It’s easy to feel as if safety has a universal definition. Freedom from want, freedom from fear—aren’t those what everyone means when they think of safety? Perhaps, but the routes through the world to that state of being are circuitous and varied. Smoke alarms, for instance, have been required in every American bedroom since 1993. We rarely think about them, except to grouse when they go off while we’re cooking. France, however, only began requiring residential smoke alarms in 2015. Switzerland, rated the safest country in the world in 2015 by one consumer-research firm, has not mandated them at all. There is not a simple, one-way progression from a state of nature to a state of safety. Even within nations, there are fundamental divisions about how we want to deal with risk.