I'm pretty sure biology falls within the S in STEM. "Guns, Germs, and Steel" is a pop-science book, surely you could have used a more literary example to represent "the arts."
"The arts" was probably a bad choice of words, because few people are brazen enough to say art isn't good. Instead they'll say art is a good hobby, surely you can program by day and still write some little operas or something at night. Of course, this completely understates the dedication and focus required to produce a work.
I really wanted to defend the soft sciences: psychology, socioligy , anthro, and other things people on HN don't see the need for.