In population axiology, comparisons of the value of different outcomes have traditionally been done in highly idealized ways. This has been done, for example, by considering only net-levels of wellbeing and not their components; by assuming scenarios of perfect equality; and by taking for granted full certainty, instead of option uncertainty. As those idealized models of populations’ wellbeing are the only ones that have been considered to date, standard views in population axiology have been built upon them. As a result of this, they tend to reach conclusions that overlook risks of net-negative scenarios. Despite this, these views can nevertheless influence practical decision making, thus contributing to the creation of outcomes in which large numbers of human beings may have lives that are overall bad. Furthermore, it is more likely that this will happen in the case of nonhuman animals, both domesticated and living in the wild. The reason is that idealized population axiologies can be combined with flawed assumptions concerning animals’ wellbeing that are prevalent today. Avoiding such scenarios should be an important goal for longtermists.