Utilitarianism may well be the most influential secular ethical theory in the world today. It is also one of the most controversial. It clashes, or is widely thought to clash, with many conventional moral views, and with human rights when they are seen as inviolable. Would it, for example, be right to torture a suspected terrorist in order to prevent an attack that could kill and injure a large number of innocent people?

In this Very Short Introduction Katarzyna de Lazari-Radek and Peter Singer provide an authoritative account of the nature of utilitarianism, from its...