We all like to throw around terms that describe human behavior — “bystander apathy” and “steep learning curve” and “hard-wired.” Most of the time, they don't actually mean what we think they mean. But don't worry — the experts are getting it wrong, too.

Sure, medical progress has been astounding. But today the U.S. spends more on healthcare than any other country, with so-so outcomes. Atul Gawande — cancer surgeon, public-health researcher, and best-selling author — has some simple ideas for treating a painfully complex system.