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All the ideas for 'What is Logic?st1=Ian Hacking', 'On Sensations (frags)' and 'Notebooks 1914-1916'

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21 ideas

1. Philosophy / F. Analytic Philosophy / 5. Linguistic Analysis
18274 Analysis complicates a statement, but only as far as the complexity of its meaning [Wittgenstein]
2. Reason / D. Definition / 3. Types of Definition
13838 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
13833 'Thinning' ('dilution') is the key difference between deduction (which allows it) and induction [Hacking]
13834 Gentzen's Cut Rule (or transitivity of deduction) is 'If A |- B and B |- C, then A |- C' [Hacking]
13835 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 / 1. Overview of Logic
16908 We can dispense with self-evidence, if language itself prevents logical mistakes [Jeshion on Wittgenstein]
5. Theory of Logic / A. Overview of Logic / 4. Pure Logic
13845 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
13840 First-order logic is the strongest complete compact theory with Löwenheim-Skolem [Hacking]
13844 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
13842 Second-order completeness seems to need intensional entities and possible worlds [Hacking]
5. Theory of Logic / E. Structures of Logic / 1. Logical Form
18276 A statement's logical form derives entirely from its constituents [Wittgenstein]
5. Theory of Logic / E. Structures of Logic / 2. Logical Connectives / a. Logical connectives
6563 'And' and 'not' are non-referring terms, which do not represent anything [Wittgenstein, by Fogelin]
13837 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
13839 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
13843 If it is a logic, the Löwenheim-Skolem theorem holds for it [Hacking]
7. Existence / C. Structure of Existence / 6. Fundamentals / d. Logical atoms
23472 The sense of propositions relies on the world's basic logical structure [Wittgenstein]
12. Knowledge Sources / A. A Priori Knowledge / 5. A Priori Synthetic
23500 My main problem is the order of the world, and whether it is knowable a priori [Wittgenstein]
13. Knowledge Criteria / E. Relativism / 3. Subjectivism
2975 That honey is sweet I do not affirm, but I agree that it appears so [Timon]
16. Persons / B. Nature of the Self / 4. Presupposition of Self
22323 The philosophical I is the metaphysical subject, the limit - not a part of the world [Wittgenstein]
19. Language / A. Nature of Meaning / 2. Meaning as Mental
23481 Propositions assemble a world experimentally, like the model of a road accident [Wittgenstein]
25. Social Practice / F. Life Issues / 4. Suicide
4678 Absolute prohibitions are the essence of ethics, and suicide is the most obvious example [Wittgenstein]