Are there objective criteria for judging whether or not artworks are good art? Should we at times appeal to moral values in assessing the quality of artwork? What major approaches are there for the purpose of evaluation of art?
Are there objective criteria? There have been theories discussing criteria by which to evaluate artworks; see for example the concise exploration of "Some Theories of Aesthetic Judgment" by Harold Osborne in The Journal of Aesthetics and Art Criticism Vol. 38, No. 2 (Winter, 1979), pp. 135-144. The question of whether any proposed criteria are objective is central aspect of the discussion. If we, for example, take beauty as criterion by which to determine of any artwork whether it is a good artwork, we would be inclined to ask: Is beauty something objective? This is not trivial question and Kant was in pains to show that beauty (or taste) is not (entirely) subjective.
Should we at times appeal to moral values in assessing the quality of artwork? Some reject the idea that morality should play a role in assessing artworks; they maintain that the two realms - the aesthetic and the moral should be kept distinct. However, many who are influenced directly or indirectly by Plato's criticism of art (Republic X), claim that if some artwork is immoral it is not a good art. (Plato, by the way, thought that every art is immoral - in his Ideal Republic there was no room to painters and poets).(The subject of course is too broad to cover here).
My personal belief is that there ARE objective aesthetic criteria.
But there is no one set of these criteria that is universally, or even widely accepted. There are, however innumerable competing theories. It would be impossible to give an exhaustive list, but here are some rough glosses on a few of the most prominent and/or distinctive (several of which do, in fact, draw a connection between moral and aesthetic concerns):
Platonic: Art is what best expresses or orients us towards ideal Beauty, which is perfect, immutable, and transcendent.
Confucian: Art is the product of cultivation and study, a demonstration of virtue at work.
Aristotelian: Art plays a function in helping us understand the world and regulate ourselves.
Kantian: Art is a practice that conveys a profound sense of purpose without actually being functional.
Taoist: Art embodies the balance found in nature.
Existential: Art is a form of individual expression that reveals the universal within the specific.
Empirical / Taste Theory: Art is what people like.
Dantonian: Art is the material production of the artistic matrix within the artistic context.
As you can see, any given theory of art has a deep relationship with the philosophy that created it. In a sense, it IS that philosophy, as written upon the objects of the world. But the question of which aesthetic is superior, and therefore of which piece of art is superior, is as contentious as the question of which philosophy is correct.
Absolutely! -- beauty IS objective.
In fact, beauty can be described in purely mathematical terms -- just like music can be described through math.
Our brain is a neural network (NN) conglomerate -- a bunch of neural nets working together to run a human. All of our automatic responses,¹ from Autonomic Nervous System to keeping balance while walking, to everything real-time, including social interactions, is controlled by some neural net.²
What does that mean in practical terms?
Neural nets are irrational, they have no capacity for understanding, explanation, or knowledge (i.e. they know nothing for sure). They are probabilistic (Bayesian) and superficial in nature, trying to guess what is going on and what to do next.
Now choosing what to do next often means picking the most efficient solution. Except NN can't model different solutions to compare their efficiency (as the rational mind would). What NNs have instead, is their sense of beauty.
"Beauty" is a neural net's idea of "efficiency".
And as everything else about NN, it can be described through Bayesian extensions to information theory. Details are in this paper:
Bayesian Beauty: On the ART of EVE’ and the Act of Enjoyment by Kevin Burns.
¹ ..and everything we do in real-time, including social interactions, is automatic
² Aside from pure neural nets, human and animal brains have a sensory-associative structure that is responsible for logic and reasoning. Its high-level design and operational principle are very different from a neural net.