Utilitarianism offers an appealingly democratic framework for justice: the morally right action or policy is the one that maximizes overall welfare, with everyone's interests counted equally. It has been the foundation of much progressive reform — animal rights, criminal justice reform, foreign aid policy — and provides powerful tools for evaluating the consequences of institutional choices. Its difficulties are also well-known: the difficulty of measuring welfare across persons, the risk of sacrificing minorities for majority benefit, and the way it can, under certain conditions, justify outcomes that virtually every moral intuition condemns. Justice and the greatest good are not always the same thing.
Each step builds on the last.