I know you're all sick of this topic, but I'm going to do the "art" thing one more time. I just heard someone say yesterday that teaching was both an art and a science, and the light bulb went on over my head (the fact that I was interviewing someone for a job at the time went off to the side while I thought about art and science for a couple of minutes...)
Everybody, it seems, wants to describe their work as "both an art and a science." Medicine is the science of biology combined with the art of diagnosis and bedside manner; teaching is the science of pedagogy and the art of classroom interaction; politics is the science of polling and the art of connection and persuasion; blah blah blah. I think that all of these usages are just failures of vocabulary, imagining that all human endeavors have to fall in one of those two categories because there aren't any others.
Let's have a richer array of possibilities, please. Let's imagine that there are a great number of ways of interacting with the world -- science, yes of course, and art too, but also craft, design, interpretation, advocacy, and translation (at least -- probably lots of others). Just because some action relies on firm knowledge or responds to the physical world doesn't make it a science, and just because it requires discretion and judgment doesn't make it an art.