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All the ideas for 'What is Logic?st1=Ian Hacking', 'MacIntyre versus the Enlightenment' and 'Gravity and Grace (9 extracts)'

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23 ideas

2. Reason / D. Definition / 3. Types of Definition
13838 A decent modern definition should always imply a semantics [Hacking]
3. Truth / A. Truth Problems / 3. Value of Truth
23825 We seek truth only because it is good [Weil]
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 / 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]
13. Knowledge Criteria / E. Relativism / 4. Cultural relativism
1490 You would have to be very morally lazy to ignore criticisms of your own culture [Nagel]
22. Metaethics / A. Ethics Foundations / 2. Source of Ethics / a. Idealistic ethics
23826 Beauty, goodness and truth are only achieved by applying full attention [Weil]
22. Metaethics / C. The Good / 1. Goodness / a. Form of the Good
23833 The good is a nothingness, and yet real [Weil]
23808 There are two goods - the absolute good we want, and the reachable opposite of evil [Weil]
24. Political Theory / C. Ruling a State / 1. Social Power
23831 The essence of power is illusory prestige [Weil]
24. Political Theory / D. Ideologies / 1. Ideology
23830 A group is only dangerous if it endorses an abstract entity [Weil]
24. Political Theory / D. Ideologies / 2. Anarchism
23809 Our only social duty is to try to limit evil [Weil]
24. Political Theory / D. Ideologies / 9. Communism
23807 The collective is the one and only object of false idolatry [Weil]
24. Political Theory / D. Ideologies / 14. Nationalism
23810 Charity is the only love, and you can feel that for a country (a place with traditions), but not a nation [Weil]
25. Social Practice / A. Freedoms / 1. Slavery
23811 If effort is from necessity rather than for a good, it is slavery [Weil]
29. Religion / D. Religious Issues / 2. Immortality / b. Soul
23765 The soul is the intrinsic value of a human [Weil]