Combining Philosophers

Ideas for Herodotus, Ren Descartes and Robert Hanna

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7 ideas

10. Modality / A. Necessity / 2. Nature of Necessity

11083

A sentence is necessary if it is true in a set of worlds, and nonfalse in the other worlds [Hanna]

10. Modality / A. Necessity / 5. Metaphysical Necessity

11086

Metaphysical necessity can be 'weak' (same as logical) and 'strong' (based on essences) [Hanna]

10. Modality / A. Necessity / 6. Logical Necessity

11084

Logical necessity is truth in all logically possible worlds, because of laws and concepts [Hanna]

10. Modality / A. Necessity / 7. Natural Necessity

11085

Nomological necessity is truth in all logically possible worlds with our laws [Hanna]

10. Modality / C. Sources of Modality / 4. Necessity from Concepts

24030

3+4=7 is necessary because we cannot conceive of seven without including three and four [Descartes]

10. Modality / D. Knowledge of Modality / 1. A Priori Necessary

2301	We know by thought that what is done cannot be undone [Descartes]

10. Modality / D. Knowledge of Modality / 4. Conceivable as Possible / b. Conceivable but impossible

3642	Pythagoras' Theorem doesn't cease to be part of the essence of triangles just because we doubt it [Arnauld on Descartes]