Combining Texts

All the ideas for 'Thought and Talk', 'What is Logic?' and 'works'

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20 ideas

2. Reason / D. Definition / 3. Types of Definition
A decent modern definition should always imply a semantics [Hacking]
3. Truth / A. Truth Problems / 1. Truth
A sentence is held true because of a combination of meaning and belief [Davidson]
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]
11. Knowledge Aims / A. Knowledge / 4. Belief / a. Beliefs
Having a belief involves the possibility of being mistaken [Davidson]
11. Knowledge Aims / A. Knowledge / 4. Belief / e. Belief holism
The concept of belief can only derive from relationship to a speech community [Davidson]
18. Thought / A. Modes of Thought / 1. Thought
Thought depends on speech [Davidson]
18. Thought / A. Modes of Thought / 8. Human Thought
A creature doesn't think unless it interprets another's speech [Davidson]
18. Thought / D. Concepts / 5. Concepts and Language / a. Concepts and language
Concepts are only possible in a language community [Davidson]
19. Language / A. Nature of Meaning / 6. Meaning as Use
An understood sentence can be used for almost anything; it isn't language if it has only one use [Davidson]
19. Language / A. Nature of Meaning / 7. Meaning Holism / b. Language holism
The pattern of sentences held true gives sentences their meaning [Davidson]
23. Ethics / F. Existentialism / 6. Authentic Self
Sartre gradually realised that freedom is curtailed by the weight of situation [Sartre, by Daigle]