Symptoms of art?

This past week in class we discussed the symptoms of what makes something art. The list of symptoms are as follows...

-Syntactic density- finest differences constitute, differences in symbolization.
-Symantec density- functioning differently, but the meaning if them functions differently is different.
-Relative repleteness- allot of differences at once.

These are the symptoms of what makes art. However, presenence of absence of these does not prove anything. These are just symptoms. They do not prove what art is.

Therefore the question i pose is how do you recognize anything without symptoms? It is either art or not?