The ethical and political tradition holding that the rightness of an action or policy is determined by its consequences for overall wellbeing, and that no one's wellbeing counts for more than anyone else's. Its radicalism is easy to miss at this distance: in an age of rank and inherited privilege, insisting that each is to count for one and none for more than one was a levelling claim.
Bentham gave it systematic form in An Introduction to the Principles of Morals and Legislation (1789), proposing that pleasure and pain be measured and aggregated so that legislation could be assessed like any other technical problem. The framework licensed his lifelong campaign against legal cruelty and, unusually for his time, his arguments for animal welfare and against the criminalization of homosexuality. John Stuart Mill, raised inside the doctrine, revised it in Utilitarianism (1861) by distinguishing higher from lower pleasures — an attempt to answer the charge that the philosophy was fit for swine, and one many utilitarians think abandons the theory's own measure. Sidgwick then produced its most rigorous statement and, honestly, admitted he could not reconcile it with the rational claims of self-interest.
The tradition splits over what the principle governs. Act utilitarians assess each choice by its consequences; rule utilitarians assess practices and follow them even when a particular breach would pay, which critics say collapses either into act utilitarianism or into rule-worship. Preference and welfare variants replace happiness with the satisfaction of desires or with objective wellbeing, mostly to avoid the awkward implications of measuring mental states.
Its objections are as well known as its arguments. Rawls charged that utilitarianism does not take seriously the distinction between persons, since it permits imposing losses on some for larger gains to others; Bernard Williams argued it alienates agents from their own projects and integrity; the standard cases about punishing the innocent are hard to answer within the theory. Yet no framework has shaped modern public policy more thoroughly — cost-benefit analysis, welfare economics and health-resource allocation are utilitarian in structure whatever their practitioners believe.
