Combining Texts

All the ideas for 'What is Logic?st1=Ian Hacking', 'De primae philosophiae emendatione' and 'The Structure of Appearance'

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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
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]
4. Formal Logic / F. Set Theory ST / 5. Conceptions of Set / a. Sets as existing
15510 Classes are a host of ethereal, platonic, pseudo entities [Goodman]
4. Formal Logic / F. Set Theory ST / 8. Critique of Set Theory
9920 Two objects can apparently make up quite distinct arrangements in sets [Goodman, by Burgess/Rosen]
4. Formal Logic / G. Formal Mereology / 1. Mereology
10657 The counties of Utah, and the state, and its acres, are in no way different [Goodman]
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]
8. Modes of Existence / E. Nominalism / 2. Resemblance Nominalism
7956 If all and only red things were round things, we would need to specify the 'respect' of the resemblance [Goodman, by Macdonald,C]
7957 Without respects of resemblance, we would collect blue book, blue pen, red pen, red clock together [Goodman, by Macdonald,C]
8. Modes of Existence / E. Nominalism / 3. Predicate Nominalism
7952 If we apply the same word to different things, it is only because we are willing to do so [Goodman, by Macdonald,C]
9. Objects / B. Unity of Objects / 2. Substance / a. Substance
12716 The concept of forces or powers best reveals the true concept of substance [Leibniz]