 What is crucial about this passage is Hempel’s emphasis on the pragmatic consideration of the time at which the argument is presented in relation to the time of occurrence of the explanandum event itself. Let us take this to be the observation that \(c\) is black and assume that occurs at a specific time \(t_1\). If the argument is presented prior to time \(t_1\) (before observing that \(c\) is black), then it is a prediction. If the argument is presented after time \(t_1\) (after observing that \(c\) is black), then it is a postdiction. Since explanations are usually advanced after the time of the occurrence of the event to be explained, they usually occur as postdictions. But there is nothing about their form that requires that.