Counter-counter-proposal. There is truth, but no single epistemology is both complete and consistent; therefore, you must employ multiple epistemologies to understand the world, and will fail in some edge cases because the epistemology or interpretation you need hadn't been invented yet (or more mundanely, you made a mistake in your analysis). You can have multiple truths that seem to contradict each other, but are actually from different epistemologies and so can't be meaningfully compared.
Truth is difficult but we can't give up on it. We can't just say, truth is a narrative and all narratives are equal. Or even, some narratives are anointed by consensus. It is not consensus that makes the Earth orbit the Sun. When we reduce truth in this way, we invite the bullshit you described elsewhere.
Another way to think about it is, "truth is a narrative" is a complete epistemology riddled with inconsistencies. There may be some times when it's appropriate; if you're an anthropologist trying to understand different cultures with very different ideas to your own, it may be a very useful frame of thinking to just accept, at least provisionally, whatever it is that the people you meet think. Sometimes we can just let different ideas be in tension and we don't need to come to a consensus. But sometimes we do.
Of course there is no free lunch and this "system of epistemologies" strategy I propose is N epistemologies in a trench coat. It is itself an epistemology, and we're trading completeness for correctness by adopting multiple, contradictory epistemologies and using judgement to decide between them. C'est la vie.
To give a concrete example of what I mean: when I'm wondering what will happen if I throw something, I think in terms of Newtonian physics; when I'm wondering what will happen if I mix chemicals together, I'm using chemistry/quantum physics; when I'm wondering whether I should make a comment on HN, I use an ad-hoc vibes based epistemology based on my experience on HN; when I'm wondering what the nature of reality and the human condition is, I have a similarly ad-hoc spirituality I've developed.
I want to be very clear about something that is easy to mistake in what I wrote. I am not endorsing a principle that "all truths are just narratives and we should give up on the idea that some things are objectively correct or not." Rather, I am speculating that the neurological ability to reason about truth is an emergent property of a system which evolved to do something very different, namely to reason about what other people believe irrespective of if it ultimately matches anything you consider to be true.
Once you start reasoning about the fact that its possible for another person to have a slightly different set of facts in their head, you inevitably take the recursive leap of understanding that the version of their mind you imagine has an imagined version of you and so on. Thus we obtain an understanding of others and their actions built upon evaluating nested scopes to as far as we can think. You can say that the top most layer of the stack is in some way privileged, that it is the reality and is treated special in some way. But why add any special exceptions to the rules when you can just evaluate reality as if it were any other narrative scope?
Again, this is all just a guess of how consciousness is implemented. It is expressly NOT a statement about truth literally being up for referendum.
Assuming such an emergent phenomena is possible, it may be the case that artificial NN can learn to replicate truth semantics without there ever being a clear indicator between "made up story output" and "actually knows what this means" output. In contradiction to the OP, despite there being truth, there may not be a "true understanding neuron". A system of not-bullshit may in fact be built on a system of bullshit.
Truth is difficult but we can't give up on it. We can't just say, truth is a narrative and all narratives are equal. Or even, some narratives are anointed by consensus. It is not consensus that makes the Earth orbit the Sun. When we reduce truth in this way, we invite the bullshit you described elsewhere.
Another way to think about it is, "truth is a narrative" is a complete epistemology riddled with inconsistencies. There may be some times when it's appropriate; if you're an anthropologist trying to understand different cultures with very different ideas to your own, it may be a very useful frame of thinking to just accept, at least provisionally, whatever it is that the people you meet think. Sometimes we can just let different ideas be in tension and we don't need to come to a consensus. But sometimes we do.
Of course there is no free lunch and this "system of epistemologies" strategy I propose is N epistemologies in a trench coat. It is itself an epistemology, and we're trading completeness for correctness by adopting multiple, contradictory epistemologies and using judgement to decide between them. C'est la vie.
To give a concrete example of what I mean: when I'm wondering what will happen if I throw something, I think in terms of Newtonian physics; when I'm wondering what will happen if I mix chemicals together, I'm using chemistry/quantum physics; when I'm wondering whether I should make a comment on HN, I use an ad-hoc vibes based epistemology based on my experience on HN; when I'm wondering what the nature of reality and the human condition is, I have a similarly ad-hoc spirituality I've developed.