16960
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If possibilitiy is relative, that might make accessibility non-transitive, and T the correct system [Dummett]
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Full Idea:
If some world is 'a way the world might be considered to be if things were different in a certain respect', that might show that the accessibility relation should not be taken to be transitive, and we should have to adopt modal logic T.
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From:
Michael Dummett (Could There Be Unicorns? [1983], 8)
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A reaction:
He has already rejected symmetry from the relation, for reasons concerning relative identity. He is torn between T and S4, but rejects S5, and opts not to discuss it.
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16958
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In S4 the actual world has a special place [Dummett]
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Full Idea:
In S4 logic the actual world is, in itself, special, not just from our point of view.
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From:
Michael Dummett (Could There Be Unicorns? [1983], 8)
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A reaction:
S4 lacks symmetricality, so 'you can get there, but you can't get back', which makes the starting point special. So if you think the actual world has a special place in modal metaphysics, you must reject S5?
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13267
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Temporal parts is a crazy doctrine, because it entails constantly creating stuff ex nihilo [Thomson, by Koslicki]
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Full Idea:
Thomson famously objects that the doctrine of temporal parts is 'a crazy metaphysic - obviously false', since it entails that material objects are constantly being generated ex nihilo (or, at least, the stuff of which they are composed is).
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From:
report of Judith (Jarvis) Thomson (Parthood and Identity across Time [1983], p.210) by Kathrin Koslicki - The Structure of Objects 2.2
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A reaction:
The related objections are to ask what the temporal 'width' of a part is, and whether the joins are visible.
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16959
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If possible worlds have no structure (S5) they are equal, and it is hard to deny them reality [Dummett]
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Full Idea:
If our space of possible worlds has no structure, as in the semantics for S5, then, from the standpoint of the semantics, all possible worlds are on the same footing; it then becomes difficult to resist the claim that all are equally real.
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From:
Michael Dummett (Could There Be Unicorns? [1983], 8)
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A reaction:
This is a rather startling and interesting claim, given that modern philosophy seems full of thinkers who both espouse S5 for metaphysics, and also deny Lewisian realism about possible worlds. I'll ponder that one. Must read the new Williamson….
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18284
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Particulars can be verified or falsified, but general statements can only be falsified (conclusively) [Popper]
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Full Idea:
Whereas particular reality statements are in principle completely verifiable or falsifiable, things are different for general reality statements: they can indeed be conclusively falsified, they can acquire a negative truth value, but not a positive one.
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From:
Karl Popper (Two Problems of Epistemology [1932], p.256), quoted by J. Alberto Coffa - The Semantic Tradition from Kant to Carnap 18 'Laws'
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A reaction:
This sounds like a logician's approach to science, but I prefer to look at coherence, where very little is actually conclusive, and one tinkers with the theory instead.
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16954
|
Generalised talk of 'natural kinds' is unfortunate, as they vary too much [Dummett]
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Full Idea:
In my view, Kripke's promotion of 'natural kinds', coverning chemical substances and animal and plant species, is unfortunate, since these are rather different types of things, and words used for them behave differently.
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From:
Michael Dummett (Could There Be Unicorns? [1983], 2)
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A reaction:
My view is that the only significant difference among natural kinds is their degree of stability in character. Presumably particles, elements and particular molecules are fairly invariant, but living things evolve.
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