In the book The Culture of Narcissism, Christopher Lasch speculates that modernism and post-modernism grew out of the industrial age as a result of fine art being accessible to common people. That is, as soon as the peasants had access to easily produced ornamentation, the elite no longer stood apart and had to come up with some bullshit to separate themselves by rejecting certain values in art and science such as excellence, precision, craftsmanship, usefulness etc.
Anyway, it's a good book and there are many others, usually dealing with the damage done to science such as Fashionable Nonsense by Alan Sokal.
It seems kind of dumb to name a movement "postmodernism". I mean, it was kind of dumb to have "modernism" in the first place. So you have "modernism" and "postmodernism", what comes next? The naming trend is unsustainable!
-Carefully taking sips from the Fire Hose of Knowledge