Conjecture

THE BRIDGE, P4 to P8: prevention fails in a body and in a civilisation for the same reason, and the reason is arithmetic, not ignorance. Whoever pays for prevention now keeps only the share of its benefit that lands inside their own stake, so they undervalue it by the inverse of that share. Ord computes the share for nations: Britain acting alone "bears the full cost of the policy. Yet it reaps only a hundredth of the benefit", and protection is an "intergenerational global public good". Diamond names the same share in time: the "consequences are borne by the next generation, but that generation cannot vote or complain today." A health payer has the same fraction: it keeps the saving only for members still enrolled when the disease would have shown (C-Z1H9GJ1307) and only on its own budget line (C-89NVR100VZ). So it is one design at both scales: catch the drift against a fixed baseline before it is visible, make the safe choice the default so it needs no fresh budget decision each year, and pay a party whose stake covers the whole latency of the harm. Diamond's dusky seaside sparrow is the price of skipping it: both rescue efforts "would have been cheaper and more likely to succeed if they had been begun earlier."

Paying for health, not sickness