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All the ideas for 'What is Logic?st1=Ian Hacking', 'Introduction to the Philosophy of History' and 'An Introduction to Modal Logic'

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23 ideas

1. Philosophy / C. History of Philosophy / 4. Later European Philosophy / d. Nineteenth century philosophy
20109 Hegel inserted society and history between the God-world, man-nature, man-being binary pairs [Hegel, by Safranski]
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 / b. Terminology of PL
9540 A 'value-assignment' (V) is when to each variable in the set V assigns either the value 1 or the value 0 [Hughes/Cresswell]
4. Formal Logic / B. Propositional Logic PL / 2. Tools of Propositional Logic / d. Basic theorems of PL
9541 The Law of Transposition says (P→Q) → (¬Q→¬P) [Hughes/Cresswell]
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]
4. Formal Logic / B. Propositional Logic PL / 4. Soundness of PL
9543 The rules preserve validity from the axioms, so no thesis negates any other thesis [Hughes/Cresswell]
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]
5. Theory of Logic / K. Features of Logics / 4. Completeness
9544 A system is 'weakly' complete if all wffs are derivable, and 'strongly' if theses are maximised [Hughes/Cresswell]
22. Metaethics / C. The Good / 2. Happiness / a. Nature of happiness
23274 World history has no room for happiness [Hegel]
24. Political Theory / A. Basis of a State / 1. A People / b. The natural life
23275 The state of nature is one of untamed brutality [Hegel]
24. Political Theory / A. Basis of a State / 1. A People / c. A unified people
23276 The soul of the people is an organisation of its members which produces an essential unity [Hegel]
24. Political Theory / D. Ideologies / 6. Liberalism / g. Liberalism critique
23272 The human race matters, and individuals have little importance [Hegel]
24. Political Theory / D. Ideologies / 14. Nationalism
23273 In a good state the goal of the citizens and of the whole state are united [Hegel]
25. Social Practice / A. Freedoms / 5. Freedom of lifestyle
23271 The goal of the world is Spirit's consciousness and enactment of freedom [Hegel]
25. Social Practice / E. Policies / 5. Education / d. Study of history
23270 We should all agree that there is reason in history [Hegel]