Combining Texts

Ideas for 'Parmenides', 'Difficulties of Transfinite Numbers and Types' and 'What is Property?'

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3 ideas

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.
6. Mathematics / C. Sources of Mathematics / 10. Constructivism / d. Predicativism
We need rules for deciding which norms are predicative (unless none of them are) [Russell]
     Full Idea: We need rules for deciding what norms are predicative and what are not, unless we adopt the view (which has much to recommend it) that no norms are predicative. ...[146] A predative propositional function is one which determines a class.
     From: Bertrand Russell (Difficulties of Transfinite Numbers and Types [1905], p.141)
     A reaction: He is referring to his 'no class' theory, which he favoured at that time.
'Predicative' norms are those which define a class [Russell]
     Full Idea: Norms (containing one variable) which do not define classes I propose to call 'non-predicative'; those which do define classes I shall call 'predicative'.
     From: Bertrand Russell (Difficulties of Transfinite Numbers and Types [1905], p.141)