Why we worry about the things we shouldn't...and ignore the things we should.

At the same time, 20% of all adults still smoke; nearly 20% of drivers and more than 30% of backseat passengers don't use seat belts; two-thirds of us are overweight or obese. We dash across the street against the light and build our homes in hurricane-prone areas--and when they're demolished by a storm, we rebuild in the same spot. Sensible calculation of real-world risks is a multidimensional math problem that sometimes seems entirely beyond us. And while it may be true that it's something we'll never do exceptionally well, it's almost certainly something we can learn to do better.