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All the ideas for 'What is Logic?st1=Ian Hacking', 'MacIntyre versus the Enlightenment' and 'On Eternal and Immutable Morality'

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20 ideas

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
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]
13833 '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
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]
12. Knowledge Sources / A. A Priori Knowledge / 3. Innate Knowledge / c. Tabula rasa
6230 If the soul were a tabula rasa, with no innate ideas, there could be no moral goodness or justice [Cudworth]
12. Knowledge Sources / D. Empiricism / 5. Empiricism Critique
6228 Senses cannot judge one another, so what judges senses cannot be a sense, but must be superior [Cudworth]
13. Knowledge Criteria / E. Relativism / 4. Cultural relativism
1490 You would have to be very morally lazy to ignore criticisms of your own culture [Nagel]
17. Mind and Body / E. Mind as Physical / 7. Anti-Physicalism / a. Physicalism critique
6229 Sense is fixed in the material form, and so can't grasp abstract universals [Cudworth]
22. Metaethics / B. Value / 1. Nature of Value / c. Objective value
6227 Keeping promises and contracts is an obligation of natural justice [Cudworth]
25. Social Practice / D. Justice / 2. The Law / c. Natural law
6225 Obligation to obey all positive laws is older than all laws [Cudworth]
28. God / A. Divine Nature / 4. Divine Contradictions
6224 An omnipotent will cannot make two things equal or alike if they aren't [Cudworth]
28. God / A. Divine Nature / 6. Divine Morality / d. God decrees morality
6223 If the will and pleasure of God controls justice, then anything wicked or unjust would become good if God commanded it [Cudworth]
6226 The requirement that God must be obeyed must precede any authority of God's commands [Cudworth]