Combining Texts

All the ideas for 'Leibniz', 'Letters to William Molyneux' and 'Science and Method'

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3 ideas

6. Mathematics / A. Nature of Mathematics / 2. Geometry
One geometry cannot be more true than another [Poincaré]
     Full Idea: One geometry cannot be more true than another; it can only be more convenient.
     From: Henri Poincaré (Science and Method [1908], p.65), quoted by Stewart Shapiro - Philosophy of Mathematics
     A reaction: This is the culminating view after new geometries were developed by tinkering with Euclid's parallels postulate.
9. Objects / D. Essence of Objects / 13. Nominal Essence
Things have real essences, but we categorise them according to the ideas we receive [Locke]
     Full Idea: This I do say, that there are real constitutions in things from whence simple ideas flow, which we observe combin'd in them. But we distinguish particular substances into sorts or genera not by real essences or constitutions, but by observed simple ideas.
     From: John Locke (Letters to William Molyneux [1692], 1693.01.20)
     A reaction: This is the clearest statement I can find of Locke's position on essences. He is totally committed to their reality, but strongly aware of the empirical constraints which keep us from direct knowledge of them. He would be amazed by modern discoveries.
9. Objects / F. Identity among Objects / 7. Indiscernible Objects
The Identity of Indiscernibles is really the same as the verification principle [Jolley]
     Full Idea: Various writers have noted that the Identity of Indiscernibles is really tantamount to the verification principle.
     From: Nicholas Jolley (Leibniz [2005], Ch.3)
     A reaction: Both principles are false, because they are the classic confusion of epistemology and ontology. The fact that you cannot 'discern' a difference between two things doesn't mean that there is no difference. Things beyond verification can still be discussed.