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Ideas for 'fragments/reports', 'De Re and De Dicto' and 'Letters to Bentley'

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3 ideas

6. Mathematics / A. Nature of Mathematics / 3. Nature of Numbers / a. Numbers
We can talk of 'innumerable number', about the infinite points on a line [Newton]
     Full Idea: If any man shall take the words number and sum in a larger sense, to understand things which are numberless and sumless (such as the infinite points on a line), I could allow him the contradictious phrase 'innumerable number' without absurdity.
     From: Isaac Newton (Letters to Bentley [1692], 1693.02.25)
     A reaction: [compressed] I take the key point here to be the phrase of taking number 'in a larger sense'. Like the word 'atom' in physics, the word 'number' retains its traditional reference, but has considerably shifted its scope. Amateurs must live with this.
6. Mathematics / A. Nature of Mathematics / 3. Nature of Numbers / g. Real numbers
Could I name all of the real numbers in one fell swoop? Call them all 'Charley'? [Plantinga]
     Full Idea: Can't I name all the real numbers in the interval (0,1) at once? Couldn't I name them all 'Charley', for example?
     From: Alvin Plantinga (De Re and De Dicto [1969], p.40)
     A reaction: Plantinga is nervous about such a sweeping move, but can't think of an objection. This addresses a big problem, I think - that you are supposed to accept the real numbers when we cannot possibly name them all.
6. Mathematics / A. Nature of Mathematics / 5. The Infinite / a. The Infinite
Not all infinites are equal [Newton]
     Full Idea: It is an error that all infinites are equal.
     From: Isaac Newton (Letters to Bentley [1692], 1693.01.17)
     A reaction: There follows a discussion of the mathematicians' view of infinity. Cantor was not the first to notice that there is more than one sort of of infinity.