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All the ideas for 'What is Logic?st1=Ian Hacking', 'Review: Meinong 'Untersuchungen zur..'' and 'fragments/reports'

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20 ideas

1. Philosophy / D. Nature of Philosophy / 6. Hopes for Philosophy
1749 If all laws were abolished, philosophers would still live as they do now [Aristippus elder]
1. Philosophy / F. Analytic Philosophy / 6. Logical Analysis
21546 We can't sharply distinguish variables, domains and values, if symbols frighten us [Russell]
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
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]
13833 '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
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 / 2. Logical Connectives / a. Logical connectives
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]
9. Objects / A. Existence of Objects / 4. Impossible objects
21531 Common sense agrees with Meinong (rather than Russell) that 'Pegasus is a flying horse' is true [Lackey on Russell]
21545 I prefer to deny round squares, and deal with the difficulties by the theory of denoting [Russell]
22. Metaethics / A. Ethics Foundations / 1. Nature of Ethics / h. Against ethics
3558 Only the Cyrenaics reject the idea of a final moral end [Aristippus elder, by Annas]
22. Metaethics / C. The Good / 2. Happiness / d. Routes to happiness
5835 The road of freedom is the surest route to happiness [Aristippus elder, by Xenophon]
23. Ethics / A. Egoism / 3. Cyrenaic School
1751 Pleasure is the good, because we always seek it, it satisfies us, and its opposite is the most avoidable thing [Aristippus elder, by Diog. Laertius]
3018 People who object to extravagant pleasures just love money [Aristippus elder, by Diog. Laertius]
25. Social Practice / D. Justice / 3. Punishment / b. Retribution for crime
1755 Errors result from external influence, and should be corrected, not hated [Aristippus elder, by Diog. Laertius]