This chapter opens the question of aggregating wellbeing across time to determine the value of a single person’s life. It explains the imperfect analogy between this sort of aggregation and aggregation across time to determine the overall value of a world. It assesses the principle of temporal good, the analogue of the principle of personal good. It shows there are plausible grounds for doubting the principle, which derive from various putative pattern goods. Nevertheless, this chapter eventually adopts the principle of temporal good as a default position. From this default position, it derives a same-lifetime addition theorem, which says that wellbeing is aggregated within a life additively.
Keywords: principle of temporal good, pattern goods, aggregation across time, same-lifetime addition