“Nature has placed mankind under the governance of two sovereign masters, pain and pleasure.”
Bentham, An Introduction to the Principles of Morals and Legislation, ch. I
Utilitarianism
Bentham's opening move sounds almost administrative: pleasure and pain can be weighed, and the right act is whichever produces the largest net sum of good over harm, added across everyone it touches. A unit is a unit, whoever feels it. Mill kept the sum but rejected the idea that pleasures differ only in amount — some kinds of good, he argued, are worth more regardless of quantity, and people who've genuinely tried both will tell you so.
Self-driving cars turned this from theory into hardware. If a crash is unavoidable, should the software minimize total casualties, even if that means the car chooses its own passenger? Germany's ethics commission tried to rule the question out entirely, banning the weighing of victims against each other — then quietly left that exact question unresolved when the actual law was written. A utilitarian doesn't get to dodge it. Somebody has to add up the harm either way, the only choice is whether you do it on purpose or by default.
What Utilitarianism gets wrong
Rawls put the sharpest version of this: utilitarianism treats a whole society's welfare the way one person treats trade-offs across their own life, netting gains against losses as if it were all the same subject bearing both. It isn't. The pedestrian who dies so five others live isn't compensated by their survival, and no sum makes that trade fair to the one person paying for it. Stoics would add that outcomes were never yours to guarantee in the first place — the calculus asks you to answer for a total no one person actually controls.