 The framework has also been generalized to variable-population choice problems, so as to formalize population ethics in the tradition of Parfit (1984). Here, we must rank-order social alternatives (e.g., possible worlds) in which different individuals exist. Let \(N(x)\) denote the set of individuals existing under alternative \(x\). For example, the set \(N(x)\) could differ from the set \(N(y)\), when \(x\) and \(y\) are distinct alternatives (this generalizes our previous assumption of a fixed set \(N)\). The variable-population case raises questions such as whether a world with a smaller number of better-off individuals is better than, equally good as, or worse than a world with a larger number of worse-off individuals. (The focus here is on axiological questions about the relative goodness of such worlds, not normative questions about the rightness or wrongness of bringing them about.)