14238
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A class is an aggregate of objects; if you destroy them, you destroy the class; there is no empty class [Frege]
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Full Idea:
A class consists of objects; it is an aggregate, a collective unity, of them; if so, it must vanish when these objects vanish. If we burn down all the trees of a wood, we thereby burn down the wood. Thus there can be no empty class.
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From:
Gottlob Frege (Elucidation of some points in E.Schröder [1895], p.212), quoted by Oliver,A/Smiley,T - What are Sets and What are they For?
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A reaction:
This rests on Cantor's view of a set as a collection, rather than on Dedekind, which allows null and singleton sets.
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24043
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Soul must be immortal, since it continually moves, like the heavens [Alcmaeon, by Aristotle]
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Full Idea:
Alcmaeon says that the soul is immortal because it resembles immortal things and that this affection belongs to it because it is always in movement, like divine things, such the moon, the sun, the stars and the whole heaven.
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From:
report of Alcmaeon (fragments/reports [c.490 BCE], DK 24) by Aristotle - De Anima 405a30
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A reaction:
Hm. Fish and rivers seem to be continually moving too. Presumably we are like gods, but then Greek gods seem awfully like humans. I don't know the history of belief in immortality; an interesting topic.
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