[FOM] Who was the first to accept undefinable individuals in mathematics?

[praatika@mappi.helsinki.fi]

Quoting "W. Mueckenheim" <mueckenh at rz.fh-augsburg.de>:

> Who was the first mathematician to deliberately accept undefinable
> individuals like real numbers in mathematics?

I think this presupposes rigorous enough picture of definability, so I  
would say: Tarski, in the early 1930s, see e.g. "On definable sets of  
real numbers", 1931.
Before that, people's understanding of the whole theme of definability  
was quite murky...

Best, Panu



Panu Raatikainen

Ph.D., Academy Research Fellow,
Docent in Theoretical Philosophy

Department of Philosophy
University of Helsinki
Finland


E-mail: panu.raatikainen at helsinki.fi

http://www.mv.helsinki.fi/home/praatika/