Bolzano, Tarski, and the limits of logic

pp. 13-40

in: Peter Simons, Philosophy and logic in Central Europe from Bolzano to Tarski, Berlin, Springer, 1992

Abstract

[S]ometimes it seems to me convenient to include mathematical terms, like the ∈-relation, in the class of logical ones, and sometimes I prefer to restrict myself to terms of ‘elementary logic’. Is any problem involved here?