Suppose that a nonmathematical, but philosophically minded, friend of yours claims that Laplace’s rule of succession must be incorrect because it can lead to ridiculous conclusions. “For instance,” says he, “the rule states that if a boy is 10 years old, having lived 10 years, the boy has probability 11/12 of living another year. On the other hand, if the boy has an 80-year-old grandfather, then, by Laplace’s rule, the grandfather has probability 81/82 of surviving another year. However, this is ridiculous. Clearly, the boy is more likely to survive an additional year than the grandfather is.” How would you answer your friend?