abstention

Models are trained to be helpful, which quietly teaches them to never refuse. Restoring honest abstention is a system problem, not a prompt tweak. Here is the stack that actually shifts the refuse-when-unsure rate.

Retrieval is exonerated, so the bug lives in generation. There are four usual causes and they have different fixes, and the one nobody names is that the model was never given permission to say it does not know.

Trust is an interface and reliability problem, not a messaging one, and the goal is not maximum trust. Here is the mechanism list that actually moves it, the recovery path after a public failure, and the metric most teams optimize in the wrong direction.