It is tragic that thousands of people die each year in car crashes. At the same time, there are huge (if dispersed) benefits to a 70 mph speed limit over a 10 mph limit: a transportation sector that can deliver goods quickly across the country; increased productivity, because millions of commuters can spend more time at work than in transit; and more time at home with our children.

Likewise, thousands of people die in homicides in the United States every year. We could reduce this number substantially, but we have (at least implicitly) decided that the costs — financial and otherwise — of more intrusive monitoring, additional policing, stricter sentencing and other, harsher measures are not worth the benefit. (Though we should continue debating whether marginally higher costs are worth marginally fewer deaths.) A sentry on every street corner and a government-monitored camera in every private room and hallway in America would significantly lower the homicide rate. But I wouldn’t make that trade-off.

How do policymakers decide such things? In the deepest sense, every human life is inestimably valuable. But in a fallen world where trade-offs are inevitable, public policy can’t treat each life that way.