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All the ideas for 'What is Logic?st1=Ian Hacking', 'Ruling Passions' and 'De Ente et Essentia (Being and Essence)'

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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]
2. Reason / D. Definition / 5. Genus and Differentia
13070 If definitions must be general, and general terms can't individuate, then Socrates can't be defined [Aquinas, by Cover/O'Leary-Hawthorne]
11197 The definitions expressing identity are used to sort things [Aquinas]
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]
7. Existence / A. Nature of Existence / 3. Being / e. Being and nothing
11195 If affirmative propositions express being, we affirm about what is absent [Aquinas]
8. Modes of Existence / B. Properties / 8. Properties as Modes
11201 Properties have an incomplete essence, with definitions referring to their subject [Aquinas]
8. Modes of Existence / D. Universals / 6. Platonic Forms / d. Forms critiques
11205 If the form of 'human' contains 'many', Socrates isn't human; if it contains 'one', Socrates is Plato [Aquinas]
9. Objects / A. Existence of Objects / 5. Individuation / a. Individuation
13090 The principle of diversity for corporeal substances is their matter [Aquinas, by Cover/O'Leary-Hawthorne]
9. Objects / D. Essence of Objects / 1. Essences of Objects
11202 It is by having essence that things exist [Aquinas]
9. Objects / D. Essence of Objects / 2. Types of Essence
11203 Specific individual essence is defined by material, and generic essence is defined by form [Aquinas]
9. Objects / D. Essence of Objects / 4. Essence as Definition
11200 The definition of a physical object must include the material as well as the form [Aquinas]
9. Objects / D. Essence of Objects / 5. Essence as Kind
11196 Essence is something in common between the natures which sort things into categories [Aquinas]
9. Objects / D. Essence of Objects / 6. Essence as Unifier
11208 A simple substance is its own essence [Aquinas]
14. Science / D. Explanation / 2. Types of Explanation / k. Explanations by essence
11198 Definition of essence makes things understandable [Aquinas]
19. Language / C. Assigning Meanings / 3. Predicates
11206 The mind constructs complete attributions, based on the unified elements of the real world [Aquinas]
20. Action / B. Preliminaries of Action / 2. Willed Action / d. Weakness of will
23996 Akrasia is intelligible in hindsight, when we revisit our previous emotions [Blackburn]
26. Natural Theory / C. Causation / 5. Direction of causation
11207 A cause can exist without its effect, but the effect cannot exist without its cause [Aquinas]