 Trees usually grow a certain way. Each year, there is the passage of the four seasons with a tree growing more quickly at some times and more slowly at others. As a result, each year a tree adds a “ring” to its girth in such a way that one might say that each ring means a year of growth. If we find a tree stump that has twelve rings, then that means that the tree was twelve years old when it died. But, it is not an entirely inviolable law that a tree grows a ring each year. Such a law, if it is one, is at most a ceteris paribus law. It holds only given certain background conditions, such as that weather conditions are normal. If the weather conditions are especially bad one season, then perhaps the tree will not grow enough to produce a new ring. One might, therefore, propose that if conditions are normal, then n rings means that the tree was n years old when it died. This idea makes its first appearance when Stampe (1977) invokes it as part of his theory of “fidelity conditions.”