Is art a thing of the past?

In one of the sections of the introduction to the textbook, Wartenberg asks, "Is Contemporary Art Still Art?"  He goes on to quote the character Marc from the Yasmina Reza play, Art, who speaks of contemporary art's rules of "novelty" and "surprise."  True, not every painting done today is in the contemporary style, which does not seem to represent anything more solid than a thought or emotion.  Perhaps my title is unnecessarily sensational (sorry).
For example, look at this Caravaggio painting, The Conversion of St. Paul.

And then, this painting by Steven Stone, Marea:

The first image obviously depicts a scene, complete with three-dimensional perspective and dramatic areas of light and shadow.  The second is rather abstract--colorful and comprised of shapes and lines reminiscent of a collage, but the subject is not clear.  Does the Caravaggio qualify as art more so than the Steven Stone painting (or vice versa)?

This brings me to my question: What kind of role does representation play in the classification of art?


Images: http://www.albany.edu/scj/jcjpc/figures/st-paul.jpg
http://tedmikulski.files.wordpress.com/2010/02/1_front.jpg