The opposite end of the spectrum causes problems too: "It's ok for some people to die, if it results in a small amount of good for a large number of people." On

The opposite end of the spectrum causes problems too: "It's ok for some people to die, if it results in a small amount of good for a large number of people." One way to look at the problem with that in practice is that small amounts of good and large numbers of people both tend to involve a lot of uncertainty. When we're allowed to do motivated reasoning with enough uncertainty, we can usually prove whatever we want, and that sort of simple utilitarianism ends up being too easy to abuse. I think we can look at cultural taboos as a practical solution to this problem: "Ok, clearly there's no reliable way for us to say what killing is good and what killing is bad, and we all agree that most of it is bad, so let's make the simplifying assumption that all killing is bad."