Imprecision in the ethics of rescue

Suppose you can save one group of people or a larger group of different people, but you cannot save both groups. Are you morally required, ceteris paribus, to save the larger group? Some say, “No.” Far more say, without qualification, “Yes.” But some say, “It depends on the sizes of the groups.” In this paper, I argue that an attractive moral principle that seems on its face to support the second answer in fact supports a version of the third. In the process, I defend some revisionary claims about how the lives and deaths of different people compare evaluatively to one another. The most important of these for my purposes is the claim that the deaths of different people are on a par, other things being equal.