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Ideas for 'On Interpretation', 'Reals by Abstraction' and 'Groundwork of the Metaphysic of Morals'

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2 ideas

4. Formal Logic / A. Syllogistic Logic / 1. Aristotelian Logic
Aristotle's later logic had to treat 'Socrates' as 'everything that is Socrates' [Potter on Aristotle]
     Full Idea: When Aristotle moved from basic name+verb (in 'De Interpretatione') to noun+noun logic...names had to be treated as special cases, so that 'Socrates' is treated as short for 'everything that is Socrates'.
     From: comment on Aristotle (On Interpretation [c.330 BCE]) by Michael Potter - The Rise of Analytic Philosophy 1879-1930 02 'Supp'
     A reaction: Just the sort of rewriting that Russell introduced for definite descriptions. 'Twas ever the logicians' fate to shoehorn ordinary speech into awkward containers.
Square of Opposition: not both true, or not both false; one-way implication; opposite truth-values [Aristotle]
     Full Idea: Square of Opposition: horizontals - 'contraries' can't both be true, and 'subcontraries' can't both be false; verticals - 'subalternatives' have downwards-only implication; diagonals - 'contradictories' have opposite truth values.
     From: Aristotle (On Interpretation [c.330 BCE], Ch.12-13)
     A reaction: This is still used in modern discussion (e.g. by Stalnaker against Kripke), and there is a modal version of it (Fitting and Mendelsohn p.7). Corners read: 'All F are G', 'No F are G', 'Some F are G' and 'Some F are not G'.