In December 1950, he joined the government funded American Committee for Cultural Freedom. Greenberg believed Modernism provided a "critical" commentary on experience. It was constantly changing to adapt to kitsch pseudo-culture, which was itself always developing. In the years after World War II, Greenberg pushed the position that the best avant-garde artists were emerging in America rather than Europe. Particularly, he championed Jackson Pollock as the greatest painter of his generation, commemorating the artist's "all-over" gestural canvases. In the 1955 essay "American-Type Painting" Greenberg promoted the work of Abstract Expressionists, among them Jackson Pollock, Willem de Kooning, Hans Hofmann, Barnett Newman, and Clyfford Still, as the next stage in Modernist art, arguing that these painters were moving towards greater emphasis on the 'flatness' of the picture plane.