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All the ideas for 'What is Logic?st1=Ian Hacking', 'A Free Will' and 'Explanatory Coherence'

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24 ideas

1. Philosophy / C. History of Philosophy / 2. Ancient Philosophy / e. Late classical philosophy
23326 In the third century Stoicism died out, replaced by Platonism, with Aristotelian ethics [Frede,M]
23335 In late antiquity nearly all philosophers were monotheists [Frede,M]
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]
14. Science / D. Explanation / 2. Types of Explanation / c. Explanations by coherence
17066 3: If an analogous pair explain another analogous pair, then they all cohere [Thagard, by Smart]
17064 1: Coherence is a symmetrical relation between two propositions [Thagard, by Smart]
17067 4: For coherence, observation reports have a degree of intrinsic acceptability [Thagard, by Smart]
17068 5: Contradictory propositions incohere [Thagard, by Smart]
17069 6: A proposition's acceptability depends on its coherence with a system [Thagard, by Smart]
17065 2: An explanation must wholly cohere internally, and with the new fact [Thagard, by Smart]
16. Persons / F. Free Will / 2. Sources of Free Will
23337 The Stoics needed free will, to allow human choices in a divinely providential cosmos [Frede,M]
23333 The idea of free will achieved universal acceptance because of Christianity [Frede,M]
23334 For Christians man has free will by creation in God's image (as in Genesis) [Frede,M]
20. Action / B. Preliminaries of Action / 2. Willed Action / a. Will to Act
23336 There is no will for Plato or Aristotle, because actions come directly from perception of what is good [Frede,M]
29. Religion / A. Polytheistic Religion / 4. Dualist Religion
23313 The Gnostic demiurge (creator) is deluded, and doesn't care about us [Frede,M]