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Ideas for 'fragments/reports', 'The Laws of Thought' and 'Review of Husserl's 'Phil of Arithmetic''

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3 ideas

6. Mathematics / C. Sources of Mathematics / 1. Mathematical Platonism / a. For mathematical platonism
Our concepts recognise existing relations, they don't change them [Frege]
     Full Idea: The bringing of an object under a concept is merely the recognition of a relation which previously already obtained, [but in the abstractionist view] objects are essentially changed by the process, so that objects brought under a concept become similar.
     From: Gottlob Frege (Review of Husserl's 'Phil of Arithmetic' [1894], p.324)
     A reaction: Frege's view would have to account for occasional misapplications of concepts, like taking a dolphin to be a fish, or falsely thinking there is someone in the cellar.
Numbers are not real like the sea, but (crucially) they are still objective [Frege]
     Full Idea: The sea is something real and a number is not; but this does not prevent it from being something objective; and that is the important thing.
     From: Gottlob Frege (Review of Husserl's 'Phil of Arithmetic' [1894], p.337)
     A reaction: This seems a qualification of Frege's platonism. It is why people start talking about abstract items which 'subsist', instead of 'exist'. It shows Frege's motivation in all this, which is to secure logic and maths from the vagaries of psychology.
6. Mathematics / C. Sources of Mathematics / 4. Mathematical Empiricism / c. Against mathematical empiricism
The naïve view of number is that it is like a heap of things, or maybe a property of a heap [Frege]
     Full Idea: The most naïve opinion of number is that it is something like a heap in which things are contained. The next most naïve view is the conception of number as the property of a heap, cleansing the objects of their particulars.
     From: Gottlob Frege (Review of Husserl's 'Phil of Arithmetic' [1894], p.323)
     A reaction: A hundred toothbrushes and a hundred sponges can be seen to contain the same number (by one-to-one mapping), without actually knowing what that number is. There is something numerical in the heap, even if the number is absent.