Stewart Brand should need no introduction: Whole Earth Catalog, and a personal favourite: How Buildings Learn.
Edge mag invited a whole bunch of folks to say what they changed their mind about in 2007. Guess what our Stewart came out with? Good Old Stuff Sucks. The obligatory quote:
"The Precautionary Principle tells me I should worry about everything new because it might have hidden dangers. The handwringers should worry more about the old stuff. It's mostly crap."