5 ideas
17832 | Zermelo showed that the ZF axioms in 1930 were non-categorical [Zermelo, by Hallett,M] |
13028 | Replacement was added when some advanced theorems seemed to need it [Zermelo, by Maddy] |
17626 | The antinomy of endless advance and of completion is resolved in well-ordered transfinite numbers [Zermelo] |
18256 | Quantity is inconceivable without the idea of addition [Frege] |
9831 | Geometry appeals to intuition as the source of its axioms [Frege] |