I was answering an email question the other day that someone had about postmodernism. It's an interesting thing, this philosophical (and now cultural) movement of postmodernism. It's really just a pendulum swing away from what everyone thought in the early 1900's (a philosophical movement interestingly enough called "modernism").
Modernism is essentially scientific positivism. It had to do with the idea that advances in science and technology would eventually cure all of the world's ills. We would become advanced enough to the point that pain and suffering would no longer be a problem, and evil and sin would be overcome, just because we'd have enough knowledge to make it happen.
Well, sometime in the mid-1900's, people began to realize that was hogwash. And that makes sense from the Christian worldview: man is both brilliant and despicable. It's in our nature. We're made in the image of God, tarnished by sin. And that's what we are, so how could knowledge and science and technology erase that?
A quick tangent from my already worn-out tangent on modernism (remember the topic of this post is supposed to be postmodernism). The Christian worldview is really the only worldview that makes perfect sense out of what has been called for ages "the enigma of man." Many people (philosophers, writers, etc) down through the ages have wondered whether man was inherently good or evil, and there were brilliant people in both camps. I think Jung was one of the bigger names in this struggle: he considered man to be "an enigma to himself." But the Christian worldview really hits the nail on the head, that we are both made in the image of God and have made unto ourselves a sin nature.
Anyway, postmodernism was in part the violent reaction to the failure of modernism. In postmodernism, nothing is for sure. You can't know truth, you can't prove anything, you can't even know what I'm saying (because my true intent to tell you things may get lost in translation). This got extended into two major cultural ideas: (1) there is no absolute truth, so whatever you want to believe is fine; I'll stick with my own beliefs, and (2) there is no absolute morality, so go with whatever "feels" good, and if you do something nice and self-sacrificial for someone else, it's just because it makes you feel good inside to do something nice.
Ugh. OK, the first point is obviously false when you think about it. If there is no absolute truth, then the statement "there is no absolute truth" is in and of itself, not absolutely true. It's self-contradictory. As a "scientist" (if I may call myself that), that statement makes no sense at all. If there were no absolute truth, what's the point of empirical investigation (which is what science is)?
The second point (moral relativism) is a bit trickier. I think it's one of the biggest challenges facing Christianity today (that and the problem of evil). First of all, I don't believe it's true. I think it's clear there are absolute moral imperatives. I also think that if everyone was straight with themselves, they also would realize it's true. I don't think anyone can really go about their lives as if moral absolutes didn't exist. We all inherently and subconsciously act as if they did exist. The problem for atheists and agnostics is, if moral absolutes do exist, then where do they come from? More on this later.