Background
The predominant term for art produced since the 1950s is Contemporary Art. Not all art labeled 'contemporary' is modern or postmodern, and the term contemporary encompasses both artists who continue to work in modernist or late modernist traditions, as well as artists who reject modernism for post-modernism or other reasons. Arthur Danto argues explicitly in After the End of Art that contemporaneity is the broader term, and that postmodern objects represent a sub-sector of the contemporary movement which replaced modernity and modernism.
Radical movements in modern art
Modern art, radical movements in Modernism, and radical trends regarded as influential and potential precursors to late modernism and postmodernism emerged around World War I and particularly in its aftermath. With the introduction of the use of industrial artifacts in art came movements such as Cubism, Dada, and Surrealism as well as techniques such as collage and art forms such as cinema and the rise of reproduction as a means of creating artworks. Pablo Picasso, Marcel Duchamp, and many others created important and influential works from found objects.
Pablo Picasso, Les Demoiselles d'Avignon, 1907
This work by Picasso is considered to be a major step towards the founding of the Cubist movement.
Late Modernism vs. Postmodernism
The discourse surrounding the terms Late Modernism and Postmodern art is fraught with many differing opinions. There are those who argue against any division into modern and postmodern periods. Some don't believe that the period called modernism is over or even near the end, and there certainly is no agreement that all art after modernism is post-modern, nor that postmodern art is universally separated from modernism; many critics see it as merely another phase in modern art or another form of late Modernism. There is, however, a consensus that a profound change in the perception of works of art, and works of art themselves, has occurred and that a new era has been emerging on the world stage since at least the 1960s.
Late modernism describes movements which arose from and react against trends in modernism, rejecting some aspect of modernism, while fully developing the conceptual potentiality of the modernist enterprise. In some descriptions post-modernism as a period in art history is completed, whereas in others it is a continuing movement in Contemporary art. In art, the specific traits of modernism which are cited generally consist of: formal purity, medium specificity, art for art's sake, the possibility of authenticity in art, the importance or even possibility of universal truth in art, and the importance of an avant-garde and originality. This last point is one of particular controversy in art, where many institutions argue that being visionary, forward-looking, cutting edge, and progressive are crucial to the mission of art in the present, and that postmodern art therefore represents a contradiction of the value of art of our times.
One compact definition of postmodernism is that it rejects modernism's grand narratives of artistic direction, eradicates the boundaries between high and low forms of art, disrupts the genre and its conventions with collision, collage, pastiche, and fragmentation. Postmodern art comes from the viewpoint that all stances are unstable and insincere, and therefore irony, parody, and humor are the only positions which cannot be overturned by critique or later events.