more on modernism and postmodernism

I've been thinking more about the question that Fred Peatross asked the other day. (I had given a first response to this a couple of days ago.) If I were to hazard a more philosophical analysis of the genesis of full-bore pomo, I would suggest it's the inevitable epistemological implosion that results when man is made the starting point of all knowledge. i.e. when Descartes suggested that the primary epistemic starting point was "I think, therefore I am," he set forth what seems to be an inadequate starting place: Man. Man's mind would appear to be an inadequate philosophical starting place for knowing ab eternalities. If my thinking is correct here, built on this shaky foundation, the epistemological collapse down to skepticism and postmodernism was perhaps inevitable (where "Man can know everything" segues to "Man can know nothing" - and please understand I'm painting with a broad brush here). I suggest modernism and postmodernism both have their anthropocentric epistemological luggage. Comments? I'd especially like to hear from those who have done particular study in this area (professionally or not).