In no small part due to Phil Thrift's presentation on the Postmodern philosophy of Iranian mathematician Mohammad Sal Moslehian, I'm becoming more interested in Postmodernism as a genre. I haven't yet studied the genre extensively, but I have a few thoughts going in.
First, I'm confident that 90% of Postmodernist philosophy is crap. Not because I have anything against Postmodernism (quite the contrary), or even because I've read a ton of Postmodernist philosophy (which I haven't), or even that I've done some sort of statistical sampling. I am, however, a firm believer in Sturgeon's Law: 90% of everything is crap. The corollary is of course: "The existence of immense quantities of trash in [Postmodernist philosophy] is admitted and it is regrettable; but it is no more unnatural than the existence of trash anywhere."
It seems fairly obvious to me that in essence, just as Modernism was an attempt to justify the authority of our cultural, social, and philosophical systems, Postmodernism represents a general revolt against every kind of authority. "What're you rebelling against, Johnny?" "Whaddya got?"
Many--perhaps even most--of these rebellions are going to miss the mark. Some due to the incompetence of the attack, a few due to the solidity of the authority itself.
Raised in liberal, individualistic politics, outside of any organized religion, and proudly nurturing a lifelong addiction to science fiction, I'm a Postmodernist in this skeptical and rebellious sense to my very genes. I see most authority simply crumble if even the possibility of skepticism is admitted. And these authorities should crumble. What authority I do acknowledge--the authority of the scientific method, for instance--is not due to any dogmatism, but rather because I can see that these few authorities are strengthened by skeptical challenge.