What is Hallucination?
A fluent, confident answer that is not supported by any source. The problem is not that it is wrong. It is that it is indistinguishable from a right answer.
The failure mode that matters in an operation is quieter than the famous examples. It is not an invented citation; it is a real provision, correctly quoted, that governs a different category of case. A system trusting similarity alone will return that confidently, and nobody catches it until the wrong expectation has already been set with somebody.
Which is why the answer is structural rather than a better model. Every answer traceable to an approved source, so a reader can check it in one click; a refinement pass after retrieval that discards candidates on grounds other than similarity; and a system that says it does not know, which is a product decision more than a technical one. On one published-guidance assistant that combination moved same-session task completion from 27% to 68%, with every answer traceable - and the traceability is what ends the objection, not the completion rate.
| On this | Hallucination | A model with a lower hallucination rate |
|---|---|---|
| What is being fixed | Whether a reader can check the answer | How often the answer is wrong |
| Effect on the confident wrong answer | Surfaced, because its source does not support it | Rarer, and still indistinguishable when it happens |
| What it survives | A model change, because the constraint is outside the model | Nothing: the next model has its own rate |
- When it is the right answer
- When a compliance, legal or safety reader asks how they would know the system was wrong. That question has a structural answer or it has none.
- The service line that delivers this
- Semantic Search
Someone asks about retiring early. The system returns something that reads like an answer - and it governs a different category of member entirely. Nobody catches it until the wrong expectation is already set.
Start here
If a term here is the one your board paper turns on, ask us about it.
We will send the entry, the evidence behind it, and the honest note about where it does not apply.
You get a reply within one working day, from the engineer who would do the work - not a sales sequence.