This post seems to be missing one important thing about Culture universe (unless I missed it): in that universe "high-grade transhumanism", if I understand the term correctly, is possible, and, if anything, common. The Culture is an aberration, one of very few civilization in that universe which is capable of Sublimation, and yet remains in its human form. The only reason for that must be very strong cultural reasons, which are constantly reinforced, because all those who do not agree with them sublimate into incomprehensibility before they can can significantly influence anything.

I now usually simply trust salesperson's choice, after explaining my requirements, only checking that his choice seems to satisfy them, rather than trying to optimize over all the available options. It's probably the main thing salespeople are for in the first place, not to provide expertise (which they often don't have), or even to find the best option for your requirements, but to simplify the choosing process, lifting the psychological weight off the customer.

Robin, if people could always be trusted to say when they themselves could be trusted, the problem would have a very simple solution at the meta-level. So if you're going so far as to ask that question, then people can't trust their choices, or trust themselves to know when to trust their choices, or meta-meta-trust, etc. And this goes for everyone having the conversation. Not going anywhere in particular with this, just making the observation as a starting point.

It seems to me that adult humans, dealing with other adult humans, are very rarely justified in removing the choices of people who haven't chosen to trust them.

But we recognize e.g. parents and children as an exception, where the parents are expected to have a hugely superior epistemic position, to have (brainware-supported) motives to care for the child's best interests, and finally we have large amounts of historical experience with the situation. (It doesn't always work perfectly, but on the whole, it still seems like trusting children to know when to trust their parents would be worse.)

Not that this is a metaphor for anything. It's different out in the transhuman spaces.

If you have lots of entities with root permissions on matter, any of whom has the physical capability to attack any other, then you have entities spending huge amounts of precious negentropy on defense and deterrence.

That is what we have today. Perhaps strangely - if you walk through a tropical rainforest, you don't see that much fighting - it all seems rather peaceful most of the time. Nature really likes cooperation.

If there's no centralized system of property rights in place for selling off the universe to the highest bidder, then you have a race to burn the cosmic commons, and the degeneration of the vast majority of all agents into rapacious hardscrapple frontier replicators.

The frontier folk would be very cool! They would have amazing technology - and would travel near the speed of light. That's a funny sort of "degeneration".

I'm depressed about the coming end of the human race. Got a solution for that? :-)