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All the ideas for 'What is Logic?st1=Ian Hacking', 'Essence and Potentiality' and 'On the Frame of Reference'

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20 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 / G. Quantification / 4. Substitutional Quantification
10009 Substitutional quantification is just a variant of Tarski's account [Wallace, by Baldwin]
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]
8. Modes of Existence / C. Powers and Dispositions / 4. Powers as Essence
17954 Essence is a thing's necessities, but what about its possibilities (which may not be realised)? [Vetter]
9. Objects / D. Essence of Objects / 4. Essence as Definition
17953 Real definition fits abstracta, but not individual concrete objects like Socrates [Vetter]
9. Objects / D. Essence of Objects / 7. Essence and Necessity / a. Essence as necessary properties
17952 Modal accounts make essence less mysterious, by basing them on the clearer necessity [Vetter]
10. Modality / A. Necessity / 5. Metaphysical Necessity
17959 Metaphysical necessity is even more deeply empirical than Kripke has argued [Vetter]
10. Modality / B. Possibility / 1. Possibility
17955 Possible worlds allow us to talk about degrees of possibility [Vetter]
17957 Maybe possibility is constituted by potentiality [Vetter]
10. Modality / D. Knowledge of Modality / 4. Conceivable as Possible / c. Possible but inconceivable
17958 The apparently metaphysically possible may only be epistemically possible [Vetter]
10. Modality / E. Possible worlds / 1. Possible Worlds / a. Possible worlds
17956 Closeness of worlds should be determined by the intrinsic nature of relevant objects [Vetter]