arthur danto

"In periods of artistic stability, there can be little doubt that works of art very frequently were found to have properties, the failure of which would call seriously into question their status as artworks. but that time has long passed, and just as anything can be an expression of anything, provided we know the conventions under which it is one and the causes through which its status as an expression is to be explained, so in this sense can anything be a work of art. Of course it does not follow from the fact that anything can be a work of art that everything is one. The typewriter I am writing on could have been a work of art, but it happens not to be one. What makes art so interesting a concept is that in nothing like the sense in which my typewriter could be a work of art could it be a ham sandwich, through of course some ham sandwich could be, and perhaps already is, a work of art."

(from The Transfiguration of the Commonplace)