 The tenability of logicism has been disputed on multiple grounds, the most prominent of which is that the notion of membership fundamental to the theory of sets is not a logical notion but rather a symbol that must be added to first-order logic to formalize what is properly understood as a non-logical theory. Nor would philosophers today accept the conception of the axioms of set theory as logical axioms, since there exist alternatives. So even if mathematics were reducible to set theory, these considerations undermine Hempel’s claim that mathematics is thereby reducible to logic (cf. Benacerraf 1981 and Linsky &amp; Zalta 2006, which provides an extensive bibliography). Hempel’s views about geometry, in retrospect, thus appear to have been the better founded.