Combining Texts

All the ideas for 'The Origin of the Species', 'What is Logic?' and 'The Case against Closure (and reply)'

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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]
13. Knowledge Criteria / A. Justification Problems / 2. Justification Challenges / c. Knowledge closure
19544 Closure says if you know P, and also know P implies Q, then you must know Q [Dretske]
19545 We needn't regret the implications of our regrets; regretting drinking too much implies the past is real [Dretske]
19547 Reasons for believing P may not transmit to its implication, Q [Dretske]
19546 Knowing by visual perception is not the same as knowing by implication [Dretske]
19548 The only way to preserve our homely truths is to abandon closure [Dretske]
19549 P may imply Q, but evidence for P doesn't imply evidence for Q, so closure fails [Dretske]
19550 We know past events by memory, but we don't know the past is real (an implication) by memory [Dretske]
14. Science / D. Explanation / 3. Best Explanation / a. Best explanation
16861 A false theory could hardly rival the explanatory power of natural selection [Darwin]