Okay TakesI often find myself in conversation with people who believe that there is no coherent unique "reality" which all of us perceive and to which we all refer; or that to form consensus about such a reality is impossible.
Interestingly, this is generally defended not on philosophical grounds (on which it's not very defensible), but rather on historical-ethical ones. The idea is that Eurocentric, totalizing theories helped justify and drive imperialism and served as the foundation of imperial ideologies. Therefore, totalizing theories and fixed ontologies are imperialist.
If we are going to advocate relativism on ethical grounds, we have to ask: What is the impact of relativism on the world? If we are going to boil down philosophical claims to their moral import, then perhaps we should subject this approach to its own metric.
With respect to imperialism and neocolonialism, we consult Paul Farmer (well, young, radical Paul Farmer), who works intimately and critically with global systems of development and aid. He points out in Pathologies of Power that moral relativism has been instrumentalized to render acceptable the suffering of nonwhite people. So the anti-imperialist function of relativism seems to have been turned on its head.
Looking at the broader cultural impact of ontological relativism makes it clear that it has failed as a progressive ideological project. The scientific consensus tends to offer a reading of reality conducive to the pursuit of human liberation. It admits that the Armenian, Jewish, and Native American genocides happened; that non-white, trans, and poor people in the US have dramatically worse health outcomes than their wealthy, cis, white counterparts; that there is enough food for everyone to eat and enough houses for everyone to live in.
The most popular, visible, and impactful ways in which people’s versions of reality diverge from this are almost invariably horrifying. Alternative facts like Holocaust denialism; the idea that there is a hell that gay people and everyone who falls within their sphere of influence will go to; Pizzagate — these are the points for divergence from the modern ontological consensus that actually impact the world around us.
Traditional indigenous belief systems, herbal medicines, and the guidance of ancestors are, frankly, comparatively politically irrelevant in the modern US. Yes, we should support cultural rights, and yes, we should oppose capitalist imperialism, which desecrates everything it can turn into a market and forsakes the rest, and yes, we should support the fuck out of indigenous resistance. But the reality of the current political moment is that the alternative ontologies sometimes bundled with left anti-oppression movements hold no political import in the US.
To be a US American leftist advocating for ontological relativism right now he’s like advocating for “states’ rights” while earnestly believing that it’s actually about direct democracy and having a sense of agency in one’s life. It’s simply has nothing to do with present day political reality.
This is not to say that we ought to heed modernist interpretations of reality. Modernism, the regnant philosophical interpretation of capitalism (for its sympathizers) up to the ascendancy of neoliberalism, is defined largely by its optimism. It is the basis of all liberalism. (It is also, it should be noted, the basis of classical statist communism).
Admitting that we are talking about the same world as (most) capitalists and politicians allows us, for one, to excoriate them when they lie about that world. But moreover, it does not restrict the interpretive framework through which we seek to understand the world more broadly. It is these interpretive (not ontological) frameworks that provide a moral evaluation of capitalism, and suggest other possibilities beyond it.