Quick Response to Ann
I think the simplest way to think about this connection is "what if Kuhn's notion of paradigms within scientific communities (which he claims make them live in a completely different world) were true about other things as well?"
I can understand that but why? Is that what Kuhn says? Does he apply his notion of paradigms to other things? How did we make that leap?
I think the way they made the leap was just by examining the consequences of if Kuhn's theory was right. If scientists live in completely different worlds than those who lived through other paradigms (presumably because the way they understand the world would be different), then it's not that much of a leap to think "hey, if groups of scientists can basically live in different worlds just based on having different understandings of science, then things like cultures and societies must live in totally different worlds too". And to some extent, this makes some sense. Just look at the vast differences between cultures in areas like morality, religion, or customs. I'm no relativist, but I can sort of see how they make the leap with Kuhn's theory of paradigms.
After reading the postscript to Kuhn's book, I am under the impression that he is only referring his notion of paradigms to all of the scientific community which includes the physics community (Kuhn leads me to assume the physics community is uniquely seperate from the scientific community). Kuhn states (p.180) a paradigm governs not a subject matter but rather a group of practitioners. I am under the impression from reading the text that he is only referring to groups operating in a scientific specialty.