That’s the problem with utilitarians. You abandon inviolable moral principles like the sanctity of life, you make the numbers big enough, and suddenly they’re eager to turn themselves into mass murderers. You don’t even have to give them a push. Ask them if they’d torture a child in order to increase the global development index by one percent and they will shout “YES” before you even get past “child.” They want to be self-consistent more than they want to be good.
