You are exactly right to say that this is postmodernism. Postmodernism says that all speech is not about truth, but about power. These people believe that.
And they act the way they think. Their speech is all about power, not about truth. That's why their claims are so absurd and nonsensical - because it's not about the truth of the claims. It's about them asserting power over you.
The only reasonable response, then, is to not accept their assertion of power. No. Just no. (Or "no" with as many profane modifiers as you feel is appropriate.) No, we don't agree. No, you're ridiculous. No, we aren't going to get in a debate with your ridiculousness. And most of all, no, we aren't going to follow your stupid rules. No. Get lost. Go away.
Totally with you, but the problem is that the amount of places where "no" is not an option, is growing. Meaning, it's personally risky to go against this narrative in some contexts.
And they act the way they think. Their speech is all about power, not about truth. That's why their claims are so absurd and nonsensical - because it's not about the truth of the claims. It's about them asserting power over you.
The only reasonable response, then, is to not accept their assertion of power. No. Just no. (Or "no" with as many profane modifiers as you feel is appropriate.) No, we don't agree. No, you're ridiculous. No, we aren't going to get in a debate with your ridiculousness. And most of all, no, we aren't going to follow your stupid rules. No. Get lost. Go away.