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.
There are Australian Aboriginal languages that work a lot like this, and in some ways go further. The equivalent of the sentence "Big is coming" would be perfectly grammatical in Dyirbal, with the big thing(s) to be determined through the surrounding context. In some other languages, there's little or no distinction between adjectives and verbs, so the English "this car is pink" would be translated to something more like "this car pinks"
Basically what I'm saying is that a large number of the more obvious "extra-radical possibilities" are already implemented in existing languages, albeit not in the overstudied languages of Europe.
By the way, in that word language, I simply have a group of 4 grammatical particles, each referring to 1 of the 4 set operations (union, intersection, complement, and symmetric difference). That simplifies a few of the systems that we find in English or whatever. For example, we don't find intersection only in the relationship between a noun and an adjective; we also find it in a bunch of other places. Here's a list of a bunch of examples of where we see one of the set operations in English: