Why It Took So Long to Change

Lind proved lemon juice cured scurvy in 1747 and the Navy issued it in 1795 — forty-eight years, and a great many dead sailors in between. Semmelweis showed the deaths drop and was ignored for a lifetime. The seat belt waited twenty-five years for a law. None of this is because people were stupid, and working out what it actually was is the point: evidence without an explanation, a cost somebody has to bear, a system that has to exist first, and the fact that institutions forget.