If I recall, addressing this was part of James' Pragmatism already. Take for example determinism vs. free will (which IIRC was an example James focused on) - they're clearly incompatible, but that incompatibility can't "manifest" appropriately so in some sense it's not compelling. A pluralist-but-not-nihilist may then take the stance that while there are incompatible but equally acceptable accounts of some subject matter, there are no equally acceptable accounts which are pragmatically incompatible. But it's been a long time since I read the book, so I could be misremembering wildly.

An excellent point. But that there are "no equally acceptable accounts which are pragmatically incompatible." is an empirical question. And pragmatism begs the question "works for what," or toward what end?

First, there is a long way from having more than one "definite code" to anything goes, especially if the codes are designed to serve different purposes. Second, just because more than one will do, even for the same purpose, does not mean that any one will do, or that all will do equally well. The lesson of pragmatism is that "the truth" is always dependent on which end it is for, and whose, but in many contexts the ends and standards are widely shared, and the number of incompatible options that pass the shared tests of coherence, plausibility, unification, parsimony, etc., is very limited.

As always, @Conifold, your analysis is literally impeccable. However, you have surely have noted over the years of commenting upon the many queries that I've posted in this "vein," that my concern is not pedantic, but how the cultural ethos, folk epistemology, the ideal of democracy itself, is to accommodate the evolution/conclusions of late 20th C academic epistemology. Have another look at that brilliant article you recommended to me surveying various justifications of the "slippery slope" notion. What happens if radical skepticism becomes the norm outside of academia?

Nihilism is the flip side of absolutism. Either we carve the nature at its joints or anything goes, either God himself lays down morality or anything is permitted. It is the rigid all or nothing traditional ideology, that Dostoevsky's quote perfectly embodies, that brought about the existential panic and the farce of post-truth. In the wake of its inevitable collapse. I see pragmatism not as an ill but as a cure, a shot of rational humility and moderation to face off the extremes. If indeed the public absorbed absolutism and post-truth from academics if only we got it to absorb the pragmatism.

I see 'post-truth' thinking as stemming directly from the failure of philosophy.in our society and its lack of epistemic grounding. This would be one of the reasons I get so shirty on philosophy forums, that the low quality and parochialism of university philosophy has such a terrible effect on society.

@Conifold, again, agreed. Truth is not fixed, eternal, absolute, and unchangeable. The issue with pragmatism, however, is that in order for something (an idea, policy, tool, etc.) to "work", to be useful or successful in its practical application, etc., there must exist, goal or purpose, an end, a desiderata. Something pragmatism has has a hard time coping with, notwithstanding Dewey’s attempt to resolve the issue with his argument that the means by which a policy supposedly achieves its end necessarily calls into question the value of the end. Simply broadening the dilemma.

@Conifold And consequentialist utilitarianism, never particularly reliable as a way to constitute such desiderata, becomes increasingly unstable as the notions of pluralism and the inclusion of diversity tout court become free floating ends in themselves: essentially non-truth apt “hinge” concepts, not to be questioned. And, like all hinges, they serve to reintroduce a dose of absolutism into the culture...

Despite the fact that they may tend to perniciously exacerbate the instability of our only remaining compass, consequentialist utilitarianism. And does not the absolute criteria-less acceptance-i.e. anything goes- of pluralism/diversity tend toward nihilism?

Ends and desiderata are there at work as is, although they may not be spelled out. That pragmatism puts them upfront isn't an issue, it is a feature. Their formulation and clarification is part of the process, not unlike building theories in empirical science. Which is why pragmatic ethics isn't utilitarian, with some fixed, and nebulous, "utility". The search for such utility, and stability it promises, is a residue of the longing for moral absolutes, with their false dilemmas.

We are as fallible in understanding our ends as in forging our means, healthy skepticism of their full embrace is a good buffer for the fallout when they misfire, just as scientific theories do at times. Sensitivity to motivated doubt and critical self-correction tout court, that Peirce advocated, are better instruments of maintaining stability than a rigid foundation that wears it on its sleeve, but never delivers. Pluralism and diversity as ends in themselves are as inimical to pragmatism as moral absolutes, so it is well-equipped for checking both absolutism and nihilism alike.

@Conifold By "there at work [while] not spelled out" are you talking mysticism, form of life, or making some kind of transcendental deduction? Pierce's abduction, for instance, starts with [an] observation/s then tries to come up with the simplest most likely/best available explanation for IT (the observation or phenomenon observed). The act oh hypothesizing has a [grammatical] object. A means has an end. What you seem to be talking about is something quite different. BTW I always had trouble with Dewey's means/ends discussion too.)

Simply put, as Hume pointed out, reason will not tell you where to go, but only the best way to get to wherever you want/desire to be. And pragmatism's only handmaid.

@Conifold In a 2017 comment of yours to the question: "What is the argument from tolerance for cultural relativism? Why does it fail?" You say that “Tolerance has to be made into an absolute value over and above cultural differences” Does this mean that you are NOT an absolutist in your abhorrence of absolutism? Maybe in order to avoid the slippery slope of pluralism/cultural relativism/multiculturalism? I realize that I am conflating cultural/moral and conceptual/epistemic and relativism/pluralism. But as Putnam discussed, the boundaries here are fragile and porous.

It is an empirical observation, we find a way to describe what we do as ends directed, and then refine them to "improve" what we do. Why should it be reason? We have emotions and biological drives to "tell" us those things. Stark separations between means and ends, facts and values miss what people call the "dialectic", their mutual feedback, ends and objects we eventually settle on are not there in full platonic glory. The quote is not in my first person, it is what needs to be done to make an inference in the OP suggested argument work, which then makes its premises inconsistent.

@Conifold Again, by "what we do," do you simply mean what we [individually and collectively] happen to find ourselves doing, how we happen to find ourselves [re]acting? Akin to Wittgenstein's "agreement in action" which underlies the phenomenon of language and our forms of life? Then find ways of describing, guided by our biological and emotional drives, that “doing” teleologically (in terms of the purpose it serves rather than causally- say in the way of myth, and/or Darwinism), in such a way that refinement can be described as improvement of “what we do.”

Yes. Peirce advocated the condition we find ourselves in, "with all the prejudices we actually have", as the starting point long before Wittgenstein. And advised to crtitically reflect on this condition, and doubt and question it when there is a positive reason to do so. "Critical common-sensism" as he called it. A major difference between pragmatic ethics and utilitarianism is that ends are not prescribed based on some theory of "human nature". They are part of the ongoing ethical inquiry just as the means of achieving them, fallible and open to revision like everything else.

@Conifold A kind of progressive conservatism. Is your model based exclusively on Pierce (who I agree anticipated much of what Wittgenstein later proposed)? I see a bit of Dewey's thesis in "Reconstruction in Philosophy" as well. Nevertheless, I continue to see a kind of unabridged gap in the reasoning akin to the metaphorical pulling yourself up by your own bootstraps, and which is essentially the genesis of the disagreement between Sam Harris and Jordan Peterson about the notion/nature of [moral] "truth."

@ Conifold Better: conservative progressivism