Combining Texts

Ideas for 'Parmenides', 'Db (chronology)' and 'Rules for the Direction of the Mind'

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3 ideas

6. Mathematics / A. Nature of Mathematics / 4. Using Numbers / a. Units
Unity is something shared by many things, so in that respect they are equals [Descartes]
     Full Idea: Unity is that common nature in which all things that are compared with each other must participate equally.
     From: René Descartes (Rules for the Direction of the Mind [1628], 14)
     A reaction: A lovely explanation of the concept of 'units' for counting. Fregeans hate units, but we Grecian thinkers love them.
I can only see the proportion of two to three if there is a common measure - their unity [Descartes]
     Full Idea: I do not recognise what the proportion of magnitude is between two and three, unless I consider a third term, namely unity, which is the common measure of the one and the other.
     From: René Descartes (Rules for the Direction of the Mind [1628], 14)
     A reaction: A striking defence of the concept of the need for the unit in arithmetic. To say 'three is half as big again', you must be discussing the same size of 'half' in each instance.
6. Mathematics / C. Sources of Mathematics / 1. Mathematical Platonism / a. For mathematical platonism
One is, so numbers exist, so endless numbers exist, and each one must partake of being [Plato]
     Full Idea: If one is, there must also necessarily be number - Necessarily - But if there is number, there would be many, and an unlimited multitude of beings. ..So if all partakes of being, each part of number would also partake of it.
     From: Plato (Parmenides [c.364 BCE], 144a)
     A reaction: This seems to commit to numbers having being, then to too many numbers, and hence to too much being - but without backing down and wondering whether numbers had being after all. Aristotle disagreed.