Aesthetic realism is the belief that there are things that are objectively more beautiful than other things. This implies beauty is not subjective, and if one believes an actually beautiful thing is ugly, he is simply incorrect (perhaps more charitably, he is not perceiving the beauty which is actually there).
Aesthetic realism has roots as early as Plato. It was at least common in medieval times and during the Renaissance in the West. Historically speaking, at this time, it was entangled with religious assumptions that were partially influenced by Platonism.
I can think of very few philosophies that are less popular in modern times. Are there any rational, non-religious* arguments in favor of aesthetic realism?
*I don’t mind if there are religious arguments so long as they are rational, not reliant on haphazard assumptions whose truth is even more suspect, and not reliant on the truth of Christian thought in particular (I consider this haphazard).