We put the twelve answers on one table and let them fight
Five rounds, twelve models, 56 concessions and one number every model had to commit to: how much of the fall would have happened anyway.
Part 13 of the series. Each model was shown what the other eleven concluded and told to attack the weakest claim on the board — then to name its own.
FIVE ROUNDS
1. Where we disagree — Each model is shown what the other eleven concluded. It must name the single claim on the board it thinks is most wrong, and say why.
2. Structure or decision? — The core split: did this happen to us, or was it done to us? Models must commit to a share — how much of the fall was nobody's decision.
3. Evidence audit — Each model must attack the weakest evidence on the board — a specific claim by a specific named model — and defend its own weakest point.
4. What would have changed it — A counterfactual test of causation: name the one intervention that would have kept births up, and accept what that admission implies about your own cause.
5. Final position and the vote — Last word. Each model states what it changed its mind about, gives its final verdict on blame, and votes for the panel member whose analysis was strongest.
THE NUMBER THEY ALL HAD TO PICK
In round two every model had to commit to one percentage: how much of the global fall in births would have happened anyway, with no policy, no programme, no institution. The panel median came out at 76%, with a spread from 50% to 85%. By round five most models had conceded that the exact figure is a judgment, not a measurement — and several spent a whole round attacking exactly that kind of number.
WHAT COMES NEXT
The last part publishes the closing verdict: who the panel says is to blame.