Is postmodernism developed enough to be defined?
“Postmodern” is becoming the “Attica” of an entire generation. Rather than a statement about excessive police force, it is the cry of a generation that feels it has been oppressed by the assumptions and worldview of its forebears. The language of postmodernism is ubiquitous, but it’s incredibly difficult to explain what, exactly, it is.

Jacques Derrida, aka Ralph Lauren's sexier older brother - Early don of postmodern thought
One of the major problems is the “Observer Effect” or “Hawthorne Effect”: The act of observing and event or phenomenon changes it. Contemporary Western society has a strong awareness of its intellectual traditions stemming from relatively Eastern roots in Greece. We understand the differences in epistemology and metaphysics that separate classical, medieval, Renaissance, Enlightenment, liberal, and postliberal thinking. We have dissected and explained where and when they started, how they developed, and, more or less, pinpointed where we stand today. As a result of all that study, we are painfully aware of the shift that is occurring, and we are paying it its due attention.
But as observers of the phenomenon of postmodernism, we are changing it’s nature. The philosophical debates of the past seemed to focus on which concepts were right and better; the questions were asked and answered with the purpose of improving human thought and communication. But the conversations on postmodernism seem to be mainly focused on defining “postmodernism”. They are conversations in which you’ll hear the phrase, “That’s not postmodern thinking!” It seems that many people think that postmodernism is something already fully developed (of course it is, it has a name, doesn’t it?), and if they can name it, they can automatically jump to the better life that it promises.
But postmodernism isn’t formed. It isn’t even really an entity. It is simply the indication of the amorphous worldview emerging during the effective death of Modernism. It is the toddling child of Modernity, mobile and active, but undeveloped. My prof, Glenn Kreider best described the true nature of postmodernism: “It is what it is.” Postmodernity is the antechamber of the next Western epistemological tradition.
McGrath is certainly right in asserting that “postmodernism is a vague and ill-defined notion, which perhaps could be described as the general intellectual outlook arising after the collapse of modernism.” (though he goes on to attempt to clear up the vaguery and improve the definition) That lack of clarity is probably the most readily recognizable feature of discussions of postmodernity. We all seem to “know” what it is, but have an impossible time describing it, even to ourselves. In fact, the reality of one of the most consistently acknowledged features of postmodern epistemology – non- or anti-foundationalism – is playing out in the discussions about defining the movement; that is, each person’s ideas about postmodernism are based in different communities, different worldviews, etc., so they can’t communicate (someone call E.D. Hirsch).
Too much time has been spent attempting to describe the particular detailed philosophy that postmodernism will engender, when that is something that we are only changing every time we try to describe it. Even postmodern thinkers seem to be unaware that because of the foundation of postmodernism – that there is no universal foundation of knowledge – that it must necessarily splinter in myriad directions. Though postmodern thinking is typically associated with relativist, progressive, politically liberal positions, in the end the philosophical distinctions of postmodernity will be as diverse as those of modernity.
Postmodernism is the next step in Western social evolution. From our perspective it is all but impossible to define what will finally emerge from the epistemological ooze and survive. Are we looking at the full-blown emergence of Murray Jardine’s “expressive aesthetic individualist” culture? Will Unitarian Universalists win the war of religious tolerance? Will we all get blown up by the only people left in the world who think there is one truth (peace be upon them)? It’s really too soon to tell.
I suspect that we'll see a return to modernism. In fact, I would cite the increasing importance of the New Atheists as an example of the public acceptance of scientific positivism/materialism as the defining cultural epistemology. While most academics I know would reject this movement as untenable after the collapse of Modernity, there seems to be a fairly powerful popular movement in this direction. Because it's primarily popular, it seems to totally ignore past ideas (like postmodernism's powerful critique of modernism).
p.s. I hope I'm wrong.
I hope you’re wrong, too. There’s a lot wrong with Modernism, and I think that once we’ve shed it, Christians throughout the West will wonder how the faith survived the last 350 years. All of that glory goes to God.
I think what we’re seeing with positivism is the lag that is inevitable from movements passing from academic to popular audiences. It’s only been a couple of generations since logical positivism was considered strong, and it will take some time for the rest of society to figure out what Anthony Flew tried to tell everyone decades ago.