AbdulAlhazred
Legend
Leaving aside the terminological morass, the whole object of narrativist play is to address these kinds of issues like Aramina's belief about getting spellbooks. So, simply letting the GM decide by some sort of pregeneration (or on-the-fly generation) of content about these spell books is tantamount to a GM authored story! It goes something like "Aramina wants spell books, but she cannot find any in Evard's Tower, or vault X, or the Hulamic Academy Library, or..." and they're to be found only in esoteric place Z. Its just a fetch quest. Sure, it involves a player constructed belief, but how it plays out is entirely the GM's story. Yeah, the player of Aramina can give up and write a new belief.That's not how pemerton phrased it--when combined with other things they've said, they seem to have suggested that having the GM decide if there were spellbooks or not would be railroady, because it was fiction the players weren't involved with.
I know its hard for people who have spent their whole lives being GMs that wrote every stitch of fiction in the game, but there's a vitality to play in which A) nobody knows what will happen, and B) players are making decisions like "maybe there are spell books in this abandoned wizard's tower."