Didn't he kind of miss the point of his own article at one point? He expressly says that the cave painters of old were:
They were great artists at that time, geniuses with nothing to build on, and were not in the process of becoming Michelangelo or anyone else.
So by making something from nothing you area genius, how then when you create your own definition of art by:
but then you are creating your own art object from the materials at hand.
Are you not doing exactly the same thing? If what the cave painters did was art because they took nothing and made it something, then if we take the same approach in our definition of art, we must also be geniuses. Thanks Mr Ebert, but I think you may be confusing yourself.
Also, as a linguist of sorts, I take exception to the view that Roger Ebert thinks he can define art to any reasonable standard. That's not his prerogative, and I have just as much backing as he does to be able to deem something art as well.
In short, he's elitist and I don't agree with him.