Combining Texts

All the ideas for 'On the Law of War and Peace', 'Constructibility and Mathematical Existence' and 'On Second-Order Logic'

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20 ideas

4. Formal Logic / F. Set Theory ST / 8. Critique of Set Theory
8758 We could talk of open sentences, instead of sets [Chihara, by Shapiro]
5. Theory of Logic / A. Overview of Logic / 7. Second-Order Logic
14249 Boolos reinterprets second-order logic as plural logic [Boolos, by Oliver/Smiley]
10830 Second-order logic metatheory is set-theoretic, and second-order validity has set-theoretic problems [Boolos]
5. Theory of Logic / C. Ontology of Logic / 1. Ontology of Logic
10829 A sentence can't be a truth of logic if it asserts the existence of certain sets [Boolos]
5. Theory of Logic / G. Quantification / 2. Domain of Quantification
10832 '∀x x=x' only means 'everything is identical to itself' if the range of 'everything' is fixed [Boolos]
5. Theory of Logic / K. Features of Logics / 4. Completeness
10834 Weak completeness: if it is valid, it is provable. Strong: it is provable from a set of sentences [Boolos]
5. Theory of Logic / K. Features of Logics / 6. Compactness
13841 Why should compactness be definitive of logic? [Boolos, by Hacking]
6. Mathematics / B. Foundations for Mathematics / 4. Axioms for Number / e. Peano arithmetic 2nd-order
10833 Many concepts can only be expressed by second-order logic [Boolos]
6. Mathematics / C. Sources of Mathematics / 6. Logicism / b. Type theory
10265 Chihara's system is a variant of type theory, from which he can translate sentences [Chihara, by Shapiro]
8759 We can replace type theory with open sentences and a constructibility quantifier [Chihara, by Shapiro]
6. Mathematics / C. Sources of Mathematics / 10. Constructivism / a. Constructivism
10264 Introduce a constructibility quantifiers (Cx)Φ - 'it is possible to construct an x such that Φ' [Chihara, by Shapiro]
20. Action / C. Motives for Action / 5. Action Dilemmas / c. Omissions
7404 Nations are not obliged to help one-another, but are obliged not to harm one another [Grotius, by Tuck]
24. Political Theory / A. Basis of a State / 3. Natural Values / c. Natural rights
7402 Everyone has a right of self-preservation, and harming others is usually unjustifiable [Grotius, by Tuck]
24. Political Theory / D. Ideologies / 5. Democracy / a. Nature of democracy
21938 Democracy needs respect for individuality, but the 'community of friends' implies strict equality [Grotius]
25. Social Practice / A. Freedoms / 7. Freedom to leave
19845 A person is free to renounce their state, as long as it is not a moment of crisis [Grotius, by Rousseau]
25. Social Practice / D. Justice / 2. The Law / c. Natural law
22133 Grotius and Pufendorf based natural law on real (rather than idealised) humanity [Grotius, by Ford,JD]
7406 A natural right of self-preservation is balanced by a natural law to avoid unnecessary harm [Grotius, by Tuck]
25. Social Practice / D. Justice / 2. The Law / d. Legal positivism
7403 Grotius ignored elaborate natural law theories, preferring a basic right of self-preservation [Grotius, by Tuck]
25. Social Practice / E. Policies / 1. War / b. Justice in war
23585 It is permissible in a just cause to capture a place in neutral territory [Grotius]
28. God / A. Divine Nature / 6. Divine Morality / b. Euthyphro question
6892 Moral principles have some validity without a God commanding obedience [Grotius, by Mautner]