Combining Texts

All the ideas for 'What is Logic?st1=Ian Hacking', 'Scientific Thought' and 'Elucidation of some points in E.Schrder'

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17 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]
4. Formal Logic / F. Set Theory ST / 3. Types of Set / b. Empty (Null) Set
14238 A class is an aggregate of objects; if you destroy them, you destroy the class; there is no empty class [Frege]
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 / E. Objects over Time / 4. Four-Dimensionalism
14759 A thing is simply a long event, linked by qualities, and spatio-temporal unity [Broad]
11842 If short-lived happenings like car crashes are 'events', why not long-lived events like Dover Cliffs? [Broad]
27. Natural Reality / D. Time / 1. Nature of Time / g. Growing block
8160 The present and past exist, but the future does not [Broad, by Dummett]
14609 We could say present and past exist, but not future, so that each event adds to the total history [Broad]
27. Natural Reality / D. Time / 2. Passage of Time / d. Time series
22933 We imagine the present as a spotlight, moving across events from past to future [Broad]