Another point of clarification: I'm all for telling people what sets are. I'm less warm toward discussing things like ZFC, esoteric cardinality issues, and cert

Another point of clarification: I'm all for telling people what sets are. I'm less warm toward discussing things like ZFC, esoteric cardinality issues, and certain paradoxes (and large cardinals, forcing, etc.), which is typically what mathematicians mean when they say "set theory."