Postmodernism is actually based around the theory that all knowledge and truths are subjective, and that there are no absolutes. Under this theory, all ideologies are inherently biased, and therefore there is no one ideology that is worth following. Also, there are no originals that are more valuable than subsequent copies. Instead, there is an a anarchic collective of homogenous equals. In accordance with this, adherents of the postmodernist movement borrow from many different artistic philosophies to produce a product that is not original, but that is presented in an original way. In essence, so what if your radical ideas have already occured to others? Originality is over-rated.