Combining Texts

All the ideas for 'Letters to Edward Stillingfleet', 'Letters to Thomasius' and 'Ontological Ground of Alethic Modality'

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5 ideas

9. Objects / D. Essence of Objects / 1. Essences of Objects

13432	The essence of a circle is the equality of its radii [Leibniz]
	Full Idea: The essence of a circle consists in the equality of all lines drawn from its centre to its circumference.
	From: Gottfried Leibniz (Letters to Thomasius [1669], 1669)
	A reaction: Compare Locke in Idea 13431 and Spinoza in Idea 13073 on the essence of geometrical figures. A key question is whether the essence is in the simplest definition, or in a complex and wide-ranging account, e.g. including conic sections for circles.

9. Objects / D. Essence of Objects / 3. Individual Essences

15990	Every individual thing which exists has an essence, which is its internal constitution [Locke]
	Full Idea: I take essences to be in everything that internal constitution or frame for the modification of substance, which God in his wisdom gives to every particular creature, when he gives it a being; and such essences I grant there are in all things that exist.
	From: John Locke (Letters to Edward Stillingfleet [1695], Letter 1), quoted by Simon Blackburn - Quasi-Realism no Fictionalism
	A reaction: This is the clearest statement I have found of Locke's commitment to essences, for all his doubts about whether we can know such things. Alexander says (ch.13) Locke was reacting against scholastic essence, as pertaining to species.

10. Modality / E. Possible worlds / 1. Possible Worlds / e. Against possible worlds

9220	Lewis must specify that all possibilities are in his worlds, making the whole thing circular [Shalkowski, by Sider]
	Full Idea: If purple cows are simply absent from Lewis's multiverse, then certain correct propositions turn out to be impossible. Lewis must require a world for every possibility. But then it is circular, as the multiverse needs modal notions to characterize it.
	From: report of Scott Shalkowski (Ontological Ground of Alethic Modality [1994], 3.9) by Theodore Sider - Reductive Theories of Modality 3.9
	A reaction: [Inversely, a world containing a round square would make that possible] This sounds very nice, though Sider rejects it (p.197). I've never seen how you could define possibility using the concept of 'possible' worlds.

11. Knowledge Aims / B. Certain Knowledge / 1. Certainty

15994	If it is knowledge, it is certain; if it isn't certain, it isn't knowledge [Locke]
	Full Idea: What reaches to knowledge, I think may be called certainty; and what comes short of certainty, I think cannot be knowledge.
	From: John Locke (Letters to Edward Stillingfleet [1695], Letter 2), quoted by Simon Blackburn - Quasi-Realism no Fictionalism
	A reaction: I much prefer that fallibilist approach offered by the pragmatists. Knowledge is well-supported belief which seems (and is agreed) to be true, but there is a small shadow of doubt hanging over all of it.

27. Natural Reality / A. Classical Physics / 1. Mechanics / a. Explaining movement

12696	Bodies are recreated in motion, and don't exist in intervening instants [Leibniz]
	Full Idea: I have demonstrated that whatever moves is continuously created and that bodies are nothing at any time between the instants in motion.
	From: Gottfried Leibniz (Letters to Thomasius [1669], 1669.04), quoted by Daniel Garber - Leibniz:Body,Substance,Monad 1
	A reaction: Leibniz is a little over-confident about what he has 'demonstrated', but I think (from this remark) that he would not have been displeased with quantum theory, and the notion of a 'quantum leap' and a 'Planck time'. A 'conatus' is a 'smallest motion'.