I laugh because I have to assume you're only pretending not to know what I'm talking about.
I don't really. I mean, I could try and state it in a way that I think makes sense, but that can be a fair bit of work, and I mightn't get things right.
I keep trying to talk about processes of play - things that people who are sitting around a table, playing a game together, do and say. I get confused when you and others think that we can obtain information about those things by focusing on what happens in the fiction. And vice versa.
The two are completely independent. From how the fiction is established at the table - via the processes of play -
nothing follows about what is happening in the fiction.
Here's an example:
Suppose that the GM decides to describe Thurgon finding some letters from the child Xanthippe to Evard, because (i) Thurgon's player failed a check, and (ii) the rules of the game tell the GM that, in such circumstances, they are required to describe something happening which is contrary to the intention that Thurgon's player had in declaring Thurgon's action. In this situation, it is
true that decisions made by Thurgon's player (ie to declare an action for Thurgon with a certain intent) and certain actions performed by Thurgon's player (rolling the dice and getting a fail result) cause the GM to describe the fictional event. But it is
false to say that, in the fiction, Thurgon looking for some spellbooks caused letters from Xanthippe to Evard exist. In the fiction - as I would have thought is obvious - the letters, written by Thurgon's mother when she was a child, came into being before Thurgon was even born, and he played no role in causing them to exist.
Upthread,
@CreamCloud0 appeared to assert that it is axiomatic that if things done by me, Thurgon's player, at the table cause the GM to establish certain fiction about (say) letters, then it
must be that in the fiction Thurgon caused those letters to exist.
But in fact that is not axiomatic at all, and is in my view obviously false.
Here's an example from AD&D: at 10th level, the AD&D ranger is able to attract followers. Let's suppose that one of those followers is a 3rd level Dwarven fighter. In this case, the player of the 10th level ranger declaring
I've reached 10th level - what sort of followers do I attract? causes the GM to roll on the followers table, and tell the player about the Dwarf who comes to serve with the ranger. It is now obviously true that, in the fiction, this Dwarf was born, learned to fight, and problem did various things to reach 3rd level. The only reason the GM is making all of this part of the fiction is because the ranger's player caused the GM to do so. But no one supposes, therefore, that in the fiction the ranger caused the Dwarf to be born, to learn to fight, to reach 3rd level, etc.
The difference between the AD&D situation I've just described, and a Burning Wheel Circles check, is simply that in BW every player's character has a Circles score, and can declare an action to look out for someone they know, at any time it makes sense in the fiction. And success in meeting such people is gated behind a dice roll rather than an auto-ability that can only be used once, upon gaining 10th level.
The difference between a Circles check, and rolling to find spellbooks, is simply that the former deals with the topic of "finding people you know" and the latter deals with the topic of
finding spellbooks. But the process is the same.
It's
true that BW uses the technique I've described in relation to 10th level AD&D rangers far more often during the game, and for many more purposes. But this greater use of the technique doesn't change it's structure. It doesn't make it true that it is the PC who is causing the people to exist, the spellbooks to exist, etc; any more than a 10th level ranger in AD&D causes 3rd level Dwarven fighters to exist.