"In modernism, art becomes a philosophical enterprise rather than an artistic one."
Modern art is a contest of cleverness, a higher-status version of getting a mustache tattoo on your finger. As the author of the article continues,
"The driving purpose of modernism is not to do art but to find out what art is. We have eliminated X —is it still art? Now we have eliminated Y —is it still art? The point of the objects was not aesthetic experience; rather the works are symbols representing a stage in the evolution of a philosophical experiment. In most cases, the discussions about the works are much more interesting than the works themselves. That means that we keep the works in museums and archives and we look at them not for their own sake, but for the same reason scientists keep lab notes—as a record of their thinking at various stages."
This scientific approach to art sounds valid... Until you remember that art is not the Higgs-Boson, and does not need discovering, only defining. Oh, I guess it was just intellectual wank all along.
Postmodern art is the tradition for which Duchamp was the spiritual ancestor - pissing on art itself. Why I wouldn't consider Duchamp to be a postmodern artist ahead of his time is that Duchamp was pissing on modernists, whereas postmodernists are indiscriminate - they will as soon piss on a Pollack or a priceless grand piano.
Postmodernism has made art the vanguard of the Progressive society - ever marching towards the destruction of everything that came before, the abortion of everything that would come after, and the exploitation of everything that is unlucky enough to share its present.