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All the ideas for 'What is Logic?st1=Ian Hacking', 'The Varieties of Necessity' and 'Essence and Modality'

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35 ideas

1. Philosophy / F. Analytic Philosophy / 4. Conceptual Analysis
My account shows how the concept works, rather than giving an analysis [Fine,K]
2. Reason / D. Definition / 3. Types of Definition
A decent modern definition should always imply a semantics [Hacking]
2. Reason / D. Definition / 4. Real Definition
Modern philosophy has largely abandoned real definitions, apart from sortals [Fine,K]
2. Reason / D. Definition / 6. Definition by Essence
Defining a term and giving the essence of an object don't just resemble - they are the same [Fine,K]
4. Formal Logic / B. Propositional Logic PL / 2. Tools of Propositional Logic / d. Basic theorems of PL
'Thinning' ('dilution') is the key difference between deduction (which allows it) and induction [Hacking]
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]
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]
7. Existence / C. Structure of Existence / 4. Ontological Dependence
An object is dependent if its essence prevents it from existing without some other object [Fine,K]
9. Objects / D. Essence of Objects / 2. Types of Essence
Essences are either taken as real definitions, or as necessary properties [Fine,K]
9. Objects / D. Essence of Objects / 6. Essence as Unifier
Essentially having a property is naturally expressed as 'the property it must have to be what it is' [Fine,K]
9. Objects / D. Essence of Objects / 7. Essence and Necessity / a. Essence as necessary properties
Simple modal essentialism refers to necessary properties of an object [Fine,K]
Essentialist claims can be formulated more clearly with quantified modal logic [Fine,K]
9. Objects / D. Essence of Objects / 7. Essence and Necessity / b. Essence not necessities
Metaphysical necessity is a special case of essence, not vice versa [Fine,K]
Essence as necessary properties produces a profusion of essential properties [Fine,K, by Lowe]
The nature of singleton Socrates has him as a member, but not vice versa [Fine,K]
It is not part of the essence of Socrates that a huge array of necessary truths should hold [Fine,K]
9. Objects / D. Essence of Objects / 8. Essence as Explanatory
An essential property of something must be bound up with what it is to be that thing [Fine,K, by Rami]
9. Objects / D. Essence of Objects / 9. Essence and Properties
Essential properties are part of an object's 'definition' [Fine,K, by Rami]
9. Objects / E. Objects over Time / 12. Origin as Essential
If Socrates lacks necessary existence, then his nature cannot require his parents' existence [Fine,K]
10. Modality / C. Sources of Modality / 1. Sources of Necessity
The subject of a proposition need not be the source of its necessity [Fine,K]
Each area of enquiry, and its source, has its own distinctive type of necessity [Fine,K]
10. Modality / C. Sources of Modality / 4. Necessity from Concepts
Conceptual necessities rest on the nature of all concepts [Fine,K]
10. Modality / C. Sources of Modality / 6. Necessity from Essence
Socrates is necessarily distinct from the Eiffel Tower, but that is not part of his essence [Fine,K]
Metaphysical necessities are true in virtue of the nature of all objects [Fine,K]
13. Knowledge Criteria / C. External Justification / 7. Testimony
Unsupported testimony may still be believable [Fine,K]
19. Language / E. Analyticity / 2. Analytic Truths
Analytic truth may only be true in virtue of the meanings of certain terms [Fine,K]
The meaning of 'bachelor' is irrelevant to the meaning of 'unmarried man' [Fine,K]
26. Natural Theory / D. Laws of Nature / 8. Scientific Essentialism / a. Scientific essentialism
Causation is easier to disrupt than logic, so metaphysics is part of nature, not vice versa [Fine,K]