We're very very very obviously not going to reach any form of consensus here, as I'm arguing from the perspective of practicality and you are arguing from one of philosophical purity (neither incorrect, in their own domains - but often incompatible) - so I'll just pick the most relevant point to hopefully allow you to understand why, and then leave this fruitless conversation alone.

> you are framing the situation as being that attention to accuracy/truthfulness will necessarily yield failure.

No - you've misunderstood or willfully misrepresented the situation. _In general_, attention to accuracy and truthfulness are virtues which increase the likelihood of a successful collaborative enterprise. They become failings when they are excessively applied, beyond the point of helpfulness (which is a different point depending on the domain or topic under discussion). In a discussion about philosophy of mind, questions like "Are my sensory perceptions accurate reflections of the world, or hallucinations? Is it meaningful to make measurements of the world?" are pertinent, and meaningfully affect the successful outcome of the discussion. In a practical discussion about measurement of the fractional-volume of the Universe taken up by humans, they're not - if the answer is "no", the whole of the rest of the discussion is moot, so _in order to allow the conversation to proceed_ to a helpful (albeit admittedly "based on an assumed axiom") conclusion, they are taken to be "yes". The objective of the discussion is not a philosophically bulletproof airtight proof, but a conclusion which is reasonable and helpful.

If you asked a friend to give you directions on how to walk from their house to the corner store, and they answered "I can't tell you that. I only have my own perceptions to go on, and I cannot know that they reflect the world accurately, let alone any experience that you might have"; would that be a useful conclusion to the conversation? Their response would be intellectually and philosophically pure, but practically unhelpful.

If the friend said "well, last time I walked there I went north two blocks and then left on 4th street. I guess that'd work for you" - that's a philosophically weaker statement which could be criticized as inaccurate (_did_ they take that path? How do they know that? Even if they experienced sensations reflecting those statements, how do they know that those statements are true? Even if those sensations were accurate, how do they know their memory is accurate? Or that the streets haven't been reconfigured in the intervening time?), but is still helpful. It's wordier and more complex than just saying "go north 2 blocks then left on 4th", sure - but for someone aiming for philosophical purity _while still being helpful_, it's a reasonable compromise. This added attention to accuracy does not lead to a failure. But the original "I can't tell you. All experience is unknowable and incommunicable" statement _is_ a failure, despite being "more accurate". It is over-application of accuracy beyond the point of helpfulness that leads to failure, not accuracy itself.

Almost all human endeavor is built on a towering edifice of disciplines and abstractions, each relying on the stability and fitness-for-purpose of the layer below. Physics relies on the usefulness of mathematics without reproving its theorems, web application developers make use of the Internet without rewriting network protocols from scratch, athletes carry out team strategies without consciously thinking about each individual muscle activation, legislative bodies organize nations without directly communicating with each individual. _Familiarity_ with the concepts and limitations of the layer(s) below one's area of operation is valuable, to avoid making assumptions that will not hold true at the boundary - but useful outcomes almost always result from assuming that a dependency which has been consistently reliable and accurate will continue to be so. Responding to a question about practical physical measurement with a rebuttal that physical measurement is philosophically impossible is technically-true, but unhelpful.