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All the ideas for 'What is Logic?st1=Ian Hacking', 'Vagueness, Truth and Logic' and 'works'

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29 ideas

1. Philosophy / F. Analytic Philosophy / 6. Logical Analysis
Study vagueness first by its logic, then by its truth-conditions, and then its metaphysics [Fine,K]
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
'Thinning' ('dilution') is the key difference between deduction (which allows it) and induction [Hacking]
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]
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 / D. Assumptions for Logic / 2. Excluded Middle
Excluded Middle, and classical logic, may fail for vague predicates [Fine,K]
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 / I. Semantics of Logic / 3. Logical Truth
Logic holding between indefinite sentences is the core of all language [Fine,K]
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]
6. Mathematics / A. Nature of Mathematics / 3. Nature of Numbers / g. Real numbers
Descartes showed a one-one order-preserving match between points on a line and the real numbers [Descartes, by Hart,WD]
7. Existence / D. Theories of Reality / 10. Vagueness / d. Vagueness as linguistic
Vagueness is semantic, a deficiency of meaning [Fine,K]
7. Existence / D. Theories of Reality / 10. Vagueness / e. Higher-order vagueness
A thing might be vaguely vague, giving us higher-order vagueness [Fine,K]
7. Existence / D. Theories of Reality / 10. Vagueness / f. Supervaluation for vagueness
A vague sentence is only true for all ways of making it completely precise [Fine,K]
Logical connectives cease to be truth-functional if vagueness is treated with three values [Fine,K]
Meaning is both actual (determining instances) and potential (possibility of greater precision) [Fine,K]
With the super-truth approach, the classical connectives continue to work [Fine,K]
Borderline cases must be under our control, as capable of greater precision [Fine,K]
9. Objects / B. Unity of Objects / 2. Substance / e. Substance critique
Descartes thinks distinguishing substances from aggregates is pointless [Descartes, by Pasnau]
9. Objects / B. Unity of Objects / 3. Unity Problems / e. Vague objects
Vagueness can be in predicates, names or quantifiers [Fine,K]
12. Knowledge Sources / B. Perception / 3. Representation
Descartes said images can refer to objects without resembling them (as words do) [Descartes, by Tuck]
16. Persons / F. Free Will / 4. For Free Will
We have inner awareness of our freedom [Descartes]
17. Mind and Body / A. Mind-Body Dualism / 2. Interactionism
Descartes discussed the interaction problem, and compared it with gravity [Descartes, by Lycan]
26. Natural Theory / A. Speculations on Nature / 1. Nature
Nature is devoid of thought [Descartes, by Meillassoux]
26. Natural Theory / A. Speculations on Nature / 7. Later Matter Theories / c. Matter as extension
Matter can't just be Descartes's geometry, because a filler of the spaces is needed [Robinson,H on Descartes]