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] |
12887 | A whole must have one characteristic, an internal relation, and a structure [Rescher/Oppenheim] |
7803 | Modal logic began with translation difficulties for 'If...then' [Lewis,CI, by Girle] |