As a follow-up to my notes on Peter Schjeldahl's lecture, I suggest you read Umberto Eco's article (Notions of beauty, October 2) for The Guardian, a section of an essay in his new book, On Beauty, translated by Alastair McEwen:
We cannot look at things from such a distance; all we can do is content ourselves with noting that the first half of the 20th century, up to and including the 1960s at most (after which it would be more difficult), witnessed a dramatic struggle between the beauty of provocation and the beauty of consumption. The beauty of provocation is the idea of beauty that emerged from the various avant-garde movements and from artistic experimentalism: from futurism to cubism, from expressionism to surrealism, and from Picasso to the great masters of informal art and beyond. Avant-garde art does not itself pose the problem of beauty.While Schjeldahl called abstract art "an exploration of the decorative side of art," Eco says that "this 'neo-pythagorical' return to the aesthetics of proportion works against current sensibilities, against the ideas ordinary people have about beauty." Check it out.