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All the ideas for 'What is Logic?st1=Ian Hacking', 'Consistency and realism (with 1972 note)' and 'Sameness and Substance'

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41 ideas

1. Philosophy / F. Analytic Philosophy / 5. Linguistic Analysis
Semantic facts are preferable to transcendental philosophical fiction [Wiggins]
2. Reason / D. Definition / 3. Types of Definition
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
Gentzen's Cut Rule (or transitivity of deduction) is 'If A |- B and B |- C, then A |- C' [Hacking]
Only Cut reduces complexity, so logic is constructive without it, and it can be dispensed with [Hacking]
'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
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
First-order logic is the strongest complete compact theory with Löwenheim-Skolem [Hacking]
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
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
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
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
If it is a logic, the Löwenheim-Skolem theorem holds for it [Hacking]
6. Mathematics / A. Nature of Mathematics / 4. Using Numbers / d. Counting via concepts
Maybe the concept needed under which things coincide must also yield a principle of counting [Wiggins]
The sortal needed for identities may not always be sufficient to support counting [Wiggins]
7. Existence / D. Theories of Reality / 2. Realism
Realist Conceptualists accept that our interests affect our concepts [Wiggins]
Conceptualism says we must use our individuating concepts to grasp reality [Wiggins]
7. Existence / E. Categories / 3. Proposed Categories
Animal classifications: the Emperor's, fabulous, innumerable, like flies, stray dogs, embalmed…. [Wiggins]
9. Objects / A. Existence of Objects / 5. Individuation / a. Individuation
Individuation needs accounts of identity, of change, and of singling out [Wiggins]
Individuation can only be understood by the relation between things and thinkers [Wiggins]
9. Objects / A. Existence of Objects / 5. Individuation / c. Individuation by location
Singling out extends back and forward in time [Wiggins]
9. Objects / A. Existence of Objects / 5. Individuation / e. Individuation by kind
The only singling out is singling out 'as' something [Wiggins]
In Aristotle's sense, saying x falls under f is to say what x is [Wiggins]
Every determinate thing falls under a sortal, which fixes its persistence [Wiggins]
9. Objects / D. Essence of Objects / 5. Essence as Kind
Natural kinds are well suited to be the sortals which fix substances [Wiggins]
9. Objects / D. Essence of Objects / 11. Essence of Artefacts
Artefacts are individuated by some matter having a certain function [Wiggins]
9. Objects / D. Essence of Objects / 13. Nominal Essence
Nominal essences don't fix membership, ignore evolution, and aren't contextual [Wiggins]
9. Objects / E. Objects over Time / 1. Objects over Time
'What is it?' gives the kind, nature, persistence conditions and identity over time of a thing [Wiggins]
9. Objects / E. Objects over Time / 7. Intermittent Objects
A restored church is the same 'church', but not the same 'building' or 'brickwork' [Wiggins]
A thing begins only once; for a clock, it is when its making is first completed [Wiggins]
9. Objects / E. Objects over Time / 9. Ship of Theseus
Priests prefer the working ship; antiquarians prefer the reconstruction [Wiggins]
9. Objects / F. Identity among Objects / 2. Defining Identity
Identity is primitive [Wiggins]
Identity cannot be defined, because definitions are identities [Wiggins]
Leibniz's Law (not transitivity, symmetry, reflexivity) marks what is peculiar to identity [Wiggins]
9. Objects / F. Identity among Objects / 6. Identity between Objects
A is necessarily A, so if B is A, then B is also necessarily A [Wiggins]
9. Objects / F. Identity among Objects / 7. Indiscernible Objects
By the principle of Indiscernibility, a symmetrical object could only be half of itself! [Wiggins]
9. Objects / F. Identity among Objects / 9. Sameness
We want to explain sameness as coincidence of substance, not as anything qualitative [Wiggins]
10. Modality / D. Knowledge of Modality / 4. Conceivable as Possible / a. Conceivable as possible
It is hard or impossible to think of Caesar as not human [Wiggins]
13. Knowledge Criteria / E. Relativism / 5. Language Relativism
Our sortal concepts fix what we find in experience [Wiggins]
18. Thought / D. Concepts / 2. Origin of Concepts / b. Empirical concepts
We conceptualise objects, but they impinge on us [Wiggins]
18. Thought / D. Concepts / 4. Structure of Concepts / f. Theory theory of concepts
A 'conception' of a horse is a full theory of what it is (and not just the 'concept') [Wiggins]
22. Metaethics / A. Ethics Foundations / 1. Nature of Ethics / f. Ethical non-cognitivism
We tolerate inconsistency in ethics but not in other beliefs (which reflect an independent order) [Williams,B, by Foot]