Combining Texts

All the ideas for 'What is Logic?st1=Ian Hacking', 'Preface to 'Dorian Gray'' and 'Enquiry concerning Principles of Morals'

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27 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
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]
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]
21. Aesthetics / C. Artistic Issues / 6. Value of Art
7276 All art is quite useless [Wilde]
21. Aesthetics / C. Artistic Issues / 7. Art and Morality
7274 Books are only well or badly written, not moral or immoral [Wilde]
7275 Having ethical sympathies is a bad mannerism of style in an artist [Wilde]
22. Metaethics / B. Value / 2. Values / f. Altruism
3926 The human heart has a natural concern for public good [Hume]
23. Ethics / A. Egoism / 1. Ethical Egoism
3929 No moral theory is of any use if it doesn't serve the interests of the individual concerned [Hume]
23. Ethics / C. Virtue Theory / 1. Virtue Theory / a. Nature of virtue
3925 Personal Merit is the possession of useful or agreeable mental qualities [Hume]
23. Ethics / C. Virtue Theory / 3. Virtues / c. Justice
3922 Justice only exists to support society [Hume]
23560 If we all naturally had everything we could ever desire, the virtue of justice would be irrelevant [Hume]
23. Ethics / D. Deontological Ethics / 2. Duty
3918 Moral philosophy aims to show us our duty [Hume]
23. Ethics / D. Deontological Ethics / 6. Motivation for Duty
3919 Conclusions of reason do not affect our emotions or decisions to act [Hume]
23. Ethics / E. Utilitarianism / 1. Utilitarianism
3928 Virtue just requires careful calculation and a preference for the greater happiness [Hume]
23. Ethics / E. Utilitarianism / 3. Motivation for Altruism
3923 No one would cause pain to a complete stranger who happened to be passing [Hume]
3924 Nature makes private affections come first, because public concerns are spread too thinly [Hume]
24. Political Theory / B. Nature of a State / 1. Purpose of a State
3921 The safety of the people is the supreme law [Hume]
24. Political Theory / C. Ruling a State / 3. Government / a. Government
3927 Society prefers helpful lies to harmful truth [Hume]
25. Social Practice / B. Equalities / 4. Economic equality
3920 If you equalise possessions, people's talents will make them unequal again [Hume]