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Ideas for 'fragments/reports', 'Understanding the Infinite' and 'Investigations into Logical Deduction'

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5 ideas

5. Theory of Logic / A. Overview of Logic / 7. Second-Order Logic

15926

Second-order logic presupposes a set of relations already fixed by the first-order domain [Lavine]

5. Theory of Logic / B. Logical Consequence / 5. Modus Ponens

8078	Modus ponens is one of five inference rules identified by the Stoics [Chrysippus, by Devlin]

5. Theory of Logic / D. Assumptions for Logic / 2. Excluded Middle

6023	Every proposition is either true or false [Chrysippus, by Cicero]

15934

Mathematical proof by contradiction needs the law of excluded middle [Lavine]

5. Theory of Logic / H. Proof Systems / 4. Natural Deduction

13832

Natural deduction shows the heart of reasoning (and sequent calculus is just a tool) [Gentzen, by Hacking]