I also mentioned that Jackson Pollock's name had been mentioned in this regard, and now I want to return to that, and as a result propose one further criterion.I do not like Pollock's work. I find it does not move me; I am not sure what it is trying to do, and therefore cannot evaluate how well it does it. I question whether it really demonstrates any skill, or any insight. So, in my judgement, it does not meet many of the criteria I proposed. However, I also recognise that all of that is a subjective perspective, and at least in part based on my ignorance. Others clearly think it is art of stature.
I compare my reaction to Pollock with my reaction to Mondrian. At first glance, I had a similar view of Mondrian's work; but the more I see of it, (particularly originals - his work does not reproduce well, I find) the more I question that. I think he really is onto something, though I would struggle to say what.But again, I recognise that is a subjective view. And there is (a large) part of me that wonders if most modern art has lost its way, and is pulling a fast one, as it were. And that too is a subjective view.
So I am prepared to hold fire, and not have a strong opinion (well, I do on Tracey Emin and Damien Hirst, but the less said about them, the better). Nor do I find there are many cultural or artistic critics in whom I have sufficient confidence to accept their judgements pro or contra.
The same is true of some modern music: serialism does nothing for me, for example. But that may be a failing in me, not least due to a lack of education and understanding.
But the most important additional criterion, I think, is the judgment of time. Artistic judgements are subject to fashion. Even Shakespeare was out of vogue for a period, and during the Restoration there was a marked trend to improve his plays to conform to current tastes. But over time that shakes down: the genius of Beethoven or Van Gogh is clearer with historical perspective.
So I am happy to remain agnostic about Pollock and Mondrian, and let our descendants be the judges. But that does not, I think, detract from my central thesis that one can make objective statements about the quality of art. It just suggests that education, understanding and perspective may all be necessary in order to do so.