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2 ideas
| 16504 | Two eggs can't be identical, because the same truths can't apply to both of them [Leibniz] |
| Full Idea: It isn't possible to have two particulars that are similar in all respects - for example two eggs - for it is necessary that some things can be said about one of them that cannot be said about the other, else they could be substituted for one another. | |
| From: Gottfried Leibniz (works [1690]), quoted by David Wiggins - Sameness and Substance 2.2 | |
| A reaction: [from a 'fragment' for which Wiggins gives a reference] This quotation doesn't rest the distinctness of the eggs on some intrinsic difference, but on the fact that we can say different things about the two eggs. |
| 8650 | Things are the same if one can be substituted for the other without loss of truth [Leibniz] |
| Full Idea: Leibniz's definition is as follows: Things are the same as each other, of which one can be substituted for the other without loss of truth ('salva veritate'). | |
| From: Gottfried Leibniz (works [1690]), quoted by Gottlob Frege - Grundlagen der Arithmetik (Foundations) §65 | |
| A reaction: Frege doesn't give a reference. (Anyone know it?). This famous definition is impressive, but has problems when the items being substituted appear in contexts of belief. 'Oedipus believes Jocasta (his mother!) would make a good wife'. |