How do we decide what is "good" and what is "bad"? According to the ethical theory of Utilitarianism, to do good is to "always perform that act, of those available, that will bring the most happiness or the least unhappiness." By far the most widely read introduction to this theory, John Stuart Mill"s Utilitarianism is one of the most important and controversial works of moral philosophy ever written. From common-day dilemmas to large-scale social decisions, this exposition remains as relevant today as it was to intellectual and moral dilemmas of the nineteenth century. Parallel text in English and Russian.