Significant spoilers for mad investor chaos and the woman of asmodeus (Book 1).
Dath ilan has put significant effort into protecting what it has to protect. To that end, it's thought quite a bit about how to think effectively. Dath ilan knows how to train people to preempt reality, to concentrate their thoughts on modeling the tiny slivers of possibility space that reality is on track to wander into and to effectively respond.
However, they don't disseminate this art to all their citizens to the greatest possible extent. They teach it fully to just a select few, and teach everyone else a good chunk. Their reason for holding out on making most people into the best rationalists they can be … is that, as an unfortunate quirk of human psychology … becoming the best rationalist you can as quickly as you can is not the most fun path you can chart through your life.
A few dath ilani specialize in becoming Keepers -- full time, professional, regularly tested and proven masters of Bayescraft. Keepers in dath ilan are the "adults in the room." Their job is to make sure that everyone else can life a fun-theoretically optimized life without sacrificing their civilization's ability to seriously reason about its future. A purely Keeper civilization would be missing out on something worth protecting; a civilization without enough adults around would be helpless in the face of capricious reality.
There is a commonly held wisdom, in dath ilan, about the way a human mind is put together, that it is a thing made of little subtle tensions and balances and internal compromises. The human mind being the limited thing that it is, these balances form around your current level of ability to see into yourself and see the implications of what you already know - or not see them, as the case may be. The reason why not everybody runs off to learn all they can from Keepers, the reason why not everyone asks a Keeper to tell them all the answers about themselves, is that this would bring parts of themselves into conflict that were previously living in a more agreeable truce of ignorance. You might not survive as yourself, if you could see yourself.
Those who say "That which can be destroyed by the truth should be" may continue to walk the Path from there. But not uncommonly, even somebody who sets out along that Path, turns back at some point, and well short of becoming a Keeper. It's not a trivial price, higher for some than others, and there is varying willingness to pay. A lot of the reason why Keepers exist as what they are, is that the people who have large comparative advantages there - in how little they'll be hurt by knowing themselves, or how much they really internally want to keep going anyways - are conceived of by larger society as being paid to throw themselves on that grenade, so others don't have to. And if, to some Keepers, it doesn't feel like much of a grenade at all, they understand that their case is not typical, and are grateful for winning the comparative-advantage lottery.
Going up by two local standard deviations, in whatever it is that Owl's Wisdom enhances, is something that the current structures of Keltham's personality were never built to withstand. He knows, from up here, because he couldn't stop himself from glancing in that direction, that in dath ilan he would never have had his 144 children. He would have tried to be special and failed and been sad and then maybe gotten an ordinary +0.8sd job and either paid for a child out of that or decided he was too strange and unhappy to have one.
It's not considered necessary for somebody Keltham's age to go and pay a Keeper to tell them exactly what the probabilities are, about something like that. It's not so much that people are encouraged to lie to themselves, reality forbid, but that people are told it's okay for them not to shove themselves as hard as possible down the Pathway that will dissolve the mistakes their current personality is built out of. That's what Keepers are for. They do it so that not everybody else has to. There are grownups around in Civilization, who can and will speak up if the people less mature are about to make some terrible mistake out of their blindness. So you do not need to rush ahead to be a Keeper if you'd rather be a little less coherent, a little more yourself and your mistakes and your contradictions, a little more human, for a time.
But it's too late now, for Keltham to go back, because also in the common wisdom is that once you see what it is you weren't letting yourself see - once you know which mistakes your personality is founded upon - or even if you're trying hard not to know it, to the point where it's becoming a big internal battle - well, at that point, you're supposed to give it up. It means that, well, sorry, you are that smart now, like it or not, you are that wise, you did grow up that much whether or not you wished to stay a child for longer; it's time to move on.
Dath ilani think of Keepers the way children in our world think of adults, or the way our ordinary adult citizens think of agents of the national security establishment. When something actually scary occurs, there exist people who are competent to take charge and do something. They don't have to be adored, but they are respected. When things are serious, people's eyes turn to these maximally competent authority figures.
Our world faces a dire, actually serious problem. We're children playing around the unexploded bomb that landed in the playground. Some of our eyes turn to the place where the authority figure would be … and there's no one there. We're all children.
So our world needs to generate adults in the room, and fast:
To my memory, I have always been reflective. But I have witnessed the growth of others, and in at least one case I've taken someone across that Rubicon. The one now possesses a more complex and layered personality - seems more to me now like a real person, even - but also a greater emotional distance. Life's lows have been smoothed out, but also the highs. That's a sad tradeoff and I wish it didn't exist.
I don't want to have to choose between sanity and passion. I don't want to smooth out life's highs or even life's lows, if those highs and lows make sense. I wish to feel the emotion appropriate to the event. If death is horrible then I should fight death, not fight my own grief.
But if I am forced to choose, I will choose stability and deliberation, for the sake of what I protect. And my personality does reflect that. What you are willing to trade off, will sometimes get traded away - a dire warning in full generality.
In the possible worlds that make it, enough good people make that tradeoff, and come to embody what they must to carry the weight of the rest of us. Some tradeoffs are clearly worth making.