Example population ethics: ordered discounted utility

This ar­ti­cle is a stub. Alas, you can’t help Wikipe­dia (or LessWrong) by ex­pand­ing it. Ex­cept through good com­ments.

Here I’ll pre­sent an old idea for a the­ory of pop­u­la­tion ethics. This post ex­ists mainly so that I can have some­thing to point to when I need this ex­am­ple.

Given a to­tal pop­u­la­tion , each with to­tal in­di­vi­d­ual util­ity over the whole of their lives, or­der them from low­est util­ity to the high­est so that im­plies . Th­ese util­ities are as­sumed to have a nat­u­ral zero point (the “life worth liv­ing” stan­dard, or similar).

Then pick some dis­count fac­tor , and define the to­tal util­ity of the world with pop­u­la­tion (which is the to­tal pop­u­la­tion of the world across all time) as

  • .

This is a pri­ori­tar­ian util­ity that gives greater weight to those least well off. It is not av­er­age util­i­tar­i­anism, and would ad­vo­cate cre­at­ing a hu­man with util­ity larger than than all other hu­mans (as long as it was pos­i­tive), and would ad­vo­cate against cre­at­ing a hu­man with nega­tive util­ity (for a util­ity in be­tween, it de­pends on the de­tails). In the limit , it’s to­tal util­i­tar­i­anism. In­creas­ing some­one’s in­di­vi­d­ual util­ity always im­proves the score. It (some­times) ac­cepts the “sadis­tic con­clu­sion”, but I’ve ar­gued that that con­clu­sion is mis­named (the con­clu­sion is a choice be­tween two nega­tive out­comes, mean­ing that call­ing it “sadis­tic” is a poor choice—the preferred out­come is not a good one, just a less bad one). Killing peo­ple won’t help, un­less they will have fu­ture life­time util­ity that is nega­tive (as ev­ery­one that ever lived is in­cluded in the sum). Note that this sets up a minor asym­me­try be­tween not-cre­at­ing peo­ple and kil­ling them.

Do I en­dorse this? No; I think a gen­uine pop­u­la­tion ethics will be more com­pli­cated, and needs a greater asym­me­try be­tween life and death. But it’s good enough for an ex­am­ple in many situ­a­tions that come up.