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All the ideas for 'What is Logic?st1=Ian Hacking', 'Emotivism' and 'Reference and Contingency'

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19 ideas

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 / 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]
10. Modality / B. Possibility / 5. Contingency
14895 'Superficial' contingency: false in some world; 'Deep' contingency: no obvious verification [Evans, by Macià/Garcia-Carpentiro]
10. Modality / E. Possible worlds / 3. Transworld Objects / b. Rigid designation
11881 Rigid designators can be meaningful even if empty [Evans, by Mackie,P]
22. Metaethics / A. Ethics Foundations / 2. Source of Ethics / h. Expressivism
2848 Two people might agree in their emotional moral attitude while disagreeing in their judgement [Brink]
2851 Emotivists find it hard to analyse assertions of moral principles, rather than actual judgements [Brink]
2853 Emotivists claim to explain moral motivation by basing morality on non-cognitive attitudes [Brink]
2852 Emotivists tend to favour a redundancy theory of truth, making moral judgement meaningless [Brink]
2849 Emotivism implies relativism about moral meanings, but critics say disagreements are about moral reference [Brink]
2850 How can emotivists explain someone who recognises morality but is indifferent to it? [Brink]