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All the ideas for 'What is Logic?st1=Ian Hacking', 'Counterparts and Identity' and 'Philosophy and Scientific Image of Man'

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18 ideas

1. Philosophy / D. Nature of Philosophy / 5. Aims of Philosophy / c. Philosophy as generalisation
21829 Philosophy aims to understand how things (broadly understood) hang together (broadly understood) [Sellars]
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 / D. Modal Logic ML / 7. Barcan Formula
18823 To say there could have been people who don't exist, but deny those possible things, rejects Barcan [Stalnaker, by Rumfitt]
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 / C. Structure of Existence / 2. Reduction
6550 Reduction requires that an object's properties consist of its constituents' properties and relations [Sellars]
10. Modality / E. Possible worlds / 3. Transworld Objects / c. Counterparts
16409 Unlike Lewis, I defend an actualist version of counterpart theory [Stalnaker]
16411 If possible worlds really differ, I can't be in more than one at a time [Stalnaker]
16412 If counterparts exist strictly in one world only, this seems to be extreme invariant essentialism [Stalnaker]
19. Language / C. Assigning Meanings / 8. Possible Worlds Semantics
16410 Extensional semantics has individuals and sets; modal semantics has intensions, functions of world to extension [Stalnaker]