Swimmer963:

I wouldn’t describe many of them [my non-believer friends] as rationalists, particularly, but it seems that according to lesswrong doctrine, they are above the sanity waterline while my first friend group is below.

Am I the only one who thinks that this "sanity waterline" model is wildly inaccurate? The model assumes that false beliefs can be somehow ordered by the level of insanity, so that people who have achieved a given level of sanity are immunized against everything below that. This, however, seems to me completely remote from reality. Even if we can agree on some standardized "insanity ranking" for false beliefs -- already an unrealistic assumption -- there's no way people's actual sets of beliefs will conform to the "waterline" rule according to this ranking, not even as the roughest first approximation.

One essential reason for this is the signaling role of beliefs. When it comes to issues that don't have significant instrumental implications, people are drawn to beliefs with the highest signaling value rather than accuracy. High-status beliefs can be anywhere from completely correct to downright crazy, and outside of strictly technical topics, there is typically nothing that would systematically push them towards the former. And indeed, in practice we usually see people with an eclectic mix of correct and ridiculously false beliefs (and everything in-between), with nothing resembling a systematic "sanity waterline."