In general, the probability of death is pretty simple to calculate. It’s 100 percent. We all die.
But the devil is in the details. Humans fear catastrophe and disaster, and accordingly, tend to worry about horrifying events: gunfire, a terrorist attack, lightning strikes. The fact that such grisly ends rarely come to pass—especially if you stay inside during thunderstorms—doesn’t seem to reduce such concerns.
Every year, the U.S. Centers for Disease Control and Prevention publishes a compendium of how many Americans died the year before. There’s plenty to be learned about freak accidents—two people died in 2014 from “ignition or melting of nightwear”—but the data also shows how exceptionally hardy human beings are.
In any given year of their lives, Americans far more likely to keep chugging along than not. Even at the frail age of 85, you have a 92 percent chance of surviving to the next year.
Pretty good odds! But this is where probability comes in. After all, life is not a single roll of the dice, but thousands. Survival is rarely dependent on a single, cataclysmic moment of chance, but years of smaller risks — the 0.089 percent chance of heart disease at age 50, then 0.098 percent at 51, and 0.109 at 52.