 With reference to Temkin, Parfit himself proposed a closer look at what he called the Wide Dual Person-Affecting Principle: “One of two outcomes would be in one way better if this outcome would together benefit people more, and in another way better if this outcome would benefit each person more.” Parfit 2017, 154. According to Parfit, “this Wide Principle would be only one of our beliefs.” Parfit 2017, 157. It is not, on its own, the “Theory X” Parfit urged us to seek decades ago. Parfit 1987, 378. But it, like other forms of pluralism (radical or not), faces an important challenge. Pluralistic theories have ample resources for generating what many philosophers will consider plausible accounts of (for example) both the nonidentity problem and the repugnant conclusion. The problem is going to be one of containment. The theories are too rich, and we don’t yet know by what principle the particular view can be stopped from generating what we consider to be implausible accounts of the problem cases as well. Indefinite and difficult to test, however, as such theories may be, they nonetheless offer an outline of an approach that may have more promise than the alternatives for ultimately providing a plausible analyses of the full range of population problems.