Full Idea
It is possible for a truth to be an axiom in one system and not in another.
Gist of Idea
A truth can be an axiom in one system and not in another
Source
Gottlob Frege (Logic in Mathematics [1914], p.205)
Book Reference
Frege,Gottlob: 'Posthumous Writings', ed/tr. Hermes/Long/White etc [Blackwell 1979], p.205
A Reaction
Frege aspired to one huge single system, so this is a begrudging concession, one which modern thinkers would probably take for granted.
Related Idea
Idea 16869 To create order in mathematics we need a full system, guided by patterns of inference [Frege]