We live in a world that is increasingly dependent on elaborate networks: electricity grids, air traffic control, international finance, just-in-time delivery, globally dispersed manufacturing, and so forth. Unless these networks are highly resilient, their benefits could be outweighed by catastrophic (albeit rare) breakdown—real-world analogues of what happened to the financial system in 2008. Our cities would be paralysed without electricity. Supermarket shelves would be empty within days if supply chains were disrupted. Air travel can spread a pandemic worldwide within days. And social media can spread panic and rumour at the speed of light.
It is imperative to guard against the downsides of such an interconnected world. Plainly this requires international collaboration. For instance, whether or not a pandemic becomes global may hinge on how quickly a Vietnamese poultry farmer can report a strange sickness among his animals. And the magnitude of the societal breakdown from pandemics would be far higher than in earlier centuries. English villages in the 14th century continued to function even when the Black Death almost halved their populations. In contrast, our social framework would be vulnerable to breakdown as soon as hospitals overflowed and health services were overwhelmed—which could occur when the fatality rate was still a fraction of 1 per cent. And the human cost would be worst in the megacities of the developing world.