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

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36 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]
3. Truth / A. Truth Problems / 5. Truth Bearers
A statement S is 'partly true' if it has some wholly true parts [Yablo]
4. Formal Logic / A. Syllogistic Logic / 2. Syllogistic Logic
An 'enthymeme' is an argument with an indispensable unstated assumption [Yablo]
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]
4. Formal Logic / G. Formal Mereology / 3. Axioms of Mereology
y is only a proper part of x if there is a z which 'makes up the difference' between them [Yablo]
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 / F. Referring in Logic / 1. Naming / e. Empty names
'Pegasus doesn't exist' is false without Pegasus, yet the absence of Pegasus is its truthmaker [Yablo]
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 / C. Sources of Mathematics / 3. Mathematical Nominalism
A nominalist can assert statements about mathematical objects, as being partly true [Yablo]
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 / 3. Unity Problems / e. Vague objects
Vagueness can be in predicates, names or quantifiers [Fine,K]
9. Objects / C. Structure of Objects / 8. Parts of Objects / a. Parts of objects
Parthood lacks the restriction of kind which most relations have [Yablo]
13. Knowledge Criteria / A. Justification Problems / 2. Justification Challenges / b. Gettier problem
Gettier says you don't know if you are confused about how it is true [Yablo]
14. Science / B. Scientific Theories / 2. Aim of Science
A theory need not be true to be good; it should just be true about its physical aspects [Yablo]
14. Science / C. Induction / 5. Paradoxes of Induction / b. Raven paradox
If sentences point to different evidence, they must have different subject-matter [Yablo]
Most people say nonblack nonravens do confirm 'all ravens are black', but only a tiny bit [Yablo]
19. Language / A. Nature of Meaning / 4. Meaning as Truth-Conditions
Sentence-meaning is the truth-conditions - plus factors responsible for them [Yablo]
19. Language / C. Assigning Meanings / 4. Compositionality
The content of an assertion can be quite different from compositional content [Yablo]
19. Language / C. Assigning Meanings / 6. Truth-Conditions Semantics
Truth-conditions as subject-matter has problems of relevance, short cut, and reversal [Yablo]
19. Language / F. Communication / 3. Denial
Not-A is too strong to just erase an improper assertion, because it actually reverses A [Yablo]