Combining Texts

All the ideas for 'Laches', 'Building Blocks of Mathematical Logic' and 'A Completeness Theorem in Modal Logic'

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7 ideas

1. Philosophy / A. Wisdom / 3. Wisdom Deflated

291	Don't assume that wisdom is the automatic consequence of old age [Plato]

4. Formal Logic / D. Modal Logic ML / 1. Modal Logic

10163

Propositional modal logic has been proved to be complete [Kripke, by Feferman/Feferman]

4. Formal Logic / D. Modal Logic ML / 3. Modal Logic Systems / a. Systems of modal logic

10760

With possible worlds, S4 and S5 are sound and complete, but S1-S3 are not even sound [Kripke, by Rossberg]

4. Formal Logic / D. Modal Logic ML / 7. Barcan Formula

16189

The variable domain approach to quantified modal logic invalidates the Barcan Formula [Kripke, by Simchen]

15132

The Barcan formulas fail in models with varying domains [Kripke, by Williamson]

5. Theory of Logic / E. Structures of Logic / 4. Variables in Logic

17699

Variables are auxiliary notions, and not part of the 'eternal' essence of logic [Schönfinkel]

23. Ethics / C. Virtue Theory / 3. Virtues / d. Courage

293	Being unafraid (perhaps through ignorance) and being brave are two different things [Plato]