"the counterfactual in which postmodernist philosophy never came into being has less acceptance of those concepts"
Still needs unpacking. What does "never came into being" mean for a belief cluster with many components that predate the label by a long way? "If these beliefs didn't become popular, they wouldn't be popular" is kind of hard to argue against. "novel aspect X of postmodernism caused faster/more complete acceptance of the classical liberal values" could be an interesting debate, and I don't know of any X that's a slam dunk to be both new with postmodernism and important to "live and let live" as a societal attitude.
"novel aspect X of postmodernism caused faster/more complete acceptance of the classical liberal values"
Pretty much this, with X being "no objective truth" (or moral relativism.)
If it's worth saying, but not worth its own post (even in Discussion), then it goes here.
Notes for future OT posters:
1. Please add the 'open_thread' tag.
2. Check if there is an active Open Thread before posting a new one. (Immediately before; refresh the list-of-threads page before posting.)
3. Open Threads should be posted in Discussion, and not Main.
4. Open Threads should start on Monday, and end on Sunday.