8. Modes of Existence / E. Nominalism / 3. Predicate Nominalism
Change of temperature in objects is quite independent of the predicates 'hot' and 'cold' [Armstrong]
We want to know what constituents of objects are grounds for the application of predicates [Armstrong]
8. Modes of Existence / E. Nominalism / 5. Class Nominalism
In most sets there is no property common to all the members [Armstrong]
9. Objects / D. Essence of Objects / 15. Against Essentialism
Essences might support Resemblance Nominalism, but they are too coarse and ill-defined [Armstrong]
10. Modality / E. Possible worlds / 3. Transworld Objects / b. Rigid designation
A logically determinate name names the same thing in every possible world [Lewis]
14. Science / B. Scientific Theories / 8. Ramsey Sentences
The Ramsey sentence of a theory says that it has at least one realisation [Lewis]
A Ramsey sentence just asserts that a theory can be realised, without saying by what [Lewis]
There is a method for defining new scientific terms just using the terms we already understand [Lewis]
It is better to have one realisation of a theory than many - but it may not always be possible [Lewis]
19. Language / C. Assigning Meanings / 3. Predicates
Predicates need ontological correlates to ensure that they apply [Armstrong]
There must be some explanation of why certain predicates are applicable to certain objects [Armstrong]
26. Natural Theory / D. Laws of Nature / 4. Regularities / a. Regularity theory
The introduction of sparse properties avoids the regularity theory's problem with 'grue' [Armstrong]
Regularities theories are poor on causal connections, counterfactuals and probability [Armstrong]