Rationality requires intelligence, and the kind of intelligence that we use (for communication, progress, FAI, etc.) runs on language.
It seems that the place we should start is optimizing language for intelligence and rationality. One of SIAI's proposals includes using Lojban to interface between humans and an FAI. And of course, I should hope the programming language used to build a FAI would be "rational". But it would seem to me that the human-generated priors, correct epistemic rationality, decision theory, metaethics, etc. all depend on using a language that sufficiently rigorously maps to our territory.
Are "naturally evolved" languages such as English sufficient, with EY-style taboos and neologisms? Or are they sick to the core?
Please forgive and point me towards previous discussion or sequences about this topic.
I don't propose a widely-used language, only a highly specialized one created to work on FAI, and/or dissolving "philosophical" issues, essentially.
As far as I see, the closest thing to what you propose is mathematical notation (and other sorts of formal scientific notation). Sure, if you can figure out a more useful and convenient notation for some concrete problem, more power to you. However, at least judging by the historical experience, to do that you need some novel insight that motivates the introduction of new notation. Doing things the opposite way, i.e. trying to purify and improve your language in some general way hoping that this will open or at least facilitate new insight, is unlikely to lead you anywhere.