The problem is that a lot of thinkers accused of being postmodernists reject that label. For example, Umberto Eco had come out as a minimal realist. That is one of the more reasonable interpretations of continental thought I know of. I don't think singularitarians could honestly deny that what most people regard as everyday reality is largely a social construction, although there are facts behind it regardless.

As for the less reasonable interpretations, their solutions would depend on 1. their ontology, and 2. their stance on violence. IIRC thinkers in the lineage of Deleuze propose schizophrenic thinking as the answer. I think this is a bad idea, but if you agree with Deleuzians, then we next need to ask what you think of what postmodernists call "violence". If you are a pacifist, then you would refuse to use the notion of truth as a rhetorical device. If you believe in violence, then you would cynically use it to smash your opponent's arguments to smithereens, all the while believing there is no such thing as truth.

The arguably "postmodernist" strategy I personally like the best is an interpretation of Lacanianism I cribbed from Zizek, though it is not strictly faithful to anyone's work in particular. Like most postmodernists, Zizek of course denies that he's a postmodernist and has come out as pro-science. Anyway, he says that struggles within each culture take the form of contending universalities, competing visions of what counts as fair and just for all. Universalities often take the form of equivocations or deadlocks where you present multiple sides of an argument as though you are unable to decide between them.

The problem is that most people would experience an absolute recoil from being equivocal about certain ideologies, such as Stalinism, Nazism or Islamism. But different people have different ideologies they recoil from in this way. In his old posts, Curtis Yarvin expressed sadness that he could not see the progress of Nazi technology, discussed ultranationalist Germans without his hostility towards communists, and so on, even though Yarvin was obviously not a Nazi himself. The YouTuber Contrapoints is playing the same game with Antifa.

Works like these which equivocate between multiple conclusions are perceived as universalities, but the universalities produced by different people are themselves in mutual contention. It is inconceivable for Contrapoints to equivocate with regards to the fascist-leaning right, just as Yarvin would never exonerate the Antifa to this extent. Presenting people with these emotionally authentic equivocations can shift their stances more reliably than straightforward arguments because of the message inscribed into their structure. Thus whenever anyone tries to play just and fair, pay attention to the positions they are excluding from their equivocation as a result of absolute recoil, because that is the true ground where universalities contend with one another.

This ground or backdrop against which universalities contend is the true universal, the Deadlock itself which even purported universalities are unable to escape. Lacanians call this the Real, the obscene truth from which we all flinch away. What is this "truth", and in what sense is it obscene? One who presents such a truth would be equivocal about Stalinism, Nazism and Islamism, his own death and the death of his family and friends in the same way that Contrapoints presents the deadlock between Antifa and her left-liberal position. Such a pose would strike us as comically inhuman and probably psychotic.

Comparing this account with Yudkowsky's presentation of rationality, it is clear to me that these two parties are talking past each other. Zizek is obviously talking about authentic emotional truth, whereas Yudkowsky is talking about factual truth.

Yudkowsky might find Zizek to be observant in some ways. The problem is that Zizek would probably dispute that Yudkowsky has any point whatsoever. He would say that all seeming facts are inscribed within extremely large and complex fields of mutually contending equivocations, all of which suppress the ideas they find intolerable. This is hard to deny since modern science rejects strict logical foundationalism. Traditional foundationalism is not always a good thing either, since it can be used to deny that new work is scientific at all if it contradicts the accepted foundations. Even Yudkowsky admits this in his essays against logic.

The only sanity-preserving solution I can think of is Umberto Eco's minimal realism.