Although we typically apply "postmodern" as a negative term to things like confusing music videos and disconcerting performance art, the idea becomes more useful to us if we can begin to understand it as the breakdown of history under the weight of technology and capitalism. Very briefly and roughly, postmodernism involves three key assumptions:
The rise of postmodernism -- the movement toward space and away from history -- has been tied to a number of forces, including quantum mechanics and relativity, the evolution of capitalism, the rise of information as a commodity, and mass media.
- a loss of faith in "grand narratives",
- the abandonment of foundationalism,
- a fragmentation of stable, unitary identities.
I'm not going to try to pinpoint the cause right now (I don't think there is a single cause; the breakdown of the idea of simple cause-and-effect is another casuality of postmodernism), but we can associate postmodernism's current form with contemporary mangement techniques that value interdisciplinary teams, collapse of middle-management, rapidly shifting careers, and a general movement toward quick change and instability.