>>11193516>>11193537I see. Well if I'd have to make another guess, I'd say he was very interested in their axiomatization - after all he was at uni before his 20's, part of the rationalist Vienna circle and afaik also into Kant (we can talk about that more in detail if you like) - and He took on Hilberts quest for completeness in his 20's, so I see no point at which he was casual enough for adopting primitives of such an easy to axiomatize theory. Freges work on second order axioms of natural number arithmetic was over 50 years old by then. I live 10 minutes from the cafe where Gödel did his major first work btw.
