The Principle of
Maximum Utility is the idea that one
should attempt to
maximize total utility for all beings, or at least some
weighted average of all beings.
Usually people weigh themselves heavier, but
altruistic people would have
all humans weigh the same. Really
silly animal lovers would even allow animals a
nonzero weight.
Some think that the
quickest way to maximum utility is for everyone to be really
selfish, so we
evolve quicker.
When evaluating utility, you mustn't forget to include emotional states. So for example, killing one person to save two would save a life, but it would also create such a huge fear all throughout society that it wouldn't be worth it. If this
utilitarian government tried to do it secretly, to avoid scaring everyone, it would just make the consequences worse if they were discovered.