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All the ideas for 'What is Logic?st1=Ian Hacking', 'The Common-Sense View of Reality' and 'Logicism and Ontological Commits. of Arithmetic'

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27 ideas

1. Philosophy / E. Nature of Metaphysics / 2. Possibility of Metaphysics
20728 Metaphysics is hopeless with its present epistemology; common-sense realism is needed [Colvin]
2. Reason / D. Definition / 3. Types of Definition
13838 A decent modern definition should always imply a semantics [Hacking]
3. Truth / F. Semantic Truth / 2. Semantic Truth
10017 Truth in a model is more tractable than the general notion of truth [Hodes]
10018 Truth is quite different in interpreted set theory and in the skeleton of its language [Hodes]
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]
10015 Higher-order logic may be unintelligible, but it isn't set theory [Hodes]
5. Theory of Logic / D. Assumptions for Logic / 4. Identity in Logic
10011 Identity is a level one relation with a second-order definition [Hodes]
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 / I. Semantics of Logic / 1. Semantics of Logic
10016 When an 'interpretation' creates a model based on truth, this doesn't include Fregean 'sense' [Hodes]
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]
6. Mathematics / A. Nature of Mathematics / 3. Nature of Numbers / a. Numbers
10027 Mathematics is higher-order modal logic [Hodes]
6. Mathematics / A. Nature of Mathematics / 4. Using Numbers / f. Arithmetic
10026 Arithmetic must allow for the possibility of only a finite total of objects [Hodes]
6. Mathematics / C. Sources of Mathematics / 1. Mathematical Platonism / a. For mathematical platonism
10021 It is claimed that numbers are objects which essentially represent cardinality quantifiers [Hodes]
10022 Numerical terms can't really stand for quantifiers, because that would make them first-level [Hodes]
7. Existence / D. Theories of Reality / 2. Realism
20726 We can only distinguish self from non-self if there is an inflexible external reality [Colvin]
20727 Common-sense realism rests on our interests and practical life [Colvin]
7. Existence / D. Theories of Reality / 4. Anti-realism
20729 Arguments that objects are unknowable or non-existent assume the knower's existence [Colvin]
20730 If objects are doubted because their appearances change, that presupposes one object [Colvin]
20731 The idea that everything is relations is contradictory; relations are part of the concept of things [Colvin]
7. Existence / D. Theories of Reality / 7. Fictionalism
10023 Talk of mirror images is 'encoded fictions' about real facts [Hodes]