I've just finished reading Emma Darwin's excellent novel, A Secret Alchemy and very much enjoyed it, perhaps even more so because it's not the kind of book I would normally read. If you give it a try it's important to persevere - I got a bit confused to begin with by a combination of multi-threading and a whole host of historical characters whose names meant little to me, but if you go with the flow and give the author a chance, it's well worth the effort.
One small segment in it particularly caught my eye: Craft is art made possible, I think suddenly: possible and functional. Art that feeds and clothes and houses. This really interested me. When I'm not taking a modern view of art (mostly worthless rubbish), I tend to the medieval, when the question with which I started this post was meaningless. Art was the output of artifice. It was anything man made as opposed to natural. So when on Top Gear a while ago they tried to present a car as art to a bunch of art professors, and the academics dismissed it because it had a function, I have, with my medieval hat on to shake my head sadly. Of course it's art. It hardly grew on a bush.
What's interesting if you do take the 'craft is art with a function' view, then it seems logical that art does not have a function. And maybe that's where art has gone so wrong in the last 100 years. It always used to have a function. Medieval art either did something practical, pleased the eye or was to the glory of God (or any combination of the three). Some modern 'art' does cover one or more of these functions but much of it doesn't. In reality, I would suggest, there are two categories of unnatural product. Not art and craft, but art and garbage. Both are made by human beings. One has a function, the other doesn't.