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All the ideas for 'What is Logic?st1=Ian Hacking', 'The Problem of the Essential Indexical' and 'Identity'

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18 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
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 / F. Identity among Objects / 1. Concept of Identity
8970 Our notion of identical sets involves identical members, which needs absolute identity [Hawthorne]
11. Knowledge Aims / A. Knowledge / 4. Belief / b. Elements of beliefs
12149 Indexicals are a problem for beliefs being just subject-proposition relations [Perry]
19. Language / C. Assigning Meanings / 9. Indexical Semantics
12151 If we replace 'I' in sentences about me, they are different beliefs and explanations of behaviour [Perry]
18412 Indexicals individuate certain belief states, helping in explanation and prediction [Perry]
19. Language / D. Propositions / 6. Propositions Critique
12150 Indexicals reveal big problems with the traditional idea of a proposition [Perry]
27. Natural Reality / D. Time / 2. Passage of Time / c. Tenses and time
15203 Tense is essential for thought and action [Perry, by Le Poidevin]
15204 Actual tensed sentences cannot be tenseless, because they can cite their own context [Perry, by Le Poidevin]