 Arguably, even laws of succession do not always give rise to causal explanations. Such laws do not only allow for predictions, but also for retrodictions. That is, we can derive statements about events that are prior to events described by the antecedent conditions \(C_1,\) \(C_2,\) …, \(C_k\) in a DN explanation. Hempel (1965: 353) himself observed that Fermat’s principle may be used in a DN explanation of an event that precedes an event described by an antecedent condition.