Economists and policymakers are on a quest. They are looking for the elixir that will protect their economies from financial crises. Their strategy is to find an indicator that provides an early warning of collapse, and then respond with preventative measures.

We think the approach of waiting for warnings is seriously flawed. The necessary information may never be in our grasp. And even if it were, our ability to respond rapidly and effectively is far from clear. Rather than treating the symptoms of illness after they start to develop, we believe the better strategy is early immunization: the more resilient the financial system, the less reliance we will have on faulty or nonexistent warnings...