With modernism, the conditions of representation themselves become central, so that art in a way becomes its own subject. This was almost precisely the way in which Clement Greenberg defined the matter in his famous 1960 essay "Modernist Painting." "The essence of modernism," he wrote, "lies, as I see it, in the use of the characteristic methods of a discipline to criticize the discipline itself, not in order to subvert it but in order to entrench it more firmly in its area of competence." Interestingly, Greenberg took as his model of modernist thought the philosopher Immanuel Kant: "Because he was the first to criticize the means itself of criticism, I conceive of Kant as the first real Modernist." Kant did not see philosophy as adding to our knowldge so much as answering the question of how knowledge was possible.
After the End of Art, Arthur C. Danto