Bayes’s theorem, an 18th century formula, holds that with the right understanding of probabilities, most outcomes are predictable. But sometimes freak events occur. In the early hours of August 19th, a superyacht owned by the wife of Mike Lynch, a British tech entrepreneur who only months ago was cleared in a vast American fraud case, was struck and capsized by a waterspout, a form of tornado. On the morning of August 21st Mr Lynch was among six passengers missing. By that evening the rescue operation had found five bodies, and begun to bring them ashore. It looks like a tragic end to an extraordinary story.