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3 ideas
| 18253 | I wish to go straight from cardinals to reals (as ratios), leaving out the rationals [Frege] |
| Full Idea: You need a double transition, from cardinal numbes (Anzahlen) to the rational numbers, and from the latter to the real numbers generally. I wish to go straight from the cardinal numbers to the real numbers as ratios of quantities. | |
| From: Gottlob Frege (Letters to Russell [1902], 1903.05.21), quoted by Michael Dummett - Frege philosophy of mathematics 21 'Frege's' | |
| A reaction: Note that Frege's real numbers are not quantities, but ratios of quantities. In this way the same real number can refer to lengths, masses, intensities etc. |
| 12688 | Mathematics is the formal study of the categorical dimensions of things [Ellis] |
| Full Idea: I wish to explore the idea that mathematics is the formal study of the categorical dimensions of things. | |
| From: Brian Ellis (The Metaphysics of Scientific Realism [2009], 6) | |
| A reaction: Categorical dimensions are spatiotemporal relations and other non-causal properties. Ellis defends categorical properties as an aspect of science. The obvious connection seems to be with structuralism in mathematics. Shapiro is sympathetic. |
| 18166 | The loss of my Rule V seems to make foundations for arithmetic impossible [Frege] |
| Full Idea: With the loss of my Rule V, not only the foundations of arithmetic, but also the sole possible foundations of arithmetic, seem to vanish. | |
| From: Gottlob Frege (Letters to Russell [1902], 1902.06.22) | |
| A reaction: Obviously he was stressed, but did he really mean that there could be no foundation for arithmetic, suggesting that the subject might vanish into thin air? |