[DanielBMarkham]

The universe, fortunately, has a plethora of similarities, such that some basic edge detection and a bit of neural net work in the retinal layers, combined with a bit of proprioception correlation, provides an enormous amount of 90%+ confidence-level shared realities, or at least a good enough fake. Just not 100%. GANS are doing a great job of showing us that not even all of that is required to begin the "faking-out" process.

But the illusion here is the same: that given this natural input we begin processing before birth, that these concepts extend to completely invented terms. Most folks never look there, they never wonder why a car is called a car, and there's no downside at all. It's a pernicious concept and a wickedly-difficult thing to eventually realize.

I don't see where we disagree. The only thing I'd add is that whether you have a completely private language or not, in terms of problem-solving/goal-seeking, is not important. For non-formal, non-tech things, using common words and gestures provides the quickest way forward. Once you start creating a self-consistent system of symbols representing state and behavior, though, you might actually be better off if everybody has completely different private languages. The illusion of common understanding where there is none is more dangerous than misunderstanding. There are no red lights or sirens that go off when human communication failures happen. It's all silence. It could be no other way.