This is what I'm gleaming from the discussion so far.

In your opinion, art needs to be capable of conveying meaning, and a work that is incapable of conveying meaning is not art.

What I'm saying is that since conveyed meaning can only be found by the observer on an individual basis, the classification of what is art and what is not would have to be based on the opinions of a single person, and these opinions would change from person to person. When speaking in broader terms than one person's perspective, this classification is more akin to a division within the category of art itself, and not a division between art and not-art.

This goes back to why I chimed in in the first place. People were of the opinion that Cage's work wasn't art based on their perspectives of the piece. In that position, I may have called the work bad, derivative, confused or any slew of other unflattering labels, but I would not say that it is not art.

This may be a sympathy (or perhaps bias) I have as someone who values the ability to create above almost everything, and there are few things more insulting to me than to be told that something I created, something that I can say I'm proud of, is not art. Call it as many names as you want, but never tell me that it isn't art.