What they were doing is the heart of Modernism, a “movement” in thought that dominated the first half of the twentieth century in Europe and America. It arose in response to a more Victorian notion of the static nature of the universe and to an Einsteinian rejection of that perceived stasis. Many Victorians saw knowledge in counting and categorization. If things could be named, things could be known. And they saw themselves as objective observers, outside of the processes they were observing, unconnected with the things they were describing. Einstein convinced quite a few people that this was wrong, that we live in dynamic situations where even the act of observation alters the observed. Rather than fighting this, the Modernists tried to utilize it–hence, “Make it new.” The Modernists wanted to change the way things are seen and use them in ways they have never been used before.
If Modernism moves concentration from the object to the object/viewer dynamic, then Postmodernism moves it further, stressing the viewer and the act of viewing–making the viewer a creator through that act of viewing. Postmodern art doesn’t attempt to reflect a world “outside” or even relationships with that world. Instead, it tries to represent the strengths and weaknesses–and processes–of perception. The world no longer matters; perception, all we really can “know,” is all, in fact.
From a belief in objective reality the movement was to concern with subjective perceptions of reality. From there, the movement was to concern with perception only. If reality cannot be known in an objective fashion, why deal with it at all? Concentrate on perception, for that (to the Postmodern mind) is really all we have.
[Last night, in a comment on a diary over at The Daily Kos and in an act that might have been the height of hubris, I promised a diary on the difference between Modernism and Postmodernism. Books have been written on the subject, and it is still argued heatedly. And I am no expert. So, don’t take what I have presented here as definitive, simply as one more starting point for the ongoing investigation into art and its movements.]