What Is Art?

A friend of mine and I were discussing Art and qualifications to be such. We resolved our issue in stating that art is something that can make a persons mind evoke thought of likes, dislikes, and other emotions. His argument prior to that was that a flaming bag of dog poo on the driveway was not a prank then, but(t) art as it invokes emotion and reaction. I am still working on a response to this, however I also do not expect to see some remove a print of a photograph that I have taken and stomp the living daylights (or nightlights) out of it. What are some of your feelings of what constitutes art? Hmmmm…