6 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] |
18758 | Validity is provable, but invalidity isn't, because the model is infinite [Church, by McGee] |
17626 | The antinomy of endless advance and of completion is resolved in well-ordered transfinite numbers [Zermelo] |
2614 | Modern phenomenalism holds that objects are logical constructions out of sense-data [Ayer] |
2615 | The concept of sense-data allows us to discuss appearances without worrying about reality [Ayer] |