While I haven’t heard the term “asymmetry” before, it looks like this is a more general claim about population ethics. The “GiveWell view” implies asymmetry, but it also implies that extending a life is good in proportion to the (quality-adjusted?) length of life added, and that it’s irrelevant what other people you could affect (i.e., in my second thought experiment, B = C). As I discuss in OP, this has additional problems that merely assuming asymmetry does not. Most significantly, to fix certain problems with asymmetry, you probably have to assume B < C, but the GiveWell view assumes B = C.
While I haven’t heard the term “asymmetry” before, it looks like this is a more general claim about population ethics. The “GiveWell view” implies asymmetry, but it also implies that extending a life is good in proportion to the (quality-adjusted?) length of life added, and that it’s irrelevant what other people you could affect (i.e., in my second thought experiment, B = C). As I discuss in OP, this has additional problems that merely assuming asymmetry does not. Most significantly, to fix certain problems with asymmetry, you probably have to assume B < C, but the GiveWell view assumes B = C.
Thanks for making the distinction clear!