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All the ideas for 'What is Logic?st1=Ian Hacking', 'Substance' and '26: Oracles in Decline'

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26 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 / 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 / A. Relations / 4. Formal Relations / c. Ancestral relation
12056 An ancestral relation is either direct or transitively indirect [Wiggins]
8. Modes of Existence / C. Powers and Dispositions / 4. Powers as Essence
12050 Substances contain a source of change or principle of activity [Wiggins]
9. Objects / A. Existence of Objects / 5. Individuation / e. Individuation by kind
12055 Sortal predications are answers to the question 'what is x?' [Wiggins]
12059 A river may change constantly, but not in respect of being a river [Wiggins]
12052 We never single out just 'this', but always 'this something-or-other' [Wiggins]
12063 Sortal classification becomes science, with cross reference clarifying individuals [Wiggins]
12051 If the kinds are divided realistically, they fall into substances [Wiggins]
12053 'Human being' is a better answer to 'what is it?' than 'poet', as the latter comes in degrees [Wiggins]
12054 Secondary substances correctly divide primary substances by activity-principles and relations [Wiggins]
9. Objects / B. Unity of Objects / 2. Substance / d. Substance defined
12047 We refer to persisting substances, in perception and in thought, and they aid understanding [Wiggins]
9. Objects / C. Structure of Objects / 3. Matter of an Object
12057 Matter underlies things, composes things, and brings them to be [Wiggins]
11. Knowledge Aims / C. Knowing Reality / 3. Idealism / a. Idealism
5958 The sun is always bright; it doesn't become bright when it emerges [Plutarch]
14. Science / D. Explanation / 2. Types of Explanation / k. Explanations by essence
12064 The category of substance is more important for epistemology than for ontology [Wiggins]
12049 Naming the secondary substance provides a mass of general information [Wiggins]
15. Nature of Minds / C. Capacities of Minds / 4. Objectification
12065 Seeing a group of soldiers as an army is irresistible, in ontology and explanation [Wiggins]