Combining Texts

All the ideas for 'Universal Prescriptivism', 'Set Theory and its Logic' and 'What is Logic?'

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22 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]
4. Formal Logic / F. Set Theory ST / 4. Axioms for Sets / p. Axiom of Reducibility
21717 Reducibility undermines type ramification, and is committed to the existence of functions [Quine, by Linsky,B]
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]
22. Metaethics / A. Ethics Foundations / 2. Source of Ethics / c. Ethical intuitionism
2705 How can intuitionists distinguish universal convictions from local cultural ones? [Hare]
2712 You can't use intuitions to decide which intuitions you should cultivate [Hare]
22. Metaethics / A. Ethics Foundations / 2. Source of Ethics / h. Expressivism
2706 Emotivists mistakenly think all disagreements are about facts, and so there are no moral reasons [Hare]
22. Metaethics / A. Ethics Foundations / 2. Source of Ethics / i. Prescriptivism
2709 Prescriptivism sees 'ought' statements as imperatives which are universalisable [Hare]
2704 If morality is just a natural or intuitive description, that leads to relativism [Hare]
2703 Descriptivism say ethical meaning is just truth-conditions; prescriptivism adds an evaluation [Hare]
2707 If there can be contradictory prescriptions, then reasoning must be involved [Hare]
2708 An 'ought' statement implies universal application [Hare]
2711 Prescriptivism implies a commitment, but descriptivism doesn't [Hare]
23. Ethics / D. Deontological Ethics / 3. Universalisability
2710 Moral judgements must invoke some sort of principle [Hare]