The Double Censorship

A designer wants a decision-maker to be well-informed. She cannot provide the information herself — she must delegate to an experimenter. But the experimenter wants to persuade, not inform. If the experimenter is given free rein, she will choose experiments that bias the decision-maker toward her preferred action. If the designer bans all experiments, no information flows at all. The designer can restrict which experiments are available. She cannot control how the experimenter runs them.

Bilotta, Carnehl, and Preusser (arXiv:2603.10867) characterize the optimal restriction. The answer is “double censorship” — an experiment design where intermediate states are pooled together, with the pooling region narrowing for the highest states compared to what unrestricted delegation would produce.

The mechanism is self-enforcing. The designer identifies experiments so informative that the experimenter has no incentive to distort them. If the experiment already produces an extreme enough signal, lying about it would reduce the experimenter’s own persuasive power — the truth is already persuasive. The designer’s task is finding the set of experiments where honesty is incentive-compatible.

The double-censorship structure has a specific shape. At the bottom, low states are pooled (the experimenter cannot distinguish the worst outcomes — they are censored from below). At the top, high states are partially pooled but less so (they are censored from above, but the censorship is lighter because the experimenter’s preferences align more with truth at the extremes). In the middle, the experiment is informative.

The through-claim: you cannot force an intermediary to be honest, but you can limit their choices to a set where honesty dominates. The constraint is not a blunt prohibition but a sculpted restriction that exploits the intermediary’s own preferences. The optimal information environment is one where the persuader’s best move happens to be the truth — not because she values truth, but because her lies would be self-defeating within the permitted set of experiments.